Detection by Immune Electron Microscopy of the Snow Mountain Agent of Acute Viral Gastroenteritis

Abstract

An extensive outbreak of acute gastroenteritis of unknown etiology occurred at Snow Mountain, Colorado, in December 1976. Virus-like particles, 27 nm in diameter, were observed by electron microscopy in two of five stool specimens from individuals in the outbreak. Oral administration of a filtrate from one of the specimens induced disease in nine of 12 normal volunteers. Experimentally induced illness was similar to that observed during the outbreak. Stool specimens examined by immune electron microscopy revealed 27-nm virus-like particles in three of nine ill volunteers at the onset of illness. When the particles were used as a source of antigen, increases in levels of serum antibody were demonstrated in persons with either experimentally induced or naturally occurring illness. Therefore, it is likely that this virus-like particle is the etiologic agent of the Snow Mountain outbreak. The Snow Mountain agent appears to be morphologically similar to, but antigenically distinct from, the Norwalk and Hawaii agents by immune electron microscopy and may represent an additional antigenic type among the agents that resemble the Norwalk particle.

Development of an ELISA to detect MX virus, a human calicivirus in the Snow Mountain agent genogroup

“…The antisera derived from the baculovirus antigen are of known specificity and of unlimited supply. One difference between our observations and those of previous reports is that HA, previously found to be antigenically distinct from SMA by IEM and cross-challenge studies (Wyatt et al, 1974;Dolin et al, 1982), now would be classified in the same subgroup with SMA. We believe these differences will be resolved when new reagents are used.…”

“…The Sapporo genogroup was clearly distinct from NV-and SMA genogroups by the rNV and rMX ELISAs, however, type-specific assays for this genogroup remain to be developed. In addition, three antigenic types were described in the US (Wyatt et al, t974;Dolin et al, 1982), four serotypes were reported in the UK (Lewis, 1990(Lewis, , 1991 and up to nine serotypes were found in Japan (Okada et al, 1990). A worldwide collaboration utilizing a single test will be necessary to clarify the antigenic classification of HuCVs.…”

Human viral gastroenteritis

“…and Norwalk-like viruses (6,87,187,278,401), caliciviruses (112,231), astroviruses, (229,230), and possibly coronaviUntil 15 years ago, the causes of acute nonbacterial ruses (322). The common enteroviruses are associated with gastroenteritis were unknown.…”

“…However, some are antigenically similar and others are antigenically distinct from the Norwalk agent. These other agents, discovered in the 1970s, include the Hawaii agent (401), the Montgomery County agent (356), discovered in Maryland, and the Snow Mountain (SM) agent, discovered in Colorado (87). These viruses, including the Norwalk agent, cannot be cultivated in vitro, so that little is known of their biophysical and biochemical characteristics.…”

Small Round Structured Virus Associated With an Outbreak of Acute Gastroenteritis in Chiba, Japan

“…(2), astrovirus (3), Hawaii agent (4) , Snow Mountain agent (5), and Otofuke agent (6). These viruses have not been successfully propagated in cell cultures and therefore have not been characterized in detail biologically or biochemically.…”