Autophagy can play an important part in protecting host cells during virus infection, and several viruses have developed strategies by which to evade or even exploit this homeostatic pathway. Tissue culture studies have shown that poliovirus, an enterovirus, modulates autophagy. Herein, we report on in vivo studies that evaluate the effects on autophagy of coxsackievirus B3 (CVB3). We show that in pancreatic acinar cells, CVB3 induces the formation of abundant small autophagy-like vesicles and permits amphisome formation. However, the virus markedly, albeit incompletely, limits the fusion of autophagosomes (and/or amphisomes) with lysosomes, and, perhaps as a result, very large autophagy-related structures are formed within infected cells; we term these structures megaphagosomes. Ultrastructural analyses confirmed that double-membraned autophagy-like vesicles were present in infected pancreatic tissue and that the megaphagosomes were related to the autophagy pathway; they also revealed a highly organized lattice, the individual components of which are of a size consistent with CVB RNA polymerase; we suggest that this may represent a coxsackievirus replication complex. Thus, these in vivo studies demonstrate that CVB3 infection dramatically modifies autophagy in infected pancreatic acinar cells.Macroautophagy-henceforth referred to as autophagy-is an intracellular process that is important for cellular differentiation, homeostasis, and survival. Through autophagy, longlived cytosolic proteins and organelles become encapsulated within double-membraned vesicles, called autophagosomes, which fuse with lysosomes to facilitate degradation of protein and cellular organelles and to promote nutrient recycling/regeneration. Autophagy plays a key role in the host immune response to infection by viruses, bacteria, fungi, and parasites (reviewed in references 10 and 62). Within virus-infected cells, whole virions and/or viral proteins and nucleic acids are captured inside autophagosomes and degraded (following lysosomal fusion) through the process of xenophagy. Moreover, autophagosome fusion with the endosomal/lysosomal pathway facilitates Toll-like receptor recognition of viral materials and delivers endogenous cytosolic viral proteins to the major histocompatibility complex (MHC) class II antigen presentation pathway, which in turn may help to trigger activation of innate immunity (and type I interferon production) and promote antigen presentation to virus-specific CD4 ϩ T cells (reviewed in references 9, 41, 44, 47, 72, and 90). A recent study has shown that autophagy is also involved in the processing and presentation of MHC class I-restricted viral epitopes (13).Given the importance of autophagy in antiviral immunity, it is perhaps not surprising that viruses have evolved mechanisms to evade and/or subvert this pathway (reviewed in references 9, 11, 14, 35, 37, 60, 61, and 77). Several members of the herpesvirus family, most notably herpes simplex virus type 1, inhibit autophagy within an infected cell and encode prote...

Highlights d Survivors produce GPC-B antibodies targeting nearidentical Lassa virus GP epitopes d Lassa neutralization potency and breadth tied to shared residues in GPC-B antibodies d Lassa GP glycans mask GPC-B epitope d Removal of GP glycans enhances interaction with germline antibody progenitors

Coxsackievirus type B (CVB) infection of the pancreas induces a massive cellular infiltrate composed of natural killer cells, T cells, and macrophages and leads to the destruction of exocrine tissue. The physiological manifestations of pancreatic CVB infection are correlated with viral tropism; the virus infects acinar cells but spares the islets of Langerhans. Here we evaluate the mechanisms underlying pancreatic inflammation and destruction and identify the determinants of viral tropism. T-cell-mediated immunopathology has been invoked, along with direct virus-mediated cytopathicity, to explain certain aspects of CVB-induced pancreatic disease. However, we show here that in the pancreas, the extent of inflammation and tissue destruction appears unaltered in the absence of the cytolytic protein perforin; these findings exclude any requirement for perforin-mediated lysis by natural killer cells or cytotoxic T cells in CVB3-induced pancreatic damage. Furthermore, perforin-mediated cytotoxic T-cell activity does not contribute to the control of CVB infection in this organ. In addition, we demonstrate that the recently identified coxsackie-adenovirus receptor is expressed at high levels in acinar cells but is barely detectable in islets, which is consistent with its being a major determinant of virus tropism and, therefore, of disease. However, further studies using various cell lines of pancreatic origin reveal secondary determinants of virus tropism.

Coxsackieviruses are important human pathogens, frequently causing myocarditis , pancreatitis , and a variety of less severe diseases. B lymphocytes appear central to the interaction between these viruses and their mammalian hosts , because agammaglobulinemic humans , genetically incapable of antibody production , are susceptible to chronic infections by coxsackieviruses and related enteroviruses , such as poliovirus and echovirus. However , recent studies show that Type B coxsackievirus (CVB) infects B lymphocytes soon after infection , suggesting the possibility that these cells may play some role in virus dissemination and/or that the virus may be able to modulate the host immune response. We analyzed the role of B lymphocytes in CVB infection and confirmed that CVB infects B lymphocytes , and extended these findings to show that this is a productive infection involving approximately 1 to 10% of the cells; however , infectious center assays show that other splenocytes are infected at approximately the same frequency. Virus is readily detectable by in situ hybridization in the spleen of immunocompetent mice but is difficult to detect in mice deficient in B cells (BcKO mice) , consistent with much of the splenic signal being the result of B cell infection. Surprisingly , given the extent of their infection, B cells express barely detectable levels of the murine coxsackievirus-adenovirus receptor (mCAR) , suggesting that another means of cell entry may be used. We found no evidence of B cell depletion following CVB infection , indicating that this is not the explanation for the transient immunosuppression previously reported. Virus replication and dissemination are slightly delayed in BcKO mice , consistent with B cells' playing a role as an important early target of infection and/or a means to distribute the virus to many tissues. In addition , we show that BcKO mice recapitulate a central feature of human agammaglobulinemia: CVB establishes chronic infection in a variety of organs (heart , liver , brain , kidney , lung , pancreas , spleen). In most of these tissues the viral titers remain high Coxsackieviruses are members of the family Picornaviridae and lie in the enterovirus genus along with polioviruses, echoviruses, and unclassified enteroviruses. There are two types of coxsackievirus, A and B, classified by their pathogenicity in newborn mice, 1 and within each type are several strains. Type B coxsackieviruses (CVB) are common causes of human disease. As the genus name suggests, they replicate in the gastro-intestinal tract, but they are not restricted to this site; they also infect, for example, skeletal muscle (causing intercostal myalgia (Bornholm disease) and polymyositis), cardiac muscle (with resulting myocarditis), and acinar cells in the exocrine pancreas (causing fulminant pancreatitis), as well as various cells of the immune system. Foci of infection can also be found in the liver, kidney, central nervous system, spleen, and elsewhere. Enteroviruses infect humans with epidemic frequency, reflect...