Abstract: Previous serological studies strongly suggested Akabane virus to be the etiologic agent of epizootic abortion and congenital arthrogryposis-hydranencephaly in cattle, and this view was further corroborated in this study by the isolation of the virus from an aborted fetus in an epizootic of the disease and from a fetus extracted from a cow which was suggested by serologic tests to have a recent infection with the virus. The latter fetus had histological changes of encephalomyelitis and polymyositis, and specific antigens of Akabane virus was shown by the immunofluorescent technique in brain tissues as well as skeletal muscular tissues. The virus was recovered from various fetal tissues and fluids, and in relatively large amounts from brain, spinal cord, cerebral fluid, skeletal muscles and fetal placenta. The intracranial inoculation of suckling mice, 1–2 days of age, was the most sensitive system for Akabane virus isolation and Hm Lu-1, a continuous cell line from hamster lung, seemed almost as sensitive as suckling mice.

Abstract: Differences in the pathogenesis of porcine parvovirus (PPV) were shown when pregnant gilts were infected by the oral and intramuscular (i.m.) routes.

Abstract: MHV3 has three distinct effects in different strains of mice: strain A mice are completely resistant, most strains (including C57BL, DBA/2, BALB/c and NZB strains) die of acute hepatitis whereas in certain strains (eg. C3H and A2G) the virus produces a persistent infection with neurological symptoms. In cultures of peritoneal macrophages from susceptible strains, MHV-3 replicated freely, with giant cell formation. No replication was observed in macrophages from strain A mice. In contrast to this full susceptibility or resistance, macrophage cultures from strains of mice in which persistent infections occur showed an intermediate susceptibility, as judged by the intensity of the cytopathic effect, the presence of viral antigens in the cytoplasm and levels of viral replication. Possible ways in which the intermediate susceptibility of macrophages and persistent infections might be related are discussed.

Abstract: The inter-epidemic phase of feline calicivirus was studied in a number of cats. During this period animals asymptomatically shed infective virus which was monitored at a number of sites and during different environmental conditions. Analysis of the amounts of virus shed by different cats showed that excretion occurred almost exclusively from the oropharynx, fluctuated with time, but was not influenced by periods of natural or artificial stress. Viral excretion from one individual cat was fairly constant although it appears that cats might be divided into high, medium or low level excretors. This variation in levels of excretion appears to have epidemiological importance in that high-level excretors more easily infect susceptible individuals.

Abstract: In human diploid fibroblast LEP cells infected with AD169 strain of human cytomegalovirus (CMV) a sharp increase of cytosol thymidine kinase activity was observed. The properties of the cytosol enzymes from infected and non-infected cells were compared. No significant differences between the enzymes from infected and control cells were observed in substrate specificity, pH dependence, thermostability and relative electrophoretic mobility. Human sera containing high titres of CMV complement-fixing antibodies did not neutralize the enzyme from infected cells. It is concluded from these results that the increase of cytosol thymidinekinase activity in CMV-infected cells was due to an enhancement of cellular thymidine kinase.

Abstract: A stabilized modification of the single radial haemolysis-in-gel (HIG) technique was developed. Crude mumps or influenza virus preparations were coupled to erythrocytes with CrCl3 and mounted in agarose gel containing diluted guinea pig serum.

Abstract: Diarrhea developed in five newborn rhesus monkeys(Macaca mulatta) inoculated orally on the first day of life with the human reovirus-like agent of infantile gastroenteritis. Incubation period ranged from 2–5 days; virus particles were detected in stools in association with illness, and virus shedding lasted between 1 and 3 days. Virus derived from monkeys that developed illness following inoculation was infectious for other monkeys but did not induce diarrhea which could be associated temporally with virus shedding. Viral antigens were also detected in tissues of the grossly abnormal small intestine of an acutely-ill monkey. Serum antibody responses were demonstrated in two of the ill animals by complement-fixation and/or immunofluorescence.

