CD46

Abstract: Measles virus continues to be a major killer of children, claiming roughly one million lives a year Measles virus infection causes profound immunosuppression, which makes measles patients susceptible to secondary infections accounting for high morbidity and mortality The Edmonston strain of measles virus, and vaccine strains derived from it, use as a cellular receptor human CD46 (refs 3, 4), which is expressed on all nucleated cells; however, most clinical isolates of measles virus cannot use CD46 as a receptor Here we show that human SLAM (signalling lymphocyte-activation molecule; also known as CDw150), a recently discovered membrane glycoprotein expressed on some T and B cells, is a cellular receptor for measles virus, including the Edmonston strain Transfection with a human SLAM complementary DNA enables non-susceptible cell lines to bind measles virus, support measles virus replication and develop cytopathic effects The distribution of SLAM on various cell lines is consistent with their susceptibility to clinical isolates of measles virus The identification of SLAM as a receptor for measles virus opens the way to a better understanding of the pathogenesis of measles virus infection, especially the immunosuppression induced by measles virus

Abstract: The complement system is an evolutionary old and crucial component of innate immunity key to the detection and removal of invading pathogens. It was initially discovered as a liver-derived sentinel system circulating in serum, the lymph and interstitial fluids that mediates the opsonization and lytic killing of bacteria, fungi and viruses and the initiation of the general inflammatory responses. Although work performed specifically in the last five decades identified complement also as a critical instructor of adaptive immunity – indicating that complement’s function is likely broader than initially anticipated - the dominant opinion among researchers and clinicians was that the key complement functions were in principle defined. However, there is now a growing realization that complement activity goes well beyond ‘classic’ immune functions and that this system is also required for normal (neuronal) development and activity and general cell and tissue integrity and homeostasis. Furthermore, the recent discovery that complement activation is not confined to the extracellular space but occurs within cells led to the surprising understanding that complement is involved in the regulation of basic processes of the cell, particularly those of metabolic nature – mostly via novel crosstalks between complement and intracellular sensor, and effector, pathways that had been overlooked because of their spatial separation. These paradigm shifts in the field led to a renaissance in complement research and provide new platforms to now better understand the molecular pathways underlying the wide-reaching effects of complement functions in immunity and beyond. In this review, we will cover the current knowledge about complement’s emerging relationship with the cellular metabolism machinery with a focus on the functional differences between serum-circulating versus intracellularly active complement during normal cell survival and induction of effector functions. We will also discuss how taking a closer look into the evolution of key complement components not only made the functional connection between complement and metabolism rather ‘predictable’ but how it may also give clues for the discovery of additional roles for complement in basic cellular processes.

Abstract: Group B adenoviruses, a subgenus of human Adenoviridae, are associated with a variety of often-fatal illnesses in immunocompromised individuals, including bone marrow transplant recipients and cancer and AIDS patients. Recently, group B adenovirus derivatives have gained interest as attractive gene therapy vectors because they can transduce target tissues, such as hematopoietic stem cells, dendritic cells and malignant tumor cells, that are refractory to infection by commonly used adenoviral vectors. Whereas many adenoviruses infect cells through the coxsackievirus and adenovirus receptor (CAR), group B adenoviruses use an alternate, as-yet-unidentified cellular attachment receptor. Using mass spectrometric analysis of proteins interacting with a group B fiber, we identified human CD46 as a cellular attachment receptor for most group B adenoviruses. We show that ectopic expression of human CD46 rendered nonhuman cells susceptible to infection with group B viruses in vitro and in vivo. In addition, both siRNA-mediated knockdown of CD46 and a soluble form of CD46 blocked infection of human cell lines and primary human cells. The discovery that group B adenoviruses use CD46, a ubiquitously expressed complement regulatory protein, as a cellular attachment receptor elucidates the diverse clinical manifestation of group B virus infections, and bears directly on the application of these vectors for gene therapy.