Maintenance of glycoprotein-determined phenotype in an HIV type 1 (pNL43) env gene-cassetting system

Enhanced replication of R5 HIV-1 isolates in vitro by a small-molecule reagent targeting HIV-1 protease

CHEMICAL ENHANCEMENT: Designed to target HIV-1 protease, a novel γ-hydroxyphosphonate has been found to significantly enhance viral replication in a panel of clinically relevant R5 HIV-1 isolates. This unexpected result constitutes the first instance of a small molecule capable of doing this, and it has implications for the preparation and use of R5 isolates in vaccine and drug development.

Neutralization activity in a geographically diverse East London cohort of human immunodeficiency virus type 1-infected patients: clade C infection results in a stronger and broader humoral immune response than clade B infection

The array of human immunodeficiency virus (HIV) subtypes encountered in East London, an area long associated with migration, is unusually heterogeneous, reflecting the diverse geographical origins of the population. In this study it was shown that viral subtypes or clades infecting a sample of HIV type 1 (HIV-1)-positive individuals in East London reflect the global pandemic. The authors studied the humoral response in 210 treatment-naïve chronically HIV-1-infected (>1 year) adult subjects against a panel of 12 viruses from six different clades. Plasmas from individuals infected with clade C, but also plasmas from clade A, and to a lesser degree clade CRF02_AG and CRF01_AE, were significantly more potent at neutralizing the tested viruses compared with plasmas from individuals infected with clade B. The difference in humoral robustness between clade C- and B-infected patients was confirmed in titration studies with an extended panel of clade B and C viruses. These results support the approach to develop an HIV-1 vaccine that includes clade C or A envelope protein (Env) immunogens for the induction of a potent neutralizing humoral response.

Sulfated beta-glucan derived from oat bran with potent anti-HIV activity

China is a major producer of oats; the annual harvested area of 350,000 ha yields approximately 465,000 tons, giving an average yield of 1.33 tons/ha. The bran is not used for animal feed as it is of poor digestibility and low nutritive content and is considered a waste byproduct. Therefore, it is advantageous to produce a value-added product from the bran. We extracted the native polysaccharide, a linear (1-3)-, (1-4)-linked beta-glucan (OBG) from the oat bran and synthesized a sulfated derivative OBGS containing 36.5% sulfate. OBGS had potent activity against a primary isolate of human immunodeficiency virus (HIV-1) in peripheral blood mononuclear cells at a concentration (EC(50)=5.98 x 10(-4) microM) approximately 15,000 times below its cytotoxic concentration. OBGS was also active postinfection (EC(50)=5.3 x 10(-4) microM) and protected pretreated peripheral mononuclear cells (EC(50)=5.2 x 10(-2) microM) washed free of the compounds prior to infection. Thus, OBGS has potential as a vaginal microbicide and is the first such report for oat bran derived sulfated beta-glucan.

Structural features and anti-HIV-1 activity of novel polysaccharides from red algae Grateloupia longifolia and Grateloupia filicina

Since sulphated polysaccharides have antiviral activity in vitro, we examined the structure and antiretroviral activity of native sulphated galactans extracted from the red algae, Grateloupia filicina (GFP) and Grateloupia longifolia (GLP). The sulphate contents of GFP and GLPE (the 1,4-alpha-d-glucan-glucanohydrolase digest of GLP) were 25.7 and 18.5%, respectively. The sulphate ester groups were located at carbon 2 for GFP and at carbon 2 and 6 for GLPE. Antiretroviral activity was investigated with a primary isolate (PI) of HIV-1 and human peripheral blood mononuclear cells (PBMCs) rather than T-cell line adapted (TCLA) HIV-1 and T-cell lines because it is more representative of the in vivo situation. Both compounds and their derivatives had potent anti-HIV-1 activity when added at the time of infection, and 2h post-infection (EC50s 0.010-0.003microM, EC(90s) 0.87-0.33microM) and low cytotoxicity. Their potential medical application as virucidal vaginal formulations is discussed.

Initial events in establishing vaginal entry and infection by human immunodeficiency virus type-1

Understanding the initial events in the establishment of vaginal human immunodeficiency virus type-1 (HIV-1) entry and infection has been hampered by the lack of appropriate experimental models. Here, we show in an ex vivo human organ culture system that upon contact in situ, HIV-1 rapidly penetrated both intraepithelial vaginal Langerhans and CD4⁺ T cells. HIV-1 entered CD4⁺ T cells almost exclusively by CD4 and CCR5 receptor-mediated direct fusion, without requiring passage from Langerhans cells, and overt productive infection ensued. By contrast, HIV-1 entered CD1a⁺ Langerhans cells primarily by endocytosis, by means of multiple receptors, and virions persisted intact within the cytoplasm for several days. Our findings shed light on the very earliest steps of mucosal HIV infection in vivo and may guide the design of effective strategies to block local transmission and prevent HIV-1 spread.

Substitution of hiv type-1 non-B env genes in C2, a subtype B cassette system, results in functional chimeric viruses

Env gene glycoprotein products are essential to viral infectivity and important targets for a host's humoral and cellular immune responses. We have reported the construction of C2, an effective env gene cassetting system for assessing biological properties of HIV-1 subtype B env gene glycoprotein products within a constant genetic background (Zheng NN and Daniels RS: AIDS Res Hum Retroviruses 2001;17:1501-7506). Here we report the ability of C2 to produce chimeric subtype A, C, D, A/E, F, and J HIV-1 and studies of the viruses' biological properties. Virus RNAs were extracted and full-length env genes rescued by RT-PCR. Expression-competent env genes were cloned into the C2 cassette and chimeric recombinant viruses produced by transfecting 293T cells. For each subtype, X4 viruses yielded higher TCID(50) than R5 viruses and the TCID(50) of chimeric viruses were either the same as or lower than their parental viruses. The limited coreceptor usage of R5-tropic parent viruses was retained in the chimeric viruses. Generally, with the exception of the subtype C virus (SE12808), the X4-tropic parental viruses utilized CXCR4 and a wide range of additional coreceptors, while their respective chimeric viruses retained CXCR4 usage but showed a more limited range in respect of other coreceptors. The replication rates of non-B subtype chimeric viruses were generally lower (1.5- to 13.6-fold) than their respective parental viruses with the exception of C2-92UG029, an X4-tropic subtype A chimeric virus. This study demonstrates that C2 is a functