Abstract: Dengue viruses (DENV) cause countless human deaths each year, whilst West Nile virus (WNV) has re-emerged as an important human pathogen. There are currently no WNV or DENV vaccines licensed for human use, yet vaccines exist against other flaviviruses. To investigate flavivirus cross-reactivity, sera from a human cohort with a history of vaccination against tick-borne encephalitis virus (TBEV), Japanese encephalitis virus (JEV) and yellow fever virus (YFV) were tested for antibodies by plaque reduction neutralization test. Neutralization of louping ill virus (LIV) occurred, but no significant neutralization of Murray Valley encephalitis virus was observed. Sera from some individuals vaccinated against TBEV and JEV neutralized WNV, which was enhanced by YFV vaccination in some recipients. Similarly, some individuals neutralized DENV-2, but this was not significantly influenced by YFV vaccination. Antigenic cartography techniques were used to generate a geometric illustration of the neutralization titres of selected sera against WNV, TBEV, JEV, LIV, YFV and DENV-2. This demonstrated the individual variation in antibody responses. Most sera had detectable titres against LIV and some had titres against WNV and DENV-2. Generally, LIV titres were similar to titres against TBEV, confirming the close antigenic relationship between TBEV and LIV. JEV was also antigenically closer to TBEV than WNV, using these sera. The use of sera from individuals vaccinated against multiple pathogens is unique relative to previous applications of antigenic cartography techniques. It is evident from these data that notable differences exist between amino acid sequence identity and mapped antigenic relationships within the family Flaviviridae.

Abstract: The Israeli acute paralysis virus (IAPV) is a significant marker of honeybee colony collapse disorder (CCD). In the present work, we provide the first evidence that Varroa destructor is IAPV replication-competent and capable of vectoring IAPV in honeybees. The honeybees became infected with IAPV after exposure to Varroa mites that carried the virus. The copy number of IAPV in bees was positively correlated with the density of Varroa mites and time period of exposure to Varroa mites. Further, we showed that the mite-virus association could possibly reduce host immunity and therefore promote elevated levels of virus replication. This study defines an active role of Varroa mites in IAPV transmission and sheds light on the epidemiology of IAPV infection in honeybees.

Abstract: Plant viruses are biotrophic pathogens that need living tissue for their multiplication and thus, in the infection–defence equilibrium, they do not normally cause plant death. In some instances virus infection may have no apparent pathological effect or may even provide a selective advantage to the host, but in many cases it causes the symptomatic phenotypes of disease. These pathological phenotypes are the result of interference and/or competition for a substantial amount of host resources, which can disrupt host physiology to cause disease. This interference/competition affects a number of genes, which seems to be greater the more severe the symptoms that they cause. Induced or repressed genes belong to a broad range of cellular processes, such as hormonal regulation, cell cycle control and endogenous transport of macromolecules, among others. In addition, recent evidence indicates the existence of interplay between plant development and antiviral defence processes, and that interference among the common points of their signalling pathways can trigger pathological manifestations. This review provides an update on the latest advances in understanding how viruses affect substantial cellular processes, and how plant antiviral defences contribute to pathological phenotypes.

Abstract: While performing a nationwide survey of hepatitis E virus (HEV) infection among 450 wild boars (Sus scrofa leucomystax) that had been captured in Japan between November 2005 and March 2010, we found 16 boars (3.6%) with ongoing HEV infection: 11 had genotype 3 HEV, four had genotype 4 HEV and the remaining boar was infected with HEV of an unrecognized genotype (designated wbJOY_06). The entire wbJOY_06 genome was sequenced and was found to comprise 7246 nt excluding the poly(A) tail. The wbJOY_06 isolate was highly divergent from known genotype 1-4 HEV isolates derived from humans, swine, wild boars, deer, mongoose and rabbits (n=145) by 22.6-27.7%, rat HEV isolates (n=2) by 46.0-46.2%, and avian HEV isolates (n=5) by 52.5-53.1% over the entire genome. A Simplot analysis revealed no significant recombination between the existing HEV strains of genotypes 1-4. Therefore, we propose that the wbJOY_06 isolate is the first member of a previously unidentified genotype.

