Identification and differentiation of the nine African horse sickness virus serotypes by RT-PCR amplification of the serotype-specific genome segment2

This paper describes the first RT-PCR for discrimination of the nine Africa n horse sickness virus (AHSV) serotypes. Nine pairs of primers were designe d, each being specific for one AHSV serotype. The RT-PCR was sensitive and specific, providing serotyping within 24 h. Perfect agreement was recorded between the RT-PCR and virus neutralization for a coded panel of 56 AHSV re ference strains and field isolates. Serotyping was achieved successfully wi th live and formalin-inactivated AHSVs, with isolates of virus after low an d high passage through either tissue culture or suckling mouse brain, with viruses isolated from widely separated geographical areas and with viruses isolated up to 37 years apart. Overall, this RT-PCR provides a rapid and re liable method for the identification and differentiation of the nine AHSV s erotypes, which is vital at the start of an outbreak to enable the early se lection of a vaccine to control the spread of disease.