The aim of this study was to describe and document the first case of human immunodeficiency virus type 2 (HIV-2) in the Philippines by using serological and molecular techniques and to compare the diversity of this strain to that of strains from other countries. With the introduction of HIV-2 into the country and the presence of diversified strains of HIV-1, the use of highly sensitive assays to detect all these strains is recommended

The discordant cases of seronegative, but culture and proviral HIV-2 DNA positive were found in Mumbai, India. This was corroborated by the successful isolation of HIV-2-RNA in culture medium, HIV-2 cDNA sequence determination and the detection of the antigen. The sequence of the isolated HIV-2 genomic RNA does not seem to be altered to the extent that the change will alter antibody binding. Furthermore, antibody from the same individual (even at 8 months from initial sampling) from whom HIV-2 was isolated did not react with the antigen of this strain. Those evidences imply that extremely low or non-production of the antibody may be due to suboptimal immune stimulation due to extremely slow HIV-2 replication. This low virus-load may be responsible for the negative antibody results in the HIV-2 carriers.