Abstract: The family Bunyaviridae of segmented, negative-stranded RNA viruses includes over 350 members that infect a bewildering variety of animals and plants. Many of these bunyaviruses are the causative agents of serious disease in their respective hosts, and are classified as emerging viruses because of their increased incidence in new populations and geographical locations throughout the world. Emerging bunyaviruses, such as Crimean–Congo hemorrhagic fever virus, tomato spotted wilt virus and Rift Valley fever virus, are currently attracting great interest due to migration of their arthropod vectors, a situation possibly linked to climate change. These and other examples of continued emergence suggest that bunyaviruses will probably continue to pose a sustained global threat to agricultural productivity, animal welfare and human health. The threat of emergence is particularly acute in light of the lack of effective preventative or therapeutic treatments for any of these viruses, making their study an important priority. This review presents recent advances in the understanding of the bunyavirus life cycle, including aspects of their molecular, cellular and structural biology. Whilst special emphasis is placed upon the emerging bunyaviruses, we also describe the extensive body of work involving model bunyaviruses, which have been the subject of major contributions to our overall understanding of this important group of viruses.

Abstract: A small subset of human immunodeficiency virus type 1 (HIV-1)-infected, therapy-naive individuals – referred to as long-term non-progressors (LTNPs) – maintain a favourable course of infection, often being asymptomatic for many years with high CD4+ and CD8+ T-cell counts (>500 cells μl−1) and low plasma HIV-RNA levels (<10 000 copies ml−1). Research in the field has undergone considerable development in recent years and LTNPs offer a piece of the puzzle in understanding the ways that persons can naturally control HIV-1 infection. Their method of control is based on viral, genetic and immunological components. With respect to virological features, genomic sequencing has shown that some LTNPs are infected with attenuated strains of HIV-1 and harbour mutant nef, vpr, vif or rev genes that contain single nuclear polymorphisms, or less frequently, large deletions, in conserved domains. Studies have also shown that some LTNPs have unique genetic advantages, including heterozygosity for the CCR5-Δ32 polymorphism, and have been found with excitatory mutations that upregulate the production of the chemokines that competitively inhibit HIV-1 binding to CCR5 or CXCR4. Lastly, immunological factors are crucial for providing LTNPs with a natural form of control, the most important being robust HIV-specific CD4+ and CD8+ T-cell responses that correlate with lower viral loads. Many LTNPs carry the HLA class I B57 allele that enhances presentation of antigenic peptides on the surface of infected CD4+ cells to cytotoxic CD8+ T cells. For these reasons, LTNPs serve as an ideal model for HIV-1 vaccine development due to their natural control of HIV-1 infection.

Abstract: Recent reports on a steady decline of honeybee colonies in several parts of the world caused great concern. There is a consensus that pathogens are among the key players in this alarming demise of the most important commercial pollinator. One of the pathogens heavily implicated in colony losses is deformed wing virus (DWV). Overt DWV infections manifested as deformed-wing syndrome started to become a threat to honeybees only in the wake of the ectoparasitic mite Varroa destructor, which horizontally transmits DWV. However, a direct causal link between the virus and the symptom ‘wing deformity’ has not been established yet. To evaluate the impact of different horizontal transmission routes, and especially the role of the mite in the development of overt DWV infections, we performed laboratory infection assays with pupae and adult bees. We could demonstrate that pupae injected with DWV dose-dependently developed overt infections characterized by deformed wings in adult bees, suggesting that DWV, if transmitted to pupae by the mite, is the causative agent of the deformed-wing syndrome. The OID50 (overt infection dosage) was approximately 2500 genome equivalents. Injecting more than 1×107 DWV genome equivalents into adult bees also resulted in overt infections while the same viral dosage fed to adult bees only resulted in covert infections. Therefore, both infection of adult bees through DWV-transmitting phoretic mites and infection of nurse bees through their cannibalizing DWV-infected pupae might represent possible horizontal transmission routes of DWV.

Abstract: We have previously demonstrated that the release of hepatitis E virus (HEV) from infected cells depended on ORF3 protein, which harbours one or two PSAP motifs To elucidate the PSAP motif(s) in the ORF3 protein during virion egress, five PSAP mutants derived from an infectious genotype 3 cDNA clone of pJE03-1760F/wt that can grow efficiently in PLC/PRF/5 cells were analysed Four mutants, including mutLSAP, mutPSAL, mutLSAL (the substituted amino acids in the authentic PSAP motif are underlined) and mutPLAP/PSAP (the changed amino acid in the additional PSAP motif is underlined) generated progenies as efficiently as the wild-type virus Conversely, the HEV RNA level in the culture supernatant of mutPLAP/LSAL RNA-transfected cells was significantly lower than in cells transfected with the wild-type RNA, similar to an ORF3-null mutant Consistent with the ORF3-deficient mutant, the mutPLAP/LSAL mutant with no intact PSAP motifs banded at 126–127 g ml−1 in sucrose, and was captured by anti-ORF2, but not by anti-ORF3, with or without prior treatment with detergent (01 % sodium deoxycholate) The absence of the ORF3 protein on the mutant particles in the culture supernatant was confirmed by Western blotting, despite the expression of ORF3 protein in the RNA-transfected cells, as detected by immunofluorescence and Western blotting Therefore, at least one of the two intact PSAP motifs in the ORF3 protein is required for the formation of membrane-associated HEV particles possessing ORF3 proteins on their surface, thus suggesting that the PSAP motif plays a role as a functional domain for HEV budding

Abstract: Newcastle disease virus (NDV) is an avian paramyxovirus that causes significant economic losses to the poultry industry worldwide. There is limited knowledge about the avian immune response to infection with virulent NDVs, and how this response may contribute to disease. In this study, pathogenesis and the transcriptional host response of chickens to a virulent NDV strain that rapidly causes 100% mortality was characterized. Using microarrays, a strong transcriptional host response was observed in spleens at early times after infection with the induction of groups of genes involved in innate antiviral and pro-inflammatory responses. There were multiple genes induced at 48 h post-infection including: type I and II interferons (IFNs), several cytokines and chemokines, IFN effectors and inducible nitric oxide synthase (iNOS). The increased transcription of nitric oxide synthase was confirmed by immunohistochemistry for iNOS in spleens and measured levels of nitric oxide in serum. In vitro experiments showed strong induction of the key host response genes, alpha IFN, beta interferon, and interleukin 1β and interleukin 6, in splenic leukocytes at 6 h post-infection in comparison to a non-virulent NDV. The robust host response to virulent NDV, in conjunction with severe pathological damage observed, is somewhat surprising considering that all NDV encode a gene, V, which functions as a suppressor of class I IFNs. Taken together, these results suggest that the host response itself may contribute to the pathogenesis of this highly virulent strain in chickens.

Abstract: Porcine reproductive and respiratory syndrome (PRRS) has a major negative economic impact on the swine industry worldwide. During the investigation of PRRS virus (PRRSV) in mainland China, European genotype (EU, type 1) PRRSV isolates were detected in swine herds both with and without clinical symptoms. Two complete genome sequences for Chinese type 1 PRRSV isolates were identified from viruses isolated from lung tissue and sera. The two viruses, designated BJEU06-1 and NMEU09-1, produced cytopathic effects in primary porcine alveolar macrophages but not in Marc-145 cells, and had a mean diameter of 55enm, as measured by transmission electron microscopy . Comparative sequence analysis revealed that they shared 87.0-91.5% and 58.0-58.2% identity with the EU and North American genotype (NA, type 2) prototypic strains LV and VR-2332, respectively. Remarkably, these isolates, characterized by concomitant deletions within non-structural protein 2 (Nsp2) and ORF3 hypervariable regions, have never been described. Phylogenetic trees showed that all of the novel Chinese isolates of European genotype are in the pan-European subtype 1 that is predominant in Europe. However, they evolved from different ancestors. These novel viruses are predicted to be products of the divergent evolution of ancestor PRRSV isolates introduced from Europe. This is the first report of type 1 PRRSV wild isolates being in mainland China. Our findings confirm that the Chinese type 1 PRRSV isolates originated from diverse progenitors and the type 1 and type 2 PRRSV isolates, having different biological properties, have coexisted on the Chinese mainland for several years.

Abstract: Rose rosette was first described in the early 1940s and it has emerged as one of the most devastating diseases of roses. Although it has been 70 years since the disease description, the rosette agent is yet to be characterized. In this communication, we identify and characterize the putative causal agent of the disease, a negative-sense RNA virus and new member of the genus Emaravirus. The virus was detected in 84/84 rose rosette-affected plants collected from the eastern half of the USA, but not in any of 30 symptomless plants tested. The strong correlation between virus and disease is a good indication that the virus, provisionally named Rose rosette virus, is the causal agent of the disease. Diversity studies using two virus proteins, p3 and p4, demonstrated that the virus has low diversity between isolates as they share nucleotide identities ranging from 97 to 99%.

Abstract: Circoviruses consist of highly prevalent and genetically diverse porcine and avian pathogens. The genomes of cycloviruses, a proposed new genus in the family Circoviridae, were recently identified in human and chimpanzee faeces. Here, six cyclovirus and four circovirus genomes from the tissues of chickens, goats, cows, and a bat were amplified and sequenced using rolling-circle amplification and inverse PCR. A goat cyclovirus was nearly identical to a cyclovirus from a cow. USA beef contained circoviruses with >99 % similarity to porcine circovirus 2b. Circoviruses in chicken were related to those of pigeons. The close genetic similarity of a subset of cycloviruses and circoviruses replicating in distinct animal species may reflect recent cross-species transmissions. Further studies will be required to determine the impact of these highly prevalent infections on the health of farm animals.

Abstract: The family Endornaviridae contains several members from diverse hosts, including plants, fungi and oomycetes. They are found as large dsRNA elements with a nick in the coding strand. All members encode a conserved RNA-dependent RNA polymerase, but no other domain that is conserved among all members. Based on the conserved domain database comparison the various domains have different origins, indicating a highly modular evolutionary history. In some cases, domains with similar putative functions are found that are derived from different protein families, indicating convergent evolution for a required function.

Abstract: Bell peppers (Capsicum annuum) harbour a large dsRNA virus The linear genome (147 kbp) of two isolates from Japanese and USA bell pepper cultivars were completely sequenced and compared They shared extensive sequence identity and contained a single, long ORF encoding a 4815 aa protein This polyprotein contained conserved motifs of putative viral methyltransferase (MTR), helicase 1 (Hel-1), UDP-glycosyltransferase and RNA-dependent RNA polymerase This unique arrangement of conserved domains has not been reported in any of the known endornaviruses Hence this virus, for which the name Bell pepper endornavirus (BPEV) is proposed, is a distinct species in the genus Endornavirus (family Endornaviridae) The BPEV-encoded polyprotein contains a cysteine-rich region between the MTR and Hel-1 domains, with conserved CXCC motifs shared among several endornaviruses, suggesting an additional functional domain In agreement with general endornavirus features, BPEV contains a nick in the positive-strand RNA molecule The virus was detected in all bell pepper cultivars tested and transmitted through seed but not by graft inoculations Analysis of dsRNA patterns and RT-PCR using degenerate primers revealed putative variants of BPEV, or closely related species, infecting other C annuum genotypes and three other Capsicum species (C baccatum, C chinense and C frutescens)

Abstract: We have previously demonstrated that an intact PSAP motif in the ORF3 protein is required for the formation and release of membrane-associated hepatitis E virus (HEV) particles with ORF3 proteins on their surface. In this study, we investigated the direct interaction between the ORF3 protein and tumour susceptibility gene 101 (Tsg101), a cellular factor involved in the budding of viruses containing the P(T/S)AP late-domain, in PLC/PRF/5 cells expressing the wild-type or PSAP-mutated ORF3 protein and Tsg101 by co-immunoprecipitation. Tsg101 bound to wild-type ORF3 protein, but not to the PSAP-inactive ORF3 protein. To examine whether HEV utilizes the multivesicular body (MVB) pathway to release the virus particles, we analysed the efficiency of virion release from cells upon introduction of small interfering RNA (siRNA) against Tsg101 or dominant-negative (DN) mutants of Vps4 (Vps4A and Vps4B). The relative levels of virus particles released from cells depleted of Tsg101 decreased to 6.4 % of those transfected with negative control siRNA. Similarly, virion egress was significantly reduced by the overexpression of DN forms (Vps4AEQ or Vps4BEQ). The relative levels of virus particles released from cells expressing Vps4AEQ and Vps4BEQ were 19.2 and 15.6 %, respectively, while the overexpression of wild-type Vps4A and Vps4B did not alter the levels of virus release. These results indicate that the ORF3 protein interacts with Tsg101 through the PSAP motifs in infected cells, and that Tsg101 and the enzymic activities of Vps4A and Vps4B are involved in HEV release, thus suggesting that HEV requires the MVB pathway for egress of virus particles.

Abstract: To investigate whether currently circulating H9N2 avian influenza viruses (AIVs) in domestic poultry have evolved in Korean poultry since 2007, genetic and serological comparisons were conducted of H9N2 isolates from poultry slaughterhouses from January 2008 to December 2009. The isolation rate was relatively low in 2008 but increased gradually from January 2009 onwards. Genetic and phylogenetic analyses revealed that reassortant viruses had emerged, generating at least five novel genotypes, mostly containing segments of a previously prevalent domestic H9N2 virus lineage (Ck/Korea/04116/04-like). It was noteworthy that the N2 genes of some H9N2 isolates (genotypes D, E and F) were derived from those of H3N2-like viruses commonly isolated among domestic ducks in live-poultry markets. Animal challenge studies demonstrated that the pathogenicity of Ck/Korea/SH0906/09 (genotype B) and Ck/Korea/SH0912/09 (genotype F) in domestic avian species was altered due to reassortment. Furthermore, serological analysis revealed that the isolates were antigenically distinct from previous Korean H9N2 viruses including Ck/Korea/01310/01. Such antigenic diversity was illustrated further in experiments using H9N2-immunized chickens, which could not inhibit the replication and transmission of challenge viruses from each genotype. These results suggest that H9N2 viruses from domestic poultry have undergone substantial evolution since 2007 by immune selection as a result of vaccinal and natural immunity, coupled with reassortment. Taken together, this study demonstrates that periodical updating of vaccine strains, based on continuous surveillance data, is an important issue in order to provide sufficient protectivity against AIV infections.

Abstract: A natural reassortant influenza A virus consisting of seven genome segments from pandemic (H1N1) 2009 virus and a neuraminidase segment from a Eurasian porcine H1N1 influenza A virus was detected in a pig herd in Germany. The obvious reassortment compatibility between the pandemic (H1N1) 2009 and H1N1 viruses of porcine origin raises concern as to whether swine may become a reservoir for further reassortants of pandemic (H1N1) 2009 viruses with unknown implications for human health and swine production.

Abstract: Infectious salmon anemia virus (ISAV) is an orthomyxovirus responsible for a significant disease of farmed Atlantic salmon. Fallowing and re-establishment of the Atlantic salmon farming industry in the Faroes following a recent devastating infectious salmon anaemia (ISA) disease epidemic provided a unique opportunity to study the risk of re-emergence of disease. Over 53 months, 2787 of 34 573 (8.1 %) apparently healthy Atlantic salmon analysed tested positive for ISAV by RT-PCR. Sequence analysis revealed the putative low-pathogenic ISAV-HPR0 subtype in all cases. Results demonstrated that ISAV-HPR0 appeared as a seasonal and transient infection without detectable ISA mortality or pathology. This finding, coupled to an apparent gill tropism of ISAV-HPR0, suggests ISAV-HPR0 causes a subclinical respiratory infection more like seasonal influenza, as opposed to the systemic infection and serious disease caused by highly pathogenic ISAV. The mean time before marine sites became infected was 7.7 months after transfer to seawater of the fish, suggesting a potentially unknown marine reservoir of infection. Sequence analysis identified two main subtypes of ISAV-HPR0 sequences, one of which showed close genetic association with ISAV isolates responsible for the disease outbreak in the Faroes. Thus ISAV-HPR0 might represent an ancestor of pathogenic variants and thus be a potential risk factor in the emergence of new strains of disease-causing ISAV. Our data, however, suggest that the risk of emergence of pathogenic ISAV variants from a reservoir of ISAV-HPR0 is low. This risk is probably being further reduced by practical management strategies adopted in the Faroes and aimed at reducing the potential for maintenance and adaptation of ISAV-HPR0.

