CAPSID PROTEIN-COMPOSITION OF REFERENCE STRAINS AND WILD ISOLATES OF HUMAN ASTROVIRUSES

Astroviruses are small RNA viruses that are frequently associated with gastroenteritis in humans and animals. Despite much work on the genet ic analysis of astrovirus strains, little progress has been made in th e characterization of the proteins composing mature virions. We have a nalyzed the capsid protein composition of the reference strains and se veral wild isolates of human astroviruses using high-resolution polyac rylamide gradient gels. For reference strains of the seven serotypes a nalyzed, a consistent pattern of three infection-specific proteins-des ignated P1, P2, and P3-was generally observed. The strains could be di vided into two groups, based upon the reactivity of these proteins in immune precipitation assays that used homologous rabbit serum. One gro up included reference types 1-4 for which all three proteins were prec ipitated by homologous rabbit sera; for the other group, types 5-7, on ly proteins P2 and P3 were precipitated. When wild isolates from aroun d the world were compared to the reference strains, a correlation betw een genetic type and the pattern of protein sizes and immune reactivit y was observed for strains of the common types (1-4). Strains of types 2 and 4 consistently exhibited P3 proteins larger than those of types 1 and 3. Unusual patterns of proteins or immune reactivity were detec ted in strains of types 5-7, indicating that there may be incomplete p rocessing of the capsid precursor during growth in cell culture. (C) 1 997 Elsevier Science B.V.