Background
HIV-1 subtype B' isolates have been predominantly circulating in China. Their intra- and inter-subtype neutralization sensitivity to autologous and heterologous plasmas has not been well studied.
Conclusions
These findings suggest that the HIV-1 subtype B' viruses may mutate under the immune pressure, thus becoming resistant to the autologous nAbs, possibly by changing the number of PNGS in the V1-V5 region of the viral gp120. Some of primary HIV-1 isolates are able to induce both intra- and inter-subtype cross-neutralizing antibody responses.
Results
Twelve HIV-1 B' clinical isolates obtained from patients were tested for their intra- and inter-subtype neutralization sensitivity to the neutralization antibodies in the plasmas from patients infected by HIV-1 B' and CRF07_BC subtypes, respectively. We found that the plasmas from the HIV-1 B'-infected patients could potently neutralize heterologous viruses of subtype B' with mean ID50 titer (1/x) of about 67, but they were not effective in neutralizing autologous viruses of subtype B' with mean ID50 titer (1/x) of about 8. The plasmas from HIV-1 CRF07_BC-infected patients exhibited weak inter-subtype neutralization activity against subtype B' viruses with ID50 titer (1/x) is about 22. The neutralization sensitivity of HIV-1 B' isolates was inversely correlated with the neutralizing activity of plasmas from HIV-1 B'-infected patients (Spearman's r = -0.657, P = 0.020), and with the number of potential N-glycosylation site (PNGS) in V1-V5 region (Spearman's r = -0.493, P = 0.034), but positively correlated with the viral load (Spearman's r = 0.629, P = 0.028). It had no correlation with the length of V1-V5 regions or the CD4+ T cell count. Virus AH259V has low intra-subtype neutralization sensitivity, it can be neutralized by 17b (IC50: 10μg/ml) and 447-52D (IC50: 1.6μg/ml), and the neutralizing antibodies (nAbs) in plasma AH259P are effective in neutralizing infection by the primary HIV-1 isolates with different subtypes with ID50 titers (1/x) in the range of 32-396. Conclusions: These findings suggest that the HIV-1 subtype B' viruses may mutate under the immune pressure, thus becoming resistant to the autologous nAbs, possibly by changing the number of PNGS in the V1-V5 region of the viral gp120. Some of primary HIV-1 isolates are able to induce both intra- and inter-subtype cross-neutralizing antibody responses.