A recombinant rabies virus (RV) carrying two identical glycoprotein (G) genes (SPBNGA-GA) was constructed and used to determine the effect of RV G overexpression on cell viability and immunity. Immunoprecipitation analysis and flow cytometry showed that tissue culture cells infected with SPBNGA-GA produced, on average, twice as much RV G as cells infected with RV carrying only a single RV G gene (SPBNGA). The overexpression of RV G in SPBNGA-GA-infected NA cells was paralleled by a significant increase in caspase 3 activity followed by a marked decrease in mitochondrial respiration, neither of which was observed in SPBNGA-infected cells. Furthermore, fluorescence staining and confocal microscopy revealed an increased extent of apoptosis and markedly reduced neurofilament and F actin in SPBNGA-GA-infected primary neuron cultures compared with neuronal cells infected with SPBNGA, supporting the concept that RV G or motifs of the RV G gene trigger the apoptosis cascade. Mice immunized with SPBNGA-GA showed substantially higher antibody titers against the RV G and against the nucleoprotein than SPBNGA-immunized mice, suggesting that the speed or extent of apoptosis directly determines the magnitude of the antibody response.

Chikungunya virus (CHIKV) has recently re-emerged causing millions of infections in countries around the Indian Ocean. While CHIKV has a broad host cell range and productively infects a number of different cell types, macrophages have been identified as a potential viral reservoir serving to increase the duration of symptoms. To date no CHIKV interacting protein has been characterized and this study sought to identify CHIKV binding proteins expressed on target cell membranes. Two-dimensional virus overlay identified prohibitin (PHB) as a microglial cell expressed CHIKV binding protein. Co-localization, co-immunoprecipitation as well as antibody and siRNA mediated infection inhibition studies all confirmed a role for PHB in mediating internalization of CHIKV into microglial cells. PHB is the first identified CHIKV receptor protein, and this study is evidence that PHB may play a role in the internalization of multiple viruses.

Attenuated tissue culture-adapted and natural street rabies virus (RV) strains differ greatly in their neuroinvasiveness. To identify the elements responsible for the ability of an RV to enter the CNS from a peripheral site and to cause lethal neurological disease, we constructed a full-length cDNA clone of silver-haired bat-associated RV (SHBRV) strain 18 and exchanged the genes encoding RV proteins and genomic sequences of this highly neuroinvasive RV strain with those of a highly attenuated nonneuroinvasive RV vaccine strain (SN0). Analysis of the recombinant RV (SB0), which was recovered from SHBRV-18 cDNA, indicated that this RV is phenotypically indistinguishable from WT SHBRV-18. Characterization of the chimeric viruses revealed that in addition to the RV glycoprotein, which plays a predominant role in the ability of an RV to invade the CNS from a peripheral site, viral elements such as the trailer sequence, the RV polymerase, and the pseudogene contribute to RV neuroinvasiveness. Analyses also revealed that neuroinvasiveness of an RV correlates inversely with the time necessary for internalization of RV virions and with the capacity of the virus to grow in neuroblastoma cells.reverse genetics ͉ pathogenicity ͉ internalization

In the last few years, chikungunya has become a major problem in Southeast Asia, with large numbers of cases being reported in Singapore, Malaysia, and Thailand. Much of the current epidemic of chikungunya in Southeast Asia is being driven by the emergence of a strain of chikungunya virus that originated in Africa and spread to islands in the Indian Ocean, as well as to India and Sri Lanka, and then onwards to Southeast Asia. There is currently no specific treatment for chikungunya and no vaccine is available for this disease. This review seeks to provide a short update on the reemergence of chikungunya in Southeast Asia and the prospects for control of this disease.

While the glycoprotein (G) of rabies virus (RV) is known to play a predominant role in the pathogenesis of rabies, the function of the RV matrix protein (M) in RV pathogenicity is not completely clear. To further investigate the roles of these proteins in viral pathogenicity, we constructed chimeric recombinant viruses by exchanging the G and M genes of the attenuated SN strain with those of the highly pathogenic SB strain. Infection of mice with these chimeric viruses revealed a significant increase in the pathogenicity of the SN strain bearing the RV G from the pathogenic SB strain. Moreover, the pathogenicity was further increased when both G and M from SB were introduced into SN. Interestingly, the replacement of the G or M gene or both in SN by the corresponding genes of SB was associated with a significant decrease in the rate of viral replication and viral RNA synthesis. In addition, a chimeric SN virus bearing both the M and G genes from SB exhibited more efficient cell-to-cell spread than a chimeric SN virus in which only the G gene was replaced. Together, these data indicate that both G and M play an important role in RV pathogenesis by regulating virus replication and facilitating cell-to-cell spread.Rabies virus (RV), the etiological agent of one of the oldest recognized infectious diseases, almost always causes a fatal encephalomyelitis in several species of mammals, including humans (4). RV, the prototype of the Lyssavirus genus of the family Rhabdoviridae, is an enveloped, nonsegmented, negative-stranded RNA virus. RV has a simple genome of about 12 kb encoding five proteins: the nucleoprotein (N), the phosphoprotein (P), the matrix protein (M), the glycoprotein (G), and the RNA-dependent RNA polymerase (L). The viral RNA, which is always encapsidated by N, forms the ribonucleoprotein (RNP), which is the template for viral replication and transcription (2). The RNP together with P and L forms the viral replication complex, which is surrounded by the host cell-derived membrane that also contains G. M has been proposed to bridge the RNP and the cytoplasmic domain (CD) of RV G to form the bullet-shaped virion (22).The RV G, which is organized as a trimer, is the sole protein exposed on the surface of the virion. RV G interacts with cellular receptors (14,17,32,33), mediates pH-dependent fusion, and promotes viral entry from a peripheral site into the nervous system (19). Moreover, RV G is involved in the transsynaptic spread within the central nervous system (3, 7, 16). Although RV pathogenicity is a multigenic trait (10), RV G is the major contributor to the pathogenicity of a particular RV (5,6,10,15,21,23,29,30,34). The efficient interaction of RV G with putative host cellular receptors can promote effective virus uptake, resulting in increased virulence. Pathogenic RVs reportedly use different receptors and routes of entry than nonpathogenic derivatives (3,16). Differences in the distributions of various RV strains in the brain are determined at least in part by the RV G (35), and the RV G's of p...