In the geographic distribution of HIV-2, it is known that this infection is most prevalent in West Africa. Since 1986 we have studied seropositive and seronegative clusters, in Guinea-Bissau with follow-ups in 1988, 1989, 1990 and 1991. Analysis of the results show the high incidence of this infection. 8.51% of the 4,372 people of the general population studied were seropositive, showing the high predominance of HIV-2 infection. Only 4 cases were exclusively reactive to HIV-1 and a slow evolution of HIV-1 infections. In the seroconversions of HIV-2 infections the antibodies appeared first to the core components and secondly to the surface glycoproteins. Some of the laboratory parameters affected in the evolution of the infection include a gradual increase in immunoglobulins and a decrease in CD4 lymphocytes and in the CD4/CD8 ratio. A comparison of these variations in HIV-2 infected people, with or without cross-reactivity to HIV-1, reveals that they are much more evident in exclusively HIV-2 positive people. This fact can indicate that the variants responsible for the cross-reactions are less pathogenic and phylogenetically less developed.
PIP: In 1986, a total of 4372 persons were included in an HIV-2 seroepidemiological study covering the whole of Guinea-Bissau. An 8.5% incidence of HIV-2 infection was revealed by the enzyme-linked immunosorbent assay (ELISA) confirmed by Western Blot and/or RIPA. Only 4 cases of HIV-1 seropositivity were found. Annual follow-up of 78 seropositive (e died of AIDS) and 320 seronegative individuals in 1988, 1989, 1990, and 1991 was initiated. In the present investigation, a total of 70 individuals were included: 19 were seropositive (6 with double reactivity) and 51 were seronegative. During this period there were 3 seroconversion cases among seronegative persons, and the appearance of double reactivity in 3 previously HIV-2 positive cases. The reexamination of sera before seroconversion indicated reactivity to the core proteins and in 3 cases to GP-160 or GP-140 surface glycoproteins. The average values of immunoglobulins increased, but the beta-2 microglobulin, and cytomegalovirus antibodies (CMV) did not differ in the sera of 1250 decreased patients compared with seronegative persons. In seropositives, a progressive diminution of the CD4 lymphocyte values and of the T4/T8 (CD4/CD8) ratio was observed which was much more evident in HIV-2 monoreactive patients than in double reactive patients. The interpretation of HIV-1 and HIV-2 double reactivity whether the result of a double infection or of an intermediate variant of the virus between HIV-1 and HIV-2 has not been reconciled with these results. These findings indicate that the variants responsible for double reactivity are less pathogenic, less adapted to the human host, and less developed phylogenetically.