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Alcelaphine herpesvirus–1 (AlHV-1), a causative agent of malignant catarrhal fever in cattle,
was detected in wildebeest (Connochaetes taurinus) placenta tissue for the first time. Although
viral load was low, the finding of viral DNA in over 50%of 94 samples tested lends support
to the possibility that placental tissue could play a role in disease transmission and that
wildebeest calves are infected in utero. Two viral loci were sequenced to examine variation
among virus samples obtained from wildebeest and cattle: the ORF50 gene, encoding the
lytic cycle transactivator protein, and the A9.5 gene, encoding a novel polymorphic viral glycoprotein.
ORF50 was well conserved with six newly discovered alleles differing at only one or
two base positions. In contrast, while only three new A9.5 alleles were discovered, these differed
by up to 13% at the nucleotide level and up to 20% at the amino acid level. Structural homology
searching performed with the additional A9.5 sequences determined in this study
adds power to recent analysis identifying the four-helix bundle cytokine interleukin-4 (IL4) as
themajor homologue. The majority of MCF virus samples obtained from Tanzanian cattle and
wildebeest encoded A9.5 polypeptides identical to the previously characterized A9.5 allele
present in the laboratory maintained AlHV-1 C500 strain. This supports the view that AlHV-1
C500 is suitable for the development of a vaccine for wildebeest-associated MCF. |
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