Epidemiological studies revealed that in Argentina, early predominance of B subtype has been overshadowed by the emergence of BF recombinants. Until correlates of protection are well understood, existence and determiants of cross-clade immune responses sh

G TURK; MM GHERARDI; N LAUFER; P CAHN; J COX; H SALOMON

Amsterdam, The Netherlands

Congreso; AIDS VACCINE 06 – Fifth International Conference; 2006

International Society for Antiviral Research

Objective: To characterize HIV-1 Nef-specific T cell responses in patients infected with clade B or BF URFs and to determine the degree of cross-reactivity.To characterize HIV-1 Nef-specific T cell responses in patients infected with clade B or BF URFs and to determine the degree of cross-reactivity. Methods: Fourteen HIV-1 recently infected patients (documented seroconvertion within 6 months) were enrolled. Plasma viral load, viral subtype, CD4 count, CD8 count and HLA haplotype were determined. T cell responses were assessed in an Interferon-ã (IFN-g) based ELISPOT assay using overlapping peptides arrayed in a matrix system. Positive responses were further Confirmed at the single peptide level. Statistical analysis was performed based on Spearman rank correlation, Wilcoxon or Mann-Whitney tests.Fourteen HIV-1 recently infected patients (documented seroconvertion within 6 months) were enrolled. Plasma viral load, viral subtype, CD4 count, CD8 count and HLA haplotype were determined. T cell responses were assessed in an Interferon-ã (IFN-g) based ELISPOT assay using overlapping peptides arrayed in a matrix system. Positive responses were further Confirmed at the single peptide level. Statistical analysis was performed based on Spearman rank correlation, Wilcoxon or Mann-Whitney tests. Results: Subtyping of nef gene was used to group patients. Eight out of 14 patients were Nef-B while 6 were Nef-F. Strong correlations in IFN-g T cell responses were observed in both patient groups for Nef-B and Nef-F peptide pools (0.548 for B patients and 0.771 for F patients). Neither inter or intra-clade statistical differences were observed for total anti-Nef-B or –F responses. However, responses in F patients were narrower than in B patients’ (and concentrated in the core domain of the protein) but higher in magnitude. Surprisingly, overall entropy of BF sequences was lower than in B sequences. Number of recognized peptides in B patients ranged from 1 to 6 (mean=2.75) for autologous peptides and 0 to 4 (mean=2) for heterologous peptides. In F patients, positive responses ranged from 4 to 1 for autologous and heterologous peptides (means=1.83 and 1.5, respectively). As regards magnitude of response, medians found in B patients were 179 spot forming units (SFU)/106PBMC (range 50–771) and 112.5 (50–960) for autologous and heterologous peptides, respectively. For BF infected patients, medians obtained were 776 SFU/106PBMC (range 80–4530) and 1326 (40–4250) for autologous and heterologous peptides, respectively.Subtyping of nef gene was used to group patients. Eight out of 14 patients were Nef-B while 6 were Nef-F. Strong correlations in IFN-g T cell responses were observed in both patient groups for Nef-B and Nef-F peptide pools (0.548 for B patients and 0.771 for F patients). Neither inter or intra-clade statistical differences were observed for total anti-Nef-B or –F responses. However, responses in F patients were narrower than in B patients’ (and concentrated in the core domain of the protein) but higher in magnitude. Surprisingly, overall entropy of BF sequences was lower than in B sequences. Number of recognized peptides in B patients ranged from 1 to 6 (mean=2.75) for autologous peptides and 0 to 4 (mean=2) for heterologous peptides. In F patients, positive responses ranged from 4 to 1 for autologous and heterologous peptides (means=1.83 and 1.5, respectively). As regards magnitude of response, medians found in B patients were 179 spot forming units (SFU)/106PBMC (range 50–771) and 112.5 (50–960) for autologous and heterologous peptides, respectively. For BF infected patients, medians obtained were 776 SFU/106PBMC (range 80–4530) and 1326 (40–4250) for autologous and heterologous peptides, respectively. Conclusions: Overall cross-clade T cell responses were found between patients infected with different clades. Evaluation of responses at the single peptide level allowed us to determine the existence of inter-clade differences at the frequency of epitopes recognized, structural domains targeted and magnitude of response.Overall cross-clade T cell responses were found between patients infected with different clades. Evaluation of responses at the single peptide level allowed us to determine the existence of inter-clade differences at the frequency of epitopes recognized, structural domains targeted and magnitude of response.