An electron microscopic study of the surface structures and hemadsorption on chick embryo cells infected with rabies virus

The Serendipity of Viral Trans-Neuronal Specificity: More Than Meets the Eye

Trans-neuronal viruses are frequently used as neuroanatomical tools for mapping neuronal circuits. Specifically, recombinant one-step rabies viruses (RABV) have been instrumental in the widespread application of viral circuit mapping, as these viruses have enabled labs to map the direct inputs onto defined cell populations. Within the neuroscience community, it is widely believed that RABV spreads directly between neurons via synaptic connections, a hypothesis based principally on two observations. First, the virus labels neurons in a pattern consistent with known anatomical connectivity. Second, few glial cells appear to be infected following RABV injections, despite the fact that glial cells are abundant in the brain. However, there is no direct evidence that RABV can actually be transmitted through synaptic connections. Here we review the immunosubversive mechanisms that are critical to RABV’s success for infiltration of the central nervous system (CNS). These include interfering with and ultimately killing migratory T cells while maintaining levels of interferon (IFN) signaling in the brain parenchyma. Finally, we critically evaluate studies that support or are against synaptically-restricted RABV transmission and the implications of viral-host immune responses for RABV transmission in the brain.

Cytovillin and other microvillar proteins of human choriocarcinoma cells

Microvilli were isolated from cultured human JEG-3 choriocarcinoma cells using a gentle shearing method. The protein components of the isolated microvilli were examined by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. The major Mr 42,000 and Mr 100,000 polypeptide bands reacted with anti-actin and anti-alpha-actinin antisera, respectively. Extraction of the isolated JEG-3 microvilli with Triton X-100 left an insoluble cytoskeletal residue containing mainly actin, alpha-actin, and polypeptides of Mr 200,000, 55,000 and 35,000. The Mr 35,000 polypeptide remained insoluble only at high concentrations of free Ca2+. Immunoblotting analysis of the JEG-3 microvilli indicated that they were devoid of tropomyosin, although the total JEG-3 protein lysates gave a strong positive reaction with anti-tropomyosin antiserum. The different subcellular localization of cytovillin and tropomyosin was also shown by indirect immunofluorescence microscopy. Cytovillin, an Mr 75,000 microvillus-specific membrane protein of JEG-3 cells, existed in an oligomeric form (dimer or trimer) as shown by gel filtration of Triton X-100 solubilized microvillar proteins and by native polyacrylamide gel electrophoresis of purified cytovillin. Disulfide bridges were not involved in the aggregation, because the mobility of cytovillin was similar under reducing and nonreducing conditions in SDS-PAGE. Cytovillin was shown to be closely related to ezrin, a minor component of chicken intestinal brush border microvilli.

Isolation and characterization of rotavirus from feral pigeon in mammalian cell cultures

Avian rotaviruses were isolated from feral pigeon faeces treated with trypsin using roller tube cultures of mammalian cells. Two pigeon strains, designated as strains PO-8 and PO-13, produced a marked cytopathic effect (CPE), small intracytoplasmic inclusion bodies and high titres of infectious particles in infected MA-104 and MDBK cell lines without cell adaptation and roller drum apparatus. The pigeon rotaviruses shared a common group specific antigen with the Lincoln strain of bovine rotavirus by indirect immunofluorescence, but differed from both the Lincoln strain and the Wa strain of human rotavirus in neutralization tests. The RNA segment profile of this virus on polyacrylamide gel electrophoresis differed from that of group A mammalian rotaviruses. The results of a serological survey suggested that antibody to pigeon rotaviruses was widespread in avian species in Japan.