Session 36Poster Presentations Accessory Genes Session Day and Time: Tuesday 1:30 - 3:30 pm Room: Hall D
200 HIV-1 Vif can Substitute Functionally for SIV Vif Replication in Human But Not in Rhesus Monkey Cells S. Kar*, L. Alexander Yale Univ, New Haven, CT
Background: Primate lentivirus Vif often functions in a species-specific manner. We investigated if this specificity applied to HIV-1 Vif functionality in rhesus monkey cells.
Methods: We constructed 2 SIV recombinants, which contained the HIV-1 Vif gene, and from which the SIV Vif gene was deleted. In one recombinant (SHIV/Vif), the HIV-1 Vif sequences were inserted into the locus usually occupied by SIV Vif. In the other recombinant (SHIV/-Nef/Vif), HIV-1 Vif sequences were inserted into the locus usually occupied by SIV Nef, which is deleted in this recombinant. These recombinant DNAs were introduced into CEMx174 cells to produce viral stocks, which were titered by p27Gag ELISA. Stock virus was used to infect either CEMx174 (human) or 221 (rhesus monkey) cells, and the efficiency of replication was assessed by antigen capture.
Results: Transfection of CEMx174 cells with SHIV/Vif DNA failed to produce detectable levels of p27Gag in culture supernatants. Conversely, transfection of CEMx174 cells with SHIV/-Nef/Vif DNA resulted in high levels of virus antigen release. Furthermore, the resulting SHIV/-Nef/Vif stock replicated very similarly to wild-type SIVmac239 in human CEMx174 cells. However, infection of the rhesus monkey T-cell line 221 with SHIV/-Nef/Vif produced only transient release of relatively low levels of p27Gag. These Gag-containing culture supernatants were incubated with CEMx174 or 221 cells, which did not produce detectable levels of virus antigen release, indicating that the SHIV/-Nef/Vif viral particles produced in monkey cells were defective.
Conclusions: The efficient replication of SHIV/-Nef/Vif in human cells indicated that HIV-1 Vif interacted with SIV cis-acting elements required for virus production. However, the observed production of defective SHIV/-Nef/Vif particles in monkey cell cultures indicated that HIV-1 Vif did not interact with an essential monkey-specific factor(s). The observation of transient release of p27Ga g from the infected 221 cells suggests that the block in the production of infectious virus particles took place late in the virus replication cycle. These data suggest that the inability of HIV-1 to replicate in rhesus monkeys is, at least in part, Vif determined. Furthermore, our observations suggest a recombinant primate lentivirus containing foreign Vif sequences could produce a transient infection in a human or monkey and thus, could form the basis of a novel vaccine candidate.
