Figure 2

Immunofluorescence assay to detect the susceptibilities of NP-2/CD4/coreceptor cells and infection dynamics of HIV-2 and SIV through different coreceptors. a) NP-2/CD4/coreceptor cells were seeded and next day inoculated with primary isolates, HIV-2MIR and SIVsmE660. Cells were passaged in 3–4 day intervals and continued for four weeks for HIV-2 and eight weeks for SIV. Viral antigens in infected cells were determined by IFA, for which cells were smeared onto glass slides in duplicate, dried, fixed with acetone and stained with pooled human/monkey anti-HIV/SIV sera for HIV-2MIR- and SIVsmE660-antigen, respectively. Fluorescein isothiocyanate (FITC)-conjugated goat anti-human and anti-monkey IgG were used as secondary antibodies. Specific days after inoculation on infected cells were shown accordingly. b) Mean percentages of the antigen-positive cells in the two independent infection assay was calculated using IBM SPSS statistics data editor. HIV-2MIR started progressive replication via CKR-L3 and CCR6; less than 10% cells became infected within the first week after inoculation and gradually more than 80% cells became antigen-positive at day-16 and day-25 after inoculation, respectively. c) SIVsmE660 started slow infection and took more adaptation time using CKR-L3 and CCR6 as coreceptors. The virus infected less than 10% of cells with in the first four weeks of inoculation via either of the coreceptors, however, showed progressive infection to make more than 80% cells become antigen-positive at six weeks via CKR-L3 and almost eight weeks via CCR6.