Research Topics

 

 

One of the major research interests of the LRB is to study the biochemistry and enzymology of retroviral replication, with an emphasis on the function and features of the viral proteinase (PR).

All replication competent retroviruses code for a PR. The function of the mature PR is critical for virion replication. The HIV-1 PR has proved to be an excellent target for antiretroviral therapy of AIDS, and various PR inhibitors are now in clinical use. However, there is a rapid selection of viral variants that are resistant to inhibitors of PR. Comparative studies of various PRs have revealed the common features of their specificity. These studies are expected to aid the rational design of broad-spectrum inhibitors effective against various retroviral proteinases, including the mutant HIV-1 enzymes appearing in drug resistance. Previously we have studied and characterized the PR of the following retrovirues: HIV-1, HIV-2, equine infectious anemia virus, human T-cell leukemia virus, bovine leukemia virus, avian myeloblastosis virus, and human foamy virus. Currently we are concentrating on the characterization of mutant HIV-1 and HTLV-1 proteinases, as well as on the characterization of murine leukemia virus and mouse mammary tumor virus proteinases. Besides the detailed characterization of various retroviral PRs, we are also involved in the efforts to prove the previously suggested early-phase function of the PR

The specificity of the proteases of eleven retroviruses was studied using a series of oligopeptides having single amino acid substitutions in various positions of a naturally occurring cleavage site of HIV-1. The protease set included at least one member from each of the seven genera of the family Retroviridae.

 

An intracellularly expressed defective HIV-1 PR monomer could function as a dominant-negative inhibitor of the enzyme that requires dimerization for activity. Based on in silico studies, two mutant PRs harboring hydrophilic mutations, capable of forming favorable inter- and intrasubunit interactions, were selected. The mutant PRs showed dose-dependent inhibition of the wild-type PR in a fluorescent microtiter plate PR assay. For the first time, heterodimerization between wild-type and dominant-negative mutant PRs were demonstrated by NMR spectroscopy. In cell culture experiments, infectivity of viral particles containing PR- RER protein was reduced by 82%.

 


Members of the LRB are also involved in other collaborative works. These include studies of the homo- and heteroassociation patterns of ErbB oncogenes, and studies of shedding events leading to altered signal transductions through ErbB receptors. This collaboration is supported by a EU5 grant, and is performed through the reseach group of Dr. Janos Szollosi (Department of Biophysics, UD).

 

LRB is is also historically involved in studies on the proteolytic systems of the anterior segment of the eye, in collaboration with the team of Dr. Andras Berta (Department of Ophthalmology, UD).  Another collaboration involves characterization of potyviral proteases, in collaboration with Dr. David Waugh ( NCI- Frederick, USA). LRB has also been involved in the application of retroviral-derived vectors in gene therapy. Retroviruses are ideal tools for gene therapy, especially since their life cycle includes a highly efficient integration step.

 

 



 

 

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