Abstract: Psittacine beak and feather disease (PBFD) has a broad host range and is widespread in wild and captive psittacine populations in Asia, Africa, the Americas, Europe and Australasia. Beak and feather disease circovirus (BFDV) is the causative agent. BFDV has an ∼2 kb single stranded circular DNA genome encoding just two proteins (Rep and CP). In this study we provide support for demarcation of BFDV strains by phylogenetic analysis of 65 complete genomes from databases and 22 new BFDV sequences isolated from infected psittacines in South Africa. We propose 94% genome-wide sequence identity as a strain demarcation threshold, with isolates sharing >94% identity belonging to the same strain, and strain subtypes sharing >98% identity. Currently, BFDV diversity falls within 14 strains, with five highly divergent isolates from budgerigars probably representing a new species of circovirus with three strains (budgerigar circovirus; BCV-A, -B and -C). The geographical distribution of BFDV and BCV strains is strongly linked to the international trade in exotic birds; strains with more than one host are generally located in the same geographical area. Lastly, we examined BFDV and BCV sequences for evidence of recombination, and determined that recombination had occurred in most BFDV and BCV strains. We established that there were two globally significant recombination hotspots in the viral genome: the first is along the entire intergenic region and the second is in the C-terminal portion of the CP ORF. The implications of our results for the taxonomy and classification of circoviruses are discussed.

Abstract: Tomato spotted wilt virus (TSWV; genus Tospovirus, family Bunyaviridae) genetic diversity was evaluated by sequencing parts of the three RNA genome segments of 224 isolates, mostly from pepper and tomato crops in southern Europe. Eighty-three per cent of the isolates showed consistent clustering into three clades, corresponding to their geographical origin, Spain, France or the USA, for the three RNA segments. In contrast, the remaining 17% of isolates did not belong to the same clade for the three RNA segments and were shown to be reassortants. Among them, eight different reassortment patterns were observed. Further phylogenetic analyses provided insights into the dynamic processes of the worldwide resurgence of TSWV that, since the 1980s, has followed the worldwide dispersal of the western flower thrips (Frankliniella occidentalis) tospovirus vector. For two clades composed essentially of Old World (OW) isolates, tree topology suggested a local re-emergence of indigenous TSWV populations following F. occidentalis introductions, while it could not be excluded that the ancestors of two other OW clades were introduced from North America contemporarily with F. occidentalis. Finally, estimation of the selection intensity that has affected the evolution of the NSs and nucleocapsid proteins encoded by RNA S of TSWV suggests that the former could be involved in the breakdown of resistance conferred by the Tsw gene in pepper.

Abstract: Circoviruses are present worldwide in birds and pigs but their occurrence in fish has not yet been reported. Recently, increased mortality was observed in barbel fry (Barbus barbus) in Hungary. This paper reports the detection of previously unknown circular viral DNA genomes in barbels by the use of a circovirus-specific wide-range nested PCR. The analysis of two complete genomes (Barbel circovirus, BaCV1 and BaCV2) indicated that they belonged into a new genetic group within the family Circoviridae, distinct from known circoviruses and circovirus-like genomes. Their genome size was 1957 bases and contained two major ORFs similar to the capsid and replication-associated protein genes of circoviruses. A connection between the presence of the virus and clinical manifestations of the infection could not be proved.

