A single amino acid substitution of the human immunodeficiency virus type 1 capsid protein affects viral sensitivity to TRIM5 alpha.
BACKGROUND
Human immunodeficiency virus type 1 (HIV-1) productively infects only humans and chimpanzees but not Old World monkeys, such as rhesus and cynomolgus (CM) monkeys. To establish a monkey model of HIV-1/AIDS, several HIV-1 derivatives have been constructed. We previously reported that efficient replication of HIV-1 in CM cells was achieved after we replaced the loop between alpha-helices 6 and 7 (L6/7) of the capsid protein (CA) with that of SIVmac239 in addition to the loop between alpha-helices 4 and 5 (L4/5) and vif. This virus (NL-4/5S6/7SvifS) was supposed to escape from host restriction factors cyclophilin A, CM TRIM5 alpha, and APOBEC3G. However, the replicative capability of NL-4/5S6/7SvifS in human cells was severely impaired.


RESULTS
By long-term cultivation of human CEMss cells infected with NL-4/5S6/7SvifS, we succeeded in rescuing the impaired replicative capability of the virus in human cells. Sequence analysis of the CA region of the adapted virus revealed a G-to-E substitution at the 116 th position of the CA (G116E). Introduction of this substitution into the molecular DNA clone of NL-4/5S6/7SvifS indeed improved the virus' replicative capability in human cells. Although the G116E substitution occurred during long-term cultivation of human cells infected with NL-4/5S6/7SvifS, the viruses with G116E unexpectedly became resistant to CM, but not human TRIM5 alpha-mediated restriction. The 3-D model showed that position 116 is located in the 6th helix near L4/5 and L6/7 and is apparently exposed to the protein surface. The amino acid substitution at the 116 th position caused a change in the structure of the protein surface because of the replacement of G (which has no side chain) with E (which has a long negatively charged side chain).


CONCLUSIONS
We succeeded in rescuing the impaired replicative capability of NL-4/5S6/7SvifS and report a mutation that improved the replicative capability of the virus. Unexpectedly, HIV-1 with this mutation became resistant to CM TRIM5 alpha-mediated restriction.
Kuroishi
Ayumu
A
Department of Viral Infections, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan.
Bozek
Katarzyna
K
Shioda
Tatsuo
T
Nakayama
Emi E
EE
D019943:Amino Acid Substitution / Q000235:genetics*; D000818:Animals; D000090103:Antiviral Restriction Factors; D002352:Carrier Proteins / Q000276:immunology* / Q000378:metabolism; D018929:Cell Culture Techniques; D002460:Cell Line; D004252:DNA Mutational Analysis; D016655:HIV Core Protein p24 / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D015497:HIV-1 / Q000235:genetics* / Q000276:immunology*; D006801:Humans; D008252:Macaca fascicularis; D008958:Models, Molecular; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000276:immunology* / Q000378:metabolism; D013601:T-Lymphocytes / Q000821:virology; D000070584:Tripartite Motif Proteins; D044767:Ubiquitin-Protein Ligases
D000090103:Antiviral Restriction Factors; D002352:Carrier Proteins; D016655:HIV Core Protein p24; D011506:Proteins; D000070584:Tripartite Motif Proteins; C514799:p24 protein, Human Immunodeficiency Virus Type 1; C477346:TRIM5 protein, human; C482587:TRIM5(alpha) protein, rhesus monkey; D044767:Ubiquitin-Protein Ligases