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J. Virol., May 1997, 3397-3406, Vol 71, No. 5
M Laughrea, L Jette, J Mak, L Kleiman, C Liang and MA Wainberg
A stem-loop termed the kissing-loop hairpin is one of the most highly
conserved structures within the leader of human immunodeficiency virus type
1 (HIV-1) and chimpanzee immunodeficiency virus genomic RNA. Because it
plays a key role in the in vitro dimerization of short HIV-1 RNA
transcripts (M. Laughrea and L. Jette, Biochemistry 35:1589-1598, 1996, and
references therein; M. Laughrea and L. Jette, Biochemistry 35:9366-9374,
1996, and references therein) and because dimeric RNAs may be preferably
encapsidated into the HIV-1 virus, alterations of the kissing-loop hairpin
might affect the in vivo dimerization and encapsidation processes.
Accordingly, substitution and deletion mutations were introduced into the
kissing-loop hairpin of an infectious HIV-1 molecular clone in order to
produce viruses by transfection methods. The infectivity of the resulting
viruses was decreased by at least 99%, the amount of genomic RNA packaged
per virus was decreased by 50 to 75%, and the proportion of dimeric genomic
RNA was reduced from >80 to 40 to 50%, but the dissociation temperature
of the genomic RNA was unchanged. There is evidence suggesting that the
deletion mutations moderately inhibited CAp24 production but had no
significant effect on RNA splicing. These results are consistent with the
kissing-loop model of HIV-1 RNA dimerization. In fact, because
intracellular viral RNAs are probably more concentrated in transfected
cells than in cells infected by one virus and because the dimerization and
encapsidation processes are concentration dependent, it is likely that much
larger dimerization and encapsidation defects would have been manifested
within cells infected by no more than one virus.
Copyright © 1997, American Society for Microbiology
Mutations in the kissing-loop hairpin of human immunodeficiency virus type 1 reduce viral infectivity as well as genomic RNA packaging and dimerization
McGill AIDS Centre, Lady Davis Institute for Medical Research, Sir Mortimer B. Davis-Jewish General Hospital, Montreal, Quebec, Canada.
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