15th International AIDS Conference Bangkok, Thailand - July 11-16, 2004

Int Conf AIDS 2004 Jul 11-16; 15:(abstract no. A10115)

Aravindhan V, Gautham N, Prasad V, Narayanan PR, Narayanan S
Tuberculosis Research Centre (ICMR), Chennai, India

BACKGROUND: AIDS vaccine is a global emergency. Intense efforts are under way to identify protective epitopes and novel delivery vehicles. Grafting an epitope from an immune unfriendly environment to an immune friendly environment forms the basic of 'epitope grafting'. In this respect the present project aims at constructing an 'epitope trap vector' using Mycobacterium tuberculosis chaperonin-10 (Cpn10) antigen as a carrier antigen. The HIV-1 PND was selected as a test epitope.

METHODS AND RESULTS:: As a first step, the crystal structure of Cpn10 was analysed using INSIGHT II software, which helped identify an extended loop region for grafting the PND epitope. After cloning the Cpn10 gene, a mutant cassette was constructed, where the loop region was replaced with a 'BsmBI-AscI-BsmBI' restriction site cassette. This construct was then used to construct two versions of the Cpn-PND chimeric antigens: 1. The replacement chimera where the PND epitope replaces the Cpn10 loop 2. The insertion chimera where the PND epitope is inserted into the Cpn10 loop These chimeric genes were sub cloned into mycobacterial shuttle vectors. The expression of these constructs was checked in M. smegmatis. Experiments are underway to express these constructs in BCG. The immunogenicity of the resulting rBCG strains would be evaluated in a murine model.

CONCLUSION: Heat shock protein based epitode delivery vehicles offer novel avenues in AIDS vaccine research.

040711
A10115

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