Abstract: Herpes simplex virus (t{SV) types 1 and 2 are among the most prevalent infectious agents in man, producing a wide variety of clinical manifestations. The infection may iItvolve the mouth, eyes, skin, urogenital tract, or brain. The disease is particularly severe in newborns and in immunosuppressed patients, and the virus has been incriminated as a possible causative agent of cancer. The recurrent form of herpes is associated with pronounced physical discomfort and serious psychological problems. I t has been estimated that up to a third of the world population has recurrent episodes due to HSV and that over one hall of these patients have more than one attack each year. In the United States there might be up to 500,000 cases of primary or recurrent ocular herpes and up to 5000 cases of herpes encephalitis each year. The second most common venereal disease after gonorrhoea is genital herpes, caused primarily by the type 2 virus, with at least 100,000 cases each year. Genital infection during pregnancy may cause abortion or severe disease of the newborn infant and at least 100 cases of neonatal disseminated herpes infections occur in the U.S.A. each year (95). Although not a life-threatening condition, recurrent oral, ocular and genital herpes is, by the large number of patients involved, one of the most important sociomedical problems of our times. l~etatively few aspects of recurrent herpes infection are well understood and many aspects are still subject to various interpretations. In the following presentation, the main points discussed will be: the site of the latent infection, the state of the latent virus, the factors involved in the initiation of recurrent eruptions and the maintenance of latency, and the difficulties of treatment of recurrent, herpes.

Abstract: The appearence of cell-mediated immunity was studied in Aujeszky diseased pigs with the aid of thein vitro stimulation of sensitized lymphocytes. The first cell-mediated immunity reaction of lymphocytes occurred 4 days after infection. From day 7 to 35, the latest day tested, the reactions were most marked with lymphocytes from lymph nodes and spleen, whereas blood and thymus lymphocytes reacted less frequently; bone marrow lymphocytes showed no response. Reinfection did not considerably enhance lymphocyte reactivity. Humoral immunity was demonstrated a few days later than cell-mediated immunity. Neutralizing antibodies were first detected at day 7, reaching optimal titers at day 14. Complement fixing antibodies were detected from day 14 onward. Reinfection caused a very weak booster effect only on neutralizing antibody production. The sensitivity of the neutralization test could be enhanced up to sixfold by the addition of fresh guinea pig complement.

Abstract: Virazole (ribavirin) inhibits the RNA synthesis of an influenza A virus (fowl plague). Neither virion RNA nor complementary RNA are produced. Although the effect of virazole can be counteracted by guanosine the inhibitor does not interfere with the uptake or incorporation of labelled guanosine into chick embryo cells, nor does replacement of glucose by mannose amplify the effect of virazole. Thus virazole seems not to act via an interference with the GTP pool. Synthesis of Semliki Forest virus RNA is not affected by virazole.

Abstract: Antibody and cell-mediated immune responses were measured in rabbits immunized with live, UV inactivated herpes simplex virus or with a subunit vaccine containing envelope proteins. All the types of immunization procedures induced the production of antibody as well as a specific cellular immunity. Furthermore, the subunit vaccine was as effective as the immunization with live or UV inactivated virus to prevent death upon challenge with live HSV. Live HSV induced a transient unresponsiveness of both B and T cells toin vitro stimulation with various mitogens.

Abstract: Primary chick kidney cells were infected with avian infectious bronchitis virus (IBV) and examined by electron microscopy. Virus particles entered the cells by viropexis and distinction could be made between engulfment by cell processes (phagocytosis) and entry by micropinocytosis in coated transport vesicles.

Abstract: Human interferon (HIF) preparations inhibited the propagation of Daudi cells in stationary suspension cultures, while a control preparation showed no such effect. The growth inhibition (= anticellular) activity of differently pretreated HIF preparations was determined by the reduction of14C-labelled thymidine (14C-TDR) uptake in a microassay system. These studies demonstrated that the degree of anticellular activity is directly proportional to the antiviral activity of different HIF preparations. These preparations were obtained from peripheral leukocytes (lHIF) or diploid fibroblasts (fHIF). Together with gel chromatography results, and the sensitivity of the anticellular activity to tryptic digestion and heat inactivation, these results suggest that the anticellularly active substance is a protein which is very similar to, or identical with, interferon.

Abstract: The results of the meetings of the International Committee on Taxonomy of Viruses, held in Madrid, September 1975, are briefly reported: rules of viral nomenclature, composition of the new Executive Committee, and a list of the names so far officially agreed.

