BIOLOGICAL CHARACTERISTICS OF HIV-I STRAIN IN THE SOUTH OF VIETNAM
Truong thi
Xuan Lien*, Luong thu Tram*, Cao thu Cuc*, Prof. F. Barré Sinoussi**
* Institut
Pasteur de HCM Ville
** Institut
Pasteur de Paris:Unité de biologie des Rétrovirus.
56 HIV-I isolates were obtained from HIV-I seropositive individuals living in HoChiMinh city and six provinces in the South of Vietnam. HIV-I env sequences spanning the V3-V5 region of the gp120 coding sequence were PCR amplified and analyzed using the Heteroduplex Mobility Assay (HMA) for a rapid and reliable subtyping. Phylogenetic analyze was performed on V3 env sequences. Viruses were isolated from patient Peripheral Blood Mononuclear Cells (PBMC) in coculture with healthy donor stimulated PBMCs or with stimulated cord blood cells.
The phenotype of primary isolates was established using primary cultures on PBMCs, macrophages and MT2 cells. The activity to be neutralized by autologous and heterologous HIV I antibodies was evaluated using an infectivity assay on human PBMCs.
Results:
HIV-I
subtype E is predominant in the Southern of Vietnam. Of the 56 patient enrolled
in the study, 54 were infected by a subtype E (96%), only 2 were by a subtype
B.
The
predominance of HIV-I subtype E was found both in patients infected by sexual
contact and parental route.
Subtype
E found in
Most
of isolates have a NSI phenotype 70% (21 of 30 samples studied). 9 isolates have
SI phenotype (30%).
None
of 21 studied plasma presented autologous anti HIV-I
neutralizing antibodies but heterologous neutralizing antibodies were detected
in 7 patients.
Conclusions:
Our study clearly indicates that HIV I subtype E is predominant today in the Southern of Vietnam. Subtype E infections are identified in both the two risk group populations (intravenous drug users, prostitutes) suggesting a high rate of parental and sexual transmissibility of HIV I subtype E.Only few isolates seem to present a SI phenotype, suggesting that most infected individual are probably still in the asymptomatic phase of infection Our data on neutralization are consistent with this hypothesis.
Altogether our findings strongly support a recent introduction of HIV 1 in the Southern of Vietnam that should be useful for information and education programs.