Neurotropic virus tracing suggests a membranous-coating-mediated mechanism for transsynaptic communication.

Swine hemagglutinating encephalomyelitis virus (HEV) has been shown to have a capability to propagate via neural circuits to the central nervous system after peripheral inoculation, resulting in acute deadly encephalomyelitis in natural host piglets as well as in experimental younger rodents. This study has systematically examined the assembly and dissemination of HEV 67N in the primary motor cortex of infected rats and provides additional evidence indicating that membranous-coating-mediated endo-/exocytosis can be used by HEV for its transsynaptic transfer. In addition, our results suggested that this transsynaptic pathway could adapted for larger granular materials, such as viruses. These findings should help in understanding the mechanisms underlying coronavirus infections as well as the intercellular exchanges occurring at the synaptic junctions.

Reverse transcription-loop-mediated isothermal amplification for the detection of rodent coronaviruses.

Mouse hepatitis virus (MHV) is one of the most prevalent viruses detected in laboratory mouse colonies. Enterotropic strains predominate in natural infections, and molecular techniques for the detection of MHV shedding in feces are powerful enough to diagnose active infections. A reverse transcription-loop-mediated isothermal amplification (RT-LAMP) technique was developed for the detection of rodent coronaviruses within 90 min. The specificity of this technique was confirmed by its ability to detect all 17 different strains of MHV and 6 strains of rat coronaviruses as well as its failure to detect human, bovine, and porcine coronaviruses nonspecifically. The sensitivity of RT-LAMP was 3.2-fold higher than that of reverse transcription-polymerase chain reaction (RT-PCR) and 31.6-fold lower than that of nested RT-PCR. An evaluation of the diagnostic performance of RT-LAMP performed in duplicate using mouse fecal specimens showed that the sensitivity and specificity with respect to nested RT-PCR were 85.7% and 100%, respectively. RT-LAMP assays would be suitable for monitoring active MHV infection in mouse colonies.

Coronavirus infection of rat dorsal root ganglia: ultrastructural characterization of viral replication, transfer, and the early response of satellite cells.

Swine hemagglutinating encephalomyelitis virus (HEV) has been shown to have a capability to gain access to the cell bodies of sensory neurons after peripheral inoculation, resulting in ganglionic infection. It is not clearly understood how this virus is replicated within and released from the sensory neurons, and it remains to know how satellite cells response to the HEV invasion. By ultrastructurally examining HEV-infected rat dorsal root ganglia, we found that HEV in the cell bodies of infected neurons budded from endoplasmic reticulum-Golgi intermediate compartments, and were assembled either individually within small vesicles or in groups within large vesicles. The progeny virions were released from the sensory neurons mainly by smooth-surfaced vesicle-mediated secretory pathway, which occurred predominantly at the perikaryal projections and infoldings of sensory neurons. Released HEV particles were subsequently taken up by the adjacent satellite cells. Almost all virus particles in the cytoplasm of satellite cells were contained in groups within vesicles and lysosome-like structures, suggesting that these glial cells may restrict the local diffusion of HEV. These observations give some insights into the pathogenesis of coronavirus infection and are thought to help understand the interactions between sensory neurons and their satellite cells.

Hemagglutinating encephalomyelitis coronavirus infection in pigs, Argentina.

We describe an outbreak of vomiting, wasting, and encephalomyelitis syndrome in piglets in Argentina, caused by porcine hemagglutinating encephalomyelitis coronavirus (PHE-CoV) infection. Diagnosis was made by epidemiologic factors, pathologic features, immunohistochemistry, reverse transcription-PCR, and genomic sequencing. This study documents PHE-CoV infection in South America.