Abstract: Venezuelan encephalitis (VEE) virus strains, which differ in virulence for adult hamsters, were compared with respect to (a) sensitivity to hamster interferon (IF)in vitro andin vivo and (b) induction of IF in plasma and target tissues (spleen, bone marrow and brain) following subcutaneous inoculation.In vitro, in cultures of a continuous line of hamster kidney cells, hamster interferon inhibited the replication of a benign VEE strain (BeAr 35,645) more than another benign strain (TC-83 vaccine) or two hamster-virulent strains (68 U 201 and Trinidad donkey).In vivo, in hamsters given poly I:poly C 24 hours before virus to induce interferon formation, BeAr 35,645 and TC-83 virus infections were prevented more frequently than infections with virulent strains Trinidad donkey and 68U201. Benign VEE strains BeAr 35,645 and TC-83 induced only slightly lower concentrations of IF in plasma, bone marrow, spleen and brain than virulent strains Trinidad donkey, 63Z21 and 68U201. However, concentrations of infectious BeAr 35,645 virus were significantly lower in these tissues than virulent strains, resulting in higher ratios of IF:infectious virus, suggesting efficient interferon induction. Benign strain TC-83 showed irregular relationships between IF and infectious virus in plasma or blood and tissues. Splenectomy significantly depressed plasma IF responses to TC-83 virus 20 to 30 hours after inoculation. Interferon appears to be a factor that influences virulence of VEE viruses for hamsters.

Abstract: The neuraminidases of different strains of influenza virus varied in their stability at 37 degrees C. The enzymes of the strains with N1 neuraminidases were found to be unstable during incubation at 37 degrees C whereas the enzymes of the strains with the N2 neuraminidases were stable. Among the strains with N2 neuraminidases, the enzymes of some strains were inactivated during dialysis at 37 degrees C whereas the enzymes of others were stable. This observed loss of enzyme activity during dialysis at 37 degrees C was not restricted to a single substrate as the same loss of enzyme activity was observed irrespective of the size of the substrate used in the assay. The enzymically inactive neuraminidase was found to be non-antigenic and non-immunogenic. The inactivation of the enzyme could be prevented by the addition of Ca++ but not Mg++. Out results suggest that Ca++ is essential for the stability of the enzyme at 37 degrees C. The results would also suggest that the enzymic, antigenic and immunogenic sites are either the same or very closely situated on the surface of the neuraminidase molecule.

Abstract: Analysis of total lipid, phospholipid and cholesterol distribution has been conducted in parallel on BHK 21/13S cells grown in suspension cultures, on purified Rubella virus and on cells infected by the virus. Extracellular virus was purified by use of a previously described procedure (3, 4).

Abstract: Infectious bronchitis virus was observed to enter cells of chicken chorioallantoic membrane by viropexis. There was no support for the suggestion that entry took place by fusion of viral and plasma membranes. The results of electron microscopy showed that virus attachment occurred both at 4° and at 37° C. Viropexis was not observed until the preparations were warmed. Similar results were obtained using chicken kidney cells. Quantitative data obtained from a plaque counting system employing chicken kidney cells indicated that attachment was the same at both temperatures and that some virus particles were taken up at 4° C.

Abstract: Sixteen cytomegalovirus (CMV) isolates from both ill and healthy patients were identified by the immunoperoxidase technique (IP). CMV detection was accomplished by direct examination of the primary isolate using either direct (DIP) or indirect immunoperoxidase (IIP) techniques. In thirteen of the isolates, confirmation of identification was achieved by indirect immunofluorescence (IFA) and by demonstration of herpes particles by electron microscopy (EM). Further, in four cases of non-CMV alterations in the tissue culture which might be confused with actual infection, the IP test was negative as were the confirmatory tests. The IIP is preferred over the DIP test since the latter shows a certain amount of background stain of uninfected cells. Tissue culture cells showing focal CMV cytopathic effect contained both nuclear and cytoplasmic inclusions stained by IP technique. Nonspecific staining was associated with cytoplasmic inclusion bodies. The IP technique can detect individual cell CMV infection at 24 hours when EM reveals only unenveloped viral particles. It is sensitive, specific, and allows direct identification of infected cells in the primary isolate in as little as 90 minutes. Furthermore, it can be performed in standard isolation tissue culture tubes, whereas IFA requires the transfer of the infected cells onto slides or the routine use of Leighton tubes.