Abstract: Expansion of the CD8 T-cell memory pool, also known as 'memory inflation', for certain but not all viral epitopes in latently infected host tissues is a special feature of the immune response to cytomegalovirus. The L(d)-presented murine cytomegalovirus (mCMV) immediate-early (IE) 1 peptide is the prototype of an epitope that is associated with memory inflation. Based on the detection of IE1 transcripts in latently infected lungs it was previously proposed that episodes of viral gene expression and antigenic activity due to desilencing of a limited number of viral genes may drive epitope-specific memory inflation. This would imply direct antigen presentation through latently infected host tissue cells rather than cell death-associated cross-presentation of viral antigens derived from productively infected cells through uninfected, professional antigen-presenting cells (profAPCs). To address the role of bone marrow-derived profAPCs in CD8 T-cell priming and memory to mCMV, we have used here a combined sex-mismatched and MHC class-I mismatched dual-marker bone marrow chimera model in which presentation of the IE1 epitope is restricted to donor-derived sry(+)L(d+) cells of haematopoietic differentiation lineages. Successful CD8 T-cell priming specific for the L(d)- and D(d)-presented inflationary epitopes IE1 and m164, respectively, but selective failure in IE1 epitope-specific memory inflation in these chimeras indicates different modes of antigen presentation involved in CD8 T-cell priming and memory inflation. These data suggest that memory inflation during mCMV latency requires expression of the epitope-presenting MHC class-I molecule by latently infected non-haematopoietic host tissue cells and thus predicts a role for direct antigen presentation in memory inflation.

Abstract: Hepatitis E virus (HEV) ORF1 protein (pORF1) contains methyltransferase (MetT), papain-like cysteine protease (PCP), RNA helicase (Hel) and RNA-dependent RNA polymerase (RdRp) domains. ORF1 sequence analysis showed two consensus LXGG cleavage sites at 664 and 1205. LXGG sequence is recognized by viral and cellular deubiquitinating enzymes. The protein encompassing the predicted MetT-PCP domains of HEV ORF1 was tested for deubiquitinating activity using fluorogenic substrates - ubiquitin-7-amino-4-methylcoumarin (AMC), IFN-stimulated gene 15 (ISG15)-AMC, Nedd8-AMC and SUMO-AMC. MetT-PCP cleaved all four substrates but processing of ISG15-AMC was more robust. There was no processing of the Hel and RdRp domains having the conserved (1205) LXGG site by the protein. MetT-PCP carried out deISGylation of the ISG15-conjugated cellular proteins, suggesting a possible role in combating cellular antiviral pathways.

Abstract: The role of the ancestral sylvatic cycle of the African swine fever virus (ASFV) is not well understood in the endemic areas of eastern Africa. We therefore analysed the ASF infection status on samples collected from 51 free-ranging warthogs (Phacocherus africanus) and 1576 Ornithodorus porcinus ticks from 26 independent warthog burrows at a single ranch in Kenya. Abattoir samples from 83 domestic pigs without clinical symptoms, originating from specific locations with no recent reported ASF outbreaks were included in this study. All samples were derived from areas of central Kenya, where ASF outbreaks have been reported in the past. Infection with ASFV was confirmed in 22 % of O. porcinus pools, 3.22 % of adult warthog serum samples and 49 % of domestic pig serum samples by using p72-based PCR. All of the warthog sera were positive for anti-ASFV antibodies, investigated by using ELISA, but none of the domestic pig sera were positive. Twenty O. porcinus-, 12 domestic pig- and three warthog-derived viruses were genotyped at four polymorphic loci. The ASFV isolates from ticks and domestic pigs clustered within p72 genotype X. By contrast, ASF viruses genotyped directly from warthog sera, at same locality as the tick isolates, were within p72 genotype IX and genetically similar to viruses causing recent ASF outbreaks in Kenya and Uganda. This represents the first report of the co-existence of different ASFV genotypes in warthog burrow-associated ticks and adult wild warthogs. The data from this and earlier studies suggest transfer of viruses of at least two different p72 genotypes, from wild to domestic pigs in East Africa.

Abstract: Human respiratory syncytial virus (RSV), a leading cause of respiratory tract infections in infants, inhibits type I interferon (IFN)-dependent signalling, as well as IFN synthesis. RSV non-structural protein NS1 plays a significant role in this inhibition; however, the mechanism(s) responsible is not fully known. The transcription factor interferon regulatory factor (IRF)-3 is essential for viral-induced IFN-β synthesis. In this study, we found that NS1 protein inhibits IRF-3-dependent gene transcription in constitutively active IRF-3 overexpressing cells, demonstrating that NS1 directly targets IRF-3. Our data also demonstrate that NS1 associates with IRF-3 and its transcriptional coactivator CBP, leading to disrupted association of IRF-3 to CBP and subsequent reduced binding of IRF-3 to the IFN-β promoter without blocking viral-induced IRF-3 phosphorylation, nuclear translocation and dimerization, thereby identifying a novel molecular mechanism by which RSV inhibits IFN-β synthesis.

Abstract: Spherical nanoparticles (SNPs) were generated by two-step thermal remodelling of native tobacco mosaic virus (TMV) at 94 °C Particles of irregular shape and varying size were generated by TMV at 90 °C They could be converted into SNPs by heating at 94 °C and were considered to be intermediate precursors of SNPs In addition to SNP monomers (53 nm diameter), generated by individual TMV virions, large SNPs (100-800 nm diameter) were assembled The size of the SNPs depended on the TMV concentration The SNPs could be generated by distinct forms of RNA-free TMV coat protein (CP) aggregates and individual CP subunits A one-step SNP assembly appeared to occur in these cases These results show that SNPs represent a new type of particle nanoplatform for producing compositions of SNPs with foreign protein molecules bound to their surface

Abstract: Dengue virus (DENV) causes a wide range of illnesses in humans: dengue fever (DF), dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS). Animal models that constantly develop high levels of viraemia are required for the development of protective and preventive measures. Common marmosets (Callithrix jacchus) demonstrated high levels of viraemia after inoculation with clinical isolates of four serotypes of DENV; in particular, over 106 genome copies ml−1 after inoculation with DENV-2. Non-structural protein 1 and DENV-specific IgM and IgG antibodies were consistently detected. The DENV-2 genome was detected in lymphoid organs including the lymph nodes, spleen and thymus, and also in non-lymphoid organs. DENV antigen was detected by immunohistochemistry in the liver and spleen from inoculated marmosets. Four marmosets were reinoculated with DENV-2 at 33 weeks after primary inoculation with DENV-2. The DENV-2 genome was not detected in any of these marmosets, indicating protection from a secondary infection. The results indicate that common marmosets are highly sensitive to DENV infection, and suggest that marmosets could be a reliable primate model for the evaluation of candidate vaccines.

Abstract: Stress-activated protein kinases (SAPKs), including p38 mitogen-activated protein kinase (p38 MAPK) and c-Jun N-terminal kinase (JNK), are usually activated in response to different environmental stimuli, including virus infection. In the present study, the roles of SAPKs during Singapore grouper iridovirus (SGIV) infection were investigated in fish cells. The results showed that increased phosphorylation of JNK1/2 and p38 MAPK occurred during active replication of SGIV in grouper cell cultures. Moreover, downstream effectors (c-Jun, MAPK-activated protein kinase 2, p53, activator protein 1, Myc and nuclear factor of activated T cells) were activated after SGIV infection, suggesting that SGIV replication activated the JNK and p38 MAPK signalling pathways. Notably, using specific inhibitors, it was found that viral gene transcripts, protein expression and viral titres were not affected by inhibition of p38 MAPK but were suppressed significantly by inhibiting JNK1/2 activation. In addition, transcription of grouper immune genes including interferon regulatory factor 1, interleukin-8 and tumour necrosis factor alpha (TNF-α) were regulated by JNK, whilst only TNF-α was regulated by p38 MAPK. It is proposed that the JNK pathway is important for SGIV replication and modulates the inflammatory responses during virus infection.

Abstract: To investigate viral pathogens potentially involved in a mortality event of 21 Pacific harbor seals (Phoca vitulina richardsii) in California in 2000, viral metagenomics was performed directly on lung samples from five individuals. Metagenomics revealed a novel seal anellovirus (SealAV), which clusters phylogenetically with anelloviruses from California sea lions and domestic cats. Using specific PCR, SealAV was identified in lung tissue from two of five animals involved in the 2000 mortality event, as well as one of 20 harbor seal samples examined post-mortem in 2008. The identification of SealAV in multiple years demonstrates that this virus is persistent in the harbor seal population. SealAV is the second anellovirus reported in the lungs of pinnipeds, suggesting that anellovirus infections may be common amongst marine mammals and that more research is needed to understand the roles of these viruses in marine mammal health and disease.