Ft. Vreede et H. Huismans, CLONING, CHARACTERIZATION AND EXPRESSION OF THE GENE THAT ENCODES THEMAJOR NEUTRALIZATION-SPECIFIC ANTIGEN OF AFRICAN HORSESICKNESS VIRUS SEROTYPE-3, Journal of General Virology, 75, 1994, pp. 3629-3633
The gene encoding the outer capsid protein, VP2, of African horsesickn
ess virus serotype 3 (AHSV-3) has been sequenced in its entirety from
cDNA clones of the segment 2 RNA, and compared with the previously pub
lished VP2 gene sequence of AHSV-4. AHSV-3 genome segment 2 was shown
to be 3221 nucleotides in length, encoding a protein of 1057 amino aci
ds with a 50.5 % identity to the amino acid sequence of AHSV-4 VP2. Tw
o areas of high variability (approximately 35 % identity) were identif
ied. The N-proximal variable region (amino acids 128 to 309) exhibited
significant hydrophilicity, suggesting a possible role in the determi
nation of the serotype-specific immune response. VP2 of AHSV-3 has fur
thermore been expressed in a baculovirus expression system. The expres
sed protein was shown to react specifically with an anti-AHSV-3 serum
in Western blots. Antibodies raised in rabbits and guinea-pigs against
the recombinant VP2 neutralized the virus in a plaque reduction assay
, confirming the identity of VP2 as the major neutralization-specific
antigen of AHSV.