Abstract: Nine serotypes of bovine adenovirus, five serotypes of ovine adenovirus, and four serotypes of porcine adenovirus were compared in reciprocal cross-neutralisation tests, to determine if viruses isolated from different species were indeed distinct serotypes. In addition, the above serotypes were tested for possible antigenic relationships with 28 of 32 human adenoviruses, by one-way cross neutralisation tests with human adenovirus antisera. The results indicated that all viruses tested were distinct serotypes. Ovine adenovirus types 4 and 5, until now not compared by neutralisation tests, were confirmed as separate serotypes.

Abstract: Bovine coronavirus readily multiplied and induced marked cytopathic effect in BEK-1 cultures, thus providing a sensitive, practical assay system for viral infectivity and neutralizing antibody and a satisfactory source of the virus.

Abstract: Several strains of human cytomegalovirus including recent isolates, were grown in epithelial cells derived from thyroid tissue. All the strains tested grew in these cultures without pre-treatment of the cells, and no difference in cytopathic effect was detected between strains of genital and non-genital origin. 4 strains of CMV were isolated directly from urine in thyroid cells; however the failure to isolate 6 further strains in these cultures from other specimens may indicate that a higher multiplicity of infection is required to infect epithelial than fibroblast cells.

Abstract: Human diploid BAMB cells with epitheloid morphology, which had been derived from amniotic fluid cells, were capable of supporting the replication of human cytomegalovirus (CMV), without prior treatment of the cells with halogenated pyrimidines. The growth of this virus in BAMB cells and in human diploid fibroblastoid (LEP) cells was compared in parallel tests. Virus replication was slower and less efficient in the former than in the latter system. The most characteristic morphological feature of the CMV-infected BAMB cells was the formation of multinucleated giant cells which frequently contained more than a hundred nuclei; such cells were not seen in LEP cultures. The development of ultrastructural changes was slower in BAMB cells than in LEP cells. The additional most marked differences concerned the place of viral envelopment and the production of cytoplasmic dense bodies. While in LEP cells most nucleocapsids were enveloped from the inner leaflet of the nuclear membrane, in the other system a great majority of the particles acquired their envelopes by budding into vacuoles. Cytoplasmic dense bodies were rare in infected LEP cells but very frequent in BAMB cells. Budding of these structures into vacuoles was also observed.

Abstract: Influenza C viruses did not possess neuraminidase activity when examined using either fetuin or sialyllactose as substrate. Purified preparations of influenza C virus inhibited hemagglutination by NWS hemagglutinin. The hemagglutination inhibiting activity was a bolished by treatment of influenza C virus with neuraminidase. These findings indicated the absence of neuraminidase activity on influenza C virus particles.

Abstract: Egg-grown infectious bronchitis virus, strain Beaudette, was concentrated and centrifuged on sucrose density gradients to separate the virus into five peaks with densities of 1.144, 1.160, 1.172, 1.191 and 1.218 g/cm3. All peaks retained infectivity, complement fixation activity and were labelled with 3H-uridine. Morphologically the densest peak consisted of very large virus particles and amorphous material, the other peaks consisted of mainly intact particles although small differences in size and pleomorphism were seen. Polyacrylamide gel electrophoresis of material from the density gradient peaks revealed four major polypeptides and at least 10 minor polypeptides. The proportions of the polypeptides were approximately similar for all peaks with the exception of the densest peak in which the major polypeptides were greatly reduced. The four major polypeptides had approximate molecular weights of 1. 52,000, 2. 45,000, 3. 34,000, 4. 32,000. The major polypeptides 1 and 4 were shown to be glycosylated as were two of the minor polypeptides.

Abstract: Three identical strains of an arbovirus were isolated from 475Ornithodoros papillipes ticks collected in June, 1972, in burrows of the great gerbil (Rhombomys opimus Licht., 1882) in the environs of Beshkent, Karshinsk steppe, Uzbek S.S.R. The isolate was found to range among flaviviruses. Complement-fixation, agar diffusion precipitation and neutralization tests is tissue culture and mice indicated a one-way antigenic relationship between the isolate and West Nile virus. However, the pattern of differences between them made it possible to consider the isolated agent as a new virus, “Karshi” virus. The results of electron microscopic studies of this virus are presented.

Abstract: BLV particles described as antigenically and in some respect biochemically different from known mammalian C-type particles do not show morphological distinctions from typical C-type particles.