470 A Unique Attenuating Deletion in the gp41 Cytoplasmic Domain of the HIV-1 from an Individual With Long-term Non-progressive Infection J. Haran, M. Somasundaran, J.L. Sullivan, T.C. Greenough* Univ of Massachusetts Med Sch, Worcester
Background: Viruses from individuals with long-term, non-progressive HIV-1 infection are commonly found to have uniformly persistent, unique, and difficult-to-revert polymorphisms. Sequence analysis of a virus isolated from a remarkable long-term non-progressor showed a truncation involving the last 20 amino acids of the gp41 cytoplasmic domain (CD). The gp41 CD is a highly conserved region with important roles that determine viral infectivity. We hypothesized that this polymorphism has an attenuating effect on the virus and has contributed to the unusual course of infection. To provide evidence for this, we sought to determine if this unique polymorphism 1) was uniformly present at multiple time points, and 2) has attenuating effects on viral infectivity and replication.
Methods: Additional gp41 sequences from plasma and PBMC samples obtained at multiple time points spanning 15 yrs of infection were analyzed. Site-directed mutagenesis was used to create small deletions and amino acid substitutions in the infectious molecular clone, NL4-3, to duplicate elements of this naturally occurring polymorphism. The infectivity and replication kinetics of the constructs were measured in various cell types (GHOST-CD4/X4, CEMx174, MT4, SupT1, and primary CD4 T-cells).
Results: The truncation observed in the cultured virus was present with uniform consistency in all samples from all time points tested. The NL4-3 constructs bearing elements of the polymorphism all showed reduced infectivity and a delay in replication kinetics relative to that of the parental NL4-3. The single construct that did not contain the specific amino acids present at the truncated end of the non-progressor virus had the slowest replication kinetics and infectivity.
Conclusions: The uniform presence of this gp41 CD polymorphism in the virus from this LTNP and the effects on the growth capacity of a laboratory strain suggest a contribution to the remarkable course of infection. The charge distribution in this region appeared to have effects on replication kinetics in various cell lines, suggesting that the residues found in the truncated gp41 CD of the non-progressor virus may partially compensate for the attenuating effects of this defect.
