Tat protein vaccination of cynomolgus macaques influences SHIV-89.6P cy243 epitope variability.
In a previous study we showed that vaccination with the native Tat protein controlled virus replication in five out of seven monkeys against challenge with the simian human immunodeficiency virus (SHIV)-89.6P cy243 and that this protection correlated with T helper (Th)-1 response and cytotoxic T lymphocyte (CTL) activity. To address the evolution of the SHIV-89.6P cy243 both in control and vaccinated infected monkeys, the sequence of the human immunodeficiency virus (HIV)-1 Tat protein and the C2-V3 Env region of the proviral-DNA-derived clones were analyzed in both control and vaccinated but unprotected animals. We also performed analysis of the T cell epitope using a predictive epitope model taking into consideration the phylogeny of the variants. Our results suggest that even though the viral evolution observed in both groups of monkeys was directed toward variations in the major histocompatibility complex (MHC)-I epitopes, in the control animals it was associated with mutational escape of such epitopes. On the contrary, it is possible that viral evolution in the vaccinated monkeys was linked to mutations that arose to keep high the viral fitness. In the vaccinated animals the reduction of epitope variability, obtained prompting the immune system by vaccination and inducing a specific immunological response against virus, was able to reduce the emergence of escape mutants. Thus the intervention of host's selective forces in driving CTL escape mutants and in modulating viral fitness appeared to be different in the two groups of monkeys. We concluded that in the vaccinated unprotected animals, vaccination with the Tat protein induced a broad antiviral response, as demonstrated by the reduced ability to develop escape mutants, which is known to help in the control of viral replication.
National AIDS Center, Istituto Superiore di Sanità, V.le Regina Elena 299, 00161 Rome, Italy.
Barbara
B
Ridolfi
Domenico
D
Genovese
Claudio
C
Argentini
Maria Teresa
MT
Maggiorella
Leonardo
L
Sernicola
Stefano
S
Buttò
Fausto
F
Titti
Alessandra
A
Borsetti
Barbara
B
Ensoli
D016915:AIDS Vaccines / Q000276:immunology*; D000163:Acquired Immunodeficiency Syndrome / Q000276:immunology* / Q000517:prevention & control / Q000821:virology; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D000939:Epitopes / Q000276:immunology*; D015696:Gene Products, tat / Q000235:genetics / Q000276:immunology*; D006678:HIV / Q000235:genetics / Q000276:immunology*; D015483:HIV Antibodies / Q000276:immunology; D006801:Humans; D007371:Interferon-gamma / Q000276:immunology / Q000378:metabolism; D008251:Macaca; D008252:Macaca fascicularis; D010802:Phylogeny; D018449:SAIDS Vaccines / Q000276:immunology; D016415:Sequence Alignment; D016097:Simian Acquired Immunodeficiency Syndrome / Q000276:immunology / Q000517:prevention & control / Q000821:virology; D015302:Simian Immunodeficiency Virus / Q000235:genetics / Q000276:immunology*; D013601:T-Lymphocytes / Q000276:immunology; D014779:Virus Replication
D016915:AIDS Vaccines; D000939:Epitopes; D015696:Gene Products, tat; D015483:HIV Antibodies; D018449:SAIDS Vaccines; D007371:Interferon-gamma