We report the identification of a neurotropic astrovirus associated with encephalitis in a sheep. This virus is genetically almost identical to an astrovirus recently described in neurologically diseased cattle. The similarity indicates that astroviruses of the same genotype may cause encephalitis in different species.

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In March 2022, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. The phylum was expanded by two new families (bunyaviral Discoviridae and Tulasviridae), 41 new genera, and 98 new species. Three hundred forty-nine species were renamed and/or moved. The accidentally misspelled names of seven species were corrected. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.

Two new astrovirus assays, a rapid biotin-avidin enzyme immunoassay (EIA) and RNA probe hybridization, were developed and compared with an established astrovirus assay, an indirect EIA, and immune electron microscopy. Sensitivity and specificity were evaluated by using a screening panel of 22 astrovirus-positive and 305 astrovirus-negative fecal specimens. The biotin-avidin assay was equivalent in performance to the reference indirect assay, and both could detect about 10 ng of viral protein. Although the probe was more sensitive than either EIA and could detect higher dilutions of virus in tissue culture and stool specimens, it did not detect more astrovirus-positive fecal specimens. Of the 22 astrovirus-positive specimens detected by the EIAs, 20 were confirmed by immune electron microscopy with hyperimmune rabbit antiserum. To determine the usefulness of EIAs for large epidemiologic studies, EIAs were used to screen 1,289 stool specimens from three studies of children with and without diarrhea. Astrovirus was detected in 3.5% of specimens from children with diarrhea and 1.9% of specimens from those without diarrhea. Our results indicate that the biotin-avidin EIA is an efficient, sensitive, and specific method for routinely screening large numbers of fecal samples and that its application in epidemiologic studies may yield higher rates of astrovirus infection than have been found previously by other methods. Astroviruses were first described in 1975 by Appleton and Higgins (1), who examined stool samples from infants with gastroenteritis by electron microscopy. Because of the characteristic starlike appearance of these 28to 30-nm particles, the name "astrovirus" was suggested by Madeley and Cosgrove (18). Astroviruses appear to occur worldwide and have been detected in the People's Republic of China (29), Japan (11), Thailand (7), Australia (5), South Africa (27), Malawi (24), Italy (2), Sweden (3), the United Kingdom (19), and the United States (15, 16, 23, 25). These reports have generally been associated with epidemic gastroenteritis in institutions with infants or the elderly and also with endemic illness in young children. The incubation period is typically 3 to 4 days, and illness is characterized by fever, headache, diarrhea, malaise, and occasional vomiting. Virus excretion can persist for up to 12 days (21). Astrovirus can be transmitted by food and water (13), although person-to-person transmission is the more likely cause in institutional settings where outbreaks have occurred. Nosocomial astrovirus infections have been docu

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