Crimean-Congo hemorrhagic fever virus entry into host cells occurs through the multivesicular body and requires ESCRT regulators.

Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne bunyavirus causing outbreaks of severe disease in humans, with a fatality rate approaching 30%. There are no widely accepted therapeutics available to prevent or treat the disease. CCHFV enters host cells through clathrin-mediated endocytosis and is subsequently transported to an acidified compartment where the fusion of virus envelope with cellular membranes takes place. To better understand the uptake pathway, we sought to identify host factors controlling CCHFV transport through the cell. We demonstrate that after passing through early endosomes in a Rab5-dependent manner, CCHFV is delivered to multivesicular bodies (MVBs). Virus particles localized to MVBs approximately 1 hour after infection and affected the distribution of the organelle within cells. Interestingly, blocking Rab7 activity had no effect on association of the virus with MVBs. Productive virus infection depended on phosphatidylinositol 3-kinase (PI3K) activity, which meditates the formation of functional MVBs. Silencing Tsg101, Vps24, Vps4B, or Alix/Aip1, components of the endosomal sorting complex required for transport (ESCRT) pathway controlling MVB biogenesis, inhibited infection of wild-type virus as well as a novel pseudotyped vesicular stomatitis virus (VSV) bearing CCHFV glycoprotein, supporting a role for the MVB pathway in CCHFV entry. We further demonstrate that blocking transport out of MVBs still allowed virus entry while preventing vesicular acidification, required for membrane fusion, trapped virions in the MVBs. These findings suggest that MVBs are necessary for infection and are the sites of virus-endosome membrane fusion.

Epidemiology of Viliuisk encephalomyelitis in Eastern Siberia.

BACKGROUND: Viliuisk encephalomyelitis is a disorder that starts, in most cases, as an acute meningoencephalitis. Survivors of the acute phase develop a slowly progressing neurologic syndrome characterized by dementia, dysarthria, and spasticity. An epidemic of this disease has been spreading throughout the Yakut Republic of the Russian Federation. Although clinical, neuropathologic, and epidemiologic data suggest infectious etiology, multiple attempts at pathogen isolation have been unsuccessful. METHODS: Detailed clinical, pathologic, laboratory, and epidemiologic studies have identified 414 patients with definite Viliuisk encephalomyelitis in 15 of 33 administrative regions of the Yakut Republic between 1940 and 1999. All data are documented in a Registry. RESULTS: The average annual Viliuisk encephalomyelitis incidence rate at the height of the epidemic reached 8.8 per 100,000 population and affected predominantly young adults. The initial outbreak occurred in a remote isolated area of the middle reaches of Viliui River; the disease spread to adjacent areas and further in the direction of more densely populated regions. The results suggest that intensified human migration from endemic villages led to the emergence of this disease in new communities. Recent social and demographic changes have presumably contributed to a subsequent decline in disease incidence. CONCLUSIONS: Based on the largest known set of diagnostically verified Viliuisk encephalomyelitis cases, we demonstrate how a previously little-known disease that was endemic in a small indigenous population subsequently reached densely populated areas and produced an epidemic involving hundreds of persons.

Filovirus RefSeq entries: evaluation and selection of filovirus type variants, type sequences, and names.

Sequence determination of complete or coding-complete genomes of viruses is becoming common practice for supporting the work of epidemiologists, ecologists, virologists, and taxonomists. Sequencing duration and costs are rapidly decreasing, sequencing hardware is under modification for use by non-experts, and software is constantly being improved to simplify sequence data management and analysis. Thus, analysis of virus disease outbreaks on the molecular level is now feasible, including characterization of the evolution of individual virus populations in single patients over time. The increasing accumulation of sequencing data creates a management problem for the curators of commonly used sequence databases and an entry retrieval problem for end users. Therefore, utilizing the data to their fullest potential will require setting nomenclature and annotation standards for virus isolates and associated genomic sequences. The National Center for Biotechnology Information's (NCBI's) RefSeq is a non-redundant, curated database for reference (or type) nucleotide sequence records that supplies source data to numerous other databases. Building on recently proposed templates for filovirus variant naming [ ()////-], we report consensus decisions from a majority of past and currently active filovirus experts on the eight filovirus type variants and isolates to be represented in RefSeq, their final designations, and their associated sequences.

A novel, killed-virus nasal vaccinia virus vaccine.

Live-virus vaccines for smallpox are effective but have risks that are no longer acceptable for routine use in populations at minimal risk of infection. We have developed a mucosal, killed-vaccinia virus (VV) vaccine based on antimicrobial nanoemulsion (NE) of soybean oil and detergent. Incubation of VV with 10% NE for at least 60 min causes the complete disruption and inactivation of VV. Simple mixtures of NE and VV (Western Reserve serotype) (VV/NE) applied to the nares of mice resulted in both systemic and mucosal anti-VV immunity, virus-neutralizing antibodies, and Th1-biased cellular responses. Nasal vaccination with VV/NE vaccine produced protection against lethal infection equal to vaccination by scarification, with 100% survival after challenge with 77 times the 50% lethal dose of live VV. However, animals protected with VV/NE immunization did after virus challenge have clinical symptoms more extensive than animals vaccinated by scarification. VV/NE-based vaccines are highly immunogenic and induce protective mucosal and systemic immunity without the need for an inflammatory adjuvant or infection with live virus.