AEGiS-11IAC: The importance of conserved proline residues in the capsid protein of HIV-1 regarding maturation and infectivity of HIV-particles.

11th International AIDS Conference

Vancouver, British Columbia — July 7-12, 1996

The importance of conserved proline residues in the capsid protein of HIV-1 regarding maturation and infectivity of HIV-particles.

Int Conf AIDS 1996 Jul 7-12; 11:6 (abstract no. We.A.154)
Fitzon T; Universitat Regensburg, Regensburg, Germany. Fax: 49-941-944-6402. E-mail: Tanja.Fitzon@klinik.uni-regensburg.de.

OBJECTIVE: To analyze the influence of proper folding of Pr55gag on HIV- assembly and infectivity.

METHODS: Proline residues are assumed to play a key role in determining the structure of the polypeptide backbone. In the N-terminal region of p24 we substituted residues P133; P149; P166; P170; P217; P222; P225; P231 for alanin residues and leucine residues, respectively. Recombinant provirus constructs were transfected in VOS-7 cells to determine a possible influence of the sequence alterations as the virus assembly. Further analysis of the obtained transfection supernatants on CD4 positive MT4 cells gave first insight in the infectivity and early steps in virus replication of recombinant viruses.

RESULTS: The production of mature virus particles was reduced drastically (50%) in the case of P133A/L and P149A/L. The effect was even more pronounced (75-100%) in positions 166, 217 and 231. By contrast, all other substitutions had no measurable effect on correct virus assembly. Following infection of CD4 positive MT4 lymphocytes with the transfection supernatants of COS-7 cells virus phenotype had different properties compared to the wildtype. For example P222A/L showed no effect on particle release but a complete loss of its infectivity. Recently it has been shown that p24 contains the binding site for the cellular chaperon cyclophilin. Applying an in vitro binding assay we were able to corroborate a key role of P222 in chaperone binding. Obviously this mechanism is important for the early states of replication.

CONCLUSIONS: Although same Proline substitutions did not impair virus assembly, the released virus particles either exhibited a reduced replicative capacity or were completely non infectious. The molecular events, during early life cycle, that are impaired by in proper folding of p24 is under current investigation.

Keywords: AEGIS, HIV-1, Capsid, Virus Assembly, Virus Replication, Proline, Proviruses, Virion, Antigens, CD4, Peptidylprolyl Isomerase, Peptides, Binding Sites, Antiviral Agents, In Vitro, pathogenicity, virology, ICA11

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