The vaccinia virus A14.5L gene encodes a hydrophobic 53-amino-acid virion membrane protein that enhances virulence in mice and is conserved among vertebrate poxviruses
T. Betakova et al., The vaccinia virus A14.5L gene encodes a hydrophobic 53-amino-acid virion membrane protein that enhances virulence in mice and is conserved among vertebrate poxviruses, J VIROLOGY, 74(9), 2000, pp. 4085-4092
A short sequence, located between the A14L and A15L open reading frames (OR
Fs) of vaccinia virus, was predicted to encode a hydrophobic protein of 53
amino acids that is conserved in orthopoxviruses, leporipoxviruses, yatapox
iruses, and molluscipoxviruses, We constructed a recombinant vaccinia virus
with a 10-codon epitope tag appended to the C terminus of the A14.5L ORF,
Synthesis of the tagged protein occurred at late times and was blocked by a
n inhibitor of DNA replication, consistent with regulation by a predicted l
ate promoter just upstream of the A14.5L ORF, Hydrophobicity of the protein
was demonstrated by extraction into the detergent phase of Triton X-114. T
he protein was associated with purified vaccinia virus particles and with m
embranes of immature and mature virions that were visualized by electron mi
croscopy of infected cells. Efficient release of the protein from purified
virions occurred after treatment with a nonionic detergent and reducing age
nt. A mutant virus, in which the A14.5L ORF was largely deleted, produced n
ormal-size plaques in several cell lines, and the yields of infectious intr
a- and extracellular viruses were similar to those of the parent. In contra
st, with a mouse model, mutant viruses with the A14.5L ORF largely deleted
were attenuated relative to that of the parental virus or a mutant virus wi
th a restored A14.5L gene.