Characterisation of a South African human astrovirus as type 8 by antigenic and genetic analyses

Abstract Human astroviruses (HAstV) can, on the basis of immunoassays using type‐specific rabbit antisera, be classified into eight serotypes that correlate with genotypes. Very few isolates of HAstV type 8 have been described and there is a paucity of data available with regard to the antigenic and genetic relationships between HAstV type 8 (HAstV‐8) and HAstV types 1 (HAstV‐1) to 7 (HAstV‐7). A wild‐type HAstV from a South African paediatric patient with diarrhoea was analysed antigenically, by immune electron microscopy and enzyme immunoassay, and genetically in selected regions of the ORF1a, ORF1b and ORF2 and characterised as a HAstV‐8. This HAstV‐8 strain exhibited greatest homology with HAstV‐4 in the 5′ end of the capsid gene and ORF1a and 1b, and greatest homology with HAstV‐5 in the 3′ end of the capsid region. This study confirms, by both antigenic and genetic analyses, that HAstV‐8 represents a distinct antigenic and genotype and is the first report of a HAstV‐8 from a hospitalised paediatric patient with diarrhoea in southern Africa. J. Med. Virol. 64:256–261, 2001. © 2001 Wiley‐Liss, Inc.