THE FIRST EVIDENCE OF PSEUDOTYPE PRODUCTION IN A IN VITRO SUPERINFECTION SYSTEM WITH TWO DIFFERENT HIV-1 STRAINS

P. N. FERNÁNDEZ LARROSA; A. CEBALLOS; R.D. RABINOVICH; S. MARQUINA; L. A. MARTÍNEZ PERALTA

Buenos Aires, Argentina

Conferencia; 1st IAS Conference on HIV pathogenesis and treatment; 2001

Superinfection with HIV-1 occurs in vitro and in vivo and is considered to be the main cause of the high frequency of circulating recombinant forms worldwide. Besides, viral production is normally high in patients and different viral variants accumulate over the time causing the necessary conditions for superinfection. However, there is no evidence of pseudotype production with different HIV-1 strains. In order to evaluate the production of pseudotypes due to superinfection, H9-HTLVIIIB cells, infected with HXB2 viral strain, were pretreated with 2,2 ug/ml polybrene for 30 minutes at 37_C and centrifugated at 4_C, before superinfecting with MN strain (moi=1). The virus produced by the superinfected cells was used to infect MT2 cells as a revelator system of syncitia production, after been challenged by neutralization using monoclonal antibodies against HXB2 or MN. Further, the characterization of proviral DNA in MT2 cells with syncitia production was made by amplification of the C2V3 region of env gene followed by digestion with an enzime (BsmA I) that differentiates both viral strains. Virus produced by superinfected cells at days 2 to 7 was not neutralized by either antibodies. Proviral DNA from MT2 cells showing syncitia was characterized as HXB2 genome. The viral progeny of these cells was completely neutralized by antibody against HXB2 strain. These results show the production of pseudotypes consisting of HXB2 genome and envelope proteins of MN strain. However, the opposite pseudotype was not observed. Superinfection with the viral strains used induce pseudotypes production. in vivo, this viral mechanism could allow immune escape, playing an important role in the HIV persistence.