There is no Difference Between Sequences of HIV-1 Infected Patients with Stable Clinical Status and HIV-1 Reference Sequence.

BACKGROUND: The rate of human immunodeficiency virus type 1 (HIV-1) infection in Iran has increased dramatically in the past few years. HIV-1 genome sequences are pivotal for large-scale studies of inter- and intra-host evolution. To understand the molecular difference between reference HIV-1 isolate and two HIV-1 infected patients in Iran, we conducted this study to analyze some genome segments of Iranian HIV-1 isolates. METHODS: Two HIV-1-infected individuals who were under antiretroviral therapy (ARV) for 8 years with stable clinical status were enrolled. The patient's plasma samples were used for the Gag-Pol genome sequences (4500 nt). The phylogenetic tree and similarity plotty were obtained based on Gag-Pol sequences. RESULTS: Both HIV-1-infected isolates belonged to CRF35_AD subtype even though one of them had drug resistance. The HIV genome and protein sequences showed no clear difference between genome and protein sequences of our samples and the reference sequence. CONCLUSIONS: Our patient's stable clinical status had no connection to genome sequence; which could be owing to immunological factors or other patient's mode which are still unknown.

The matrix protein of HIV-1 is not sufficient for assembly and release of virus-like particles.

The matrix (MA) proteins of human immunodeficiency virus type 1 (HIV-1) and simian immunodeficiency virus (SIV) are known to be important for the targeting and assembly of lentiviral proteins. The objective of the present study was to determine whether the MA protein of HIV-1 was sufficient for particle assembly and release. Eukaryotic expression of wild-type HIV-1 Gag-Pol, HIV-1 MA alone, or SIV MA alone was analyzed with radio-immunoprecipitation, density centrifugation, and a protease protection assay. Cells that expressed HIV-1 Gag-Pol or SIV MA alone released virus-like particles (VLPs) with sucrose gradient densities of 1.15 or 1.12 g/ml, respectively. The MA and/or capsid proteins in these particles were protected from protease degradation, indicating the presence of a protective outer membrane. Expression of HIV-1 MA protein alone resulted in release of MA which pelleted through a 20% sucrose cushion but failed to enter a 20-60% sucrose gradient and was not protected from protease degradation. The MA protein of SIV was previously reported to be sufficient for production of VLPs (S. A. Gonzalez, H, K, Affrachino, H. R. Gelderblom, and A. Burney. Virology 194, 548-556, 1993; V. Liska, D. Spehner, M. Mehtali, D. Schmitt, A. Kirn, and A. M. Aubertin. J. Gen. Virol. 75, 2955-2962, 1994). Our study confirmed that result, but indicated that the MA protein of HIV-1 was not sufficient to assemble and release VLPs.

The Gag-Pol encoded proteinase of an avian retrovirus expressed in E. coli can produce a novel proteinase (PR + IleGly) that is two amino acids larger at its carboxy-terminal region than the major Gag proteinase (PR).

Gag-Pol frameshift translational products of avian retroviruses (e.g., myeloblastosis associated virus, MAV) contain a putative proteinase species of 131 amino acids that maps between the NC/PR and the PR/RT processing sites. Expression in Escherichia coli of an in-frame PR precursor that contains the natural NC/PR processing site and is translationally terminated at the PR/RT site leads to formation of a Gag-Pol proteinase of the expected molecular size (131 amino acids) and a novel PR product of 126 amino acids. This product extends 2 amino acids downstream of the gag-encoded 124 amino acids, and its proteolytic cleavage is promoted by conditions favorable for enzyme catalysis, is blocked by a specific MAV proteinase inhibitor, and can be demonstrated also for corresponding peptide substrates. The new self-processing cleavage product is termed PR(+IleGly) and exhibits similar, but slower, catalytic parameters than those of the Gag PR.