Impact of amino acid substitutions in the V2 and C2 regions of human immunodeficiency virus type 1 CRF01_AE envelope glycoprotein gp120 on viral neutralization susceptibility to broadly neutralizing antibodies specific for the CD4 binding site.

Background: The CD4 binding site (CD4bs) of envelope glycoprotein (Env) gp120 is a functionally conserved, important target of anti-human immunodeficiency virus type 1 (HIV-1) neutralizing antibodies. Two neutralizing human monoclonal antibodies, IgG1 b12 (b12) and VRC01, are broadly reactive neutralizing antibodies which recognize conformational epitopes that overlap the CD4bs of Env gp120; however, many CRF01_AE viruses are resistant to neutralization mediated by these antibodies. We examined the mechanism underlying the b12 resistance of the viruses using CRF01_AE Env (AE-Env)-recombinant viruses in this study.

CRF01_AE-specific neutralizing activity observed in plasma derived from HIV-1-infected Thai patients residing in northern Thailand: comparison of neutralizing breadth and potency between plasma derived from rapid and slow progressors.

Background: Development of a protective vaccine against human immunodeficiency virus type 1 (HIV-1) is an important subject in the field of medical sciences; however, it has not yet been achieved. Potent and broadly neutralizing antibodies are found in the plasma of some HIV-1-infected patients, whereas such antibody responses have failed to be induced by currently used vaccine antigens. In order to develop effective vaccine antigens, it is important to reveal the molecular mechanism of how strong humoral immune responses are induced in infected patients.

Appearance of Drug Resistance-Associated Mutations in Human Immunodeficiency Virus Type 1 CRF01_AE Integrase Derived from Drug-Naive Thai Patients.

CRF01_AE is a major subtype of human immunodeficiency virus type 1 (HIV-1) circulating in Southeast Asia, including Thailand. We performed genotypic studies on HIV-1 CRF01_AE integrase derived from plasma samples from drug-naive Thai patients. Direct sequencing of amplified CRF01_AE integrase genes revealed that although no primary mutations associated with drug resistance to integrase inhibitors were detected, at least one secondary mutation was found in 96% of samples.

Design and evaluation of antiretroviral peptides corresponding to the C-terminal heptad repeat region (C-HR) of human immunodeficiency virus type 1 envelope glycoprotein gp41.

Two alpha-helical heptad repeats, N-HR and C-HR, located in the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp41, play an important role in membrane fusion by forming a 6-helix bundle. C34, a peptide mimicking C-HR, inhibits the formation of the 6-helix bundle; thus, it has potential as a novel antiretroviral compound. In order to improve the inhibitory effect of C34 on HIV-1 replication, we designed new C34-derived peptides based on computational analysis of the stable conformation of the 6-helix bundle.

The role of lysine residue at amino acid position 165 of human immunodeficiency virus type 1 CRF01_AE Gag in reducing viral drug susceptibility to protease inhibitors.

Recombinant human immunodeficiency virus type 1 (HIV-1) containing a CRF01_AE Gag, AE-Gag62, was significantly less susceptible to protease inhibitors (PIs) than the subtype B reference strain, NL4-3; therefore, the mechanism of how AE-Gag62 reduced viral drug susceptibility to PIs was studied in this report. The results showed that the lysine residue at amino acid position 165 (K165) of AE-Gag62 played a role in reducing the drug susceptibility of the recombinant virus to PIs. In addition, K165 potentially appears more frequently in CRF01_AE viruses than in the viruses of other major HIV-1 subtypes.

Two N-linked glycosylation sites in the V2 and C2 regions of human immunodeficiency virus type 1 CRF01_AE envelope glycoprotein gp120 regulate viral neutralization susceptibility to the human monoclonal antibody specific for the CD4 binding domain.

A recombinant human monoclonal antibody, IgG1 b12 (b12), recognizes a conformational epitope on human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein (Env) gp120 that overlaps the CD4 binding domain. Although b12 is able to broadly neutralize HIV-1 subtype B, C, and D viruses, many HIV-1 CRF01_AE viruses are resistant to b12-mediated neutralization. In this report, we examined the molecular mechanisms underlying the low neutralization susceptibility of CRF01_AE viruses to b12, using recently established CRF01_AE Env recombinant viruses.

Impact of amino acid variations in Gag and protease of HIV type 1 CRF01_AE strains on drug susceptibility of virus to protease inhibitors.

Background: Protease (PR) inhibitors (PIs) were designed against subtype B virus of human immunodeficiency virus type 1 (HIV-1), but believed to retain its activity against most of the other subtypes. CRF01_AE PR (AE-PR) contains background mutations that are presumed to alter the drug susceptibility of PR. In addition, amino acid variations found in HIV-1 Gag potentially affect the drug susceptibility or catalytic efficiency of PR.

Detection of drug resistance-associated and background mutations in human immunodeficiency virus type 1 CRF01_AE protease and reverse transcriptase derived from drug treatment-naive patients residing in central Thailand.

CRF01_AE is a major subtype of human immunodeficiency virus type 1 (HIV-1) circulating in Southeast Asia, including Thailand. We performed genotypic studies on HIV-1 CRF01_AE protease (PR) and reverse transcriptase (RT) derived from plasma samples from drug treatment-naive patients residing in central Thailand. Direct sequencing of amplified CRF01_AE PR and RT genes revealed that drug resistance-associated as well as background mutations were frequently detected in CRF01_AE PR.

Phenotypic studies on recombinant human immunodeficiency virus type 1 (HIV-1) containing CRF01_AE env gene derived from HIV-1-infected patient, residing in central Thailand.

Human immunodeficiency virus type 1 (HIV-1) env genes were cloned from blood samples of HIV-1-infected Thai patients, and 35 infectious CRF01_AE envelope glycoprotein (Env)-recombinant viruses were established. In this report, we examined the neutralization susceptibility of these viruses to human monoclonal antibodies, 2G12, IgG1 b12, 2F5 and 4E10, pooled patient plasma, coreceptor antagonists and fusion inhibitor, T-20. The neutralization susceptibility of CRF01_AE Env-recombinant viruses to 2F5, 4E10, patient plasma, coreceptor antagonists and T-20 varied, while most viruses showed low susceptibility to 2G12 and IgG1 b12.

Genotypic characterization of CRF01_AE env genes derived from human immunodeficiency virus type 1-infected patients residing in central Thailand.

CRF01_AE is a major subtype of human immunodeficiency virus type 1 (HIV-1) circulating in Southeast Asia, including Thailand. HIV-1 env genes were amplified by polymerase chain reaction from blood samples of HIV-1-infected patients residing in Thailand in 2006, and cloned into the pNL4-3-derived reporter viral construct. Generated envelope protein (Env)-recombinant virus was examined for its infectivity, and then 35 infectious CRF01_AE Env-recombinant viruses were selected.

Identification of the suppressive factors for human immunodeficiency virus type-1 replication using the siRNA mini-library directed against host cellular genes.

We performed the screening to find the novel host factors affecting human immunodeficiency virus type-1 (HIV-1) replication using the siRNA mini-library consisted with 257 siRNAs directed against cellular genes. J111 cells, a human acute monocytic leukemia cell line, were transfected with individual siRNA, followed by either infected or transfected with the HIV-1 molecular clone with luciferase reporter gene in 96-well plate format. The results showed that six siRNAs significantly enhanced the HIV-1 replication in J111 cells, indicating that the target cellular genes of those siRNAs may negatively regulate HIV-1 replication in normal cell culture condition.

The seroprevalence of human herpesvirus 8 infection in the Thai population.

The seroprevalence of human herpesvirus 8 (HHV-8) infection in the Thai population was investigated. Sera from 1,018 human immunodeficiency virus 1 (HIV-1)-negative and 436 HIV-1-positive individuals were tested for antibodies to latent and lytic HHV-8 antigens by indirect immunofluorescence assay (IFA) and an enzyme-linked immunosorbent assay (ELISA) using mixed recombinant orf HHV-8 proteins. The positive sera were further tested with recombinant HHV-8 protein expressed 293T cells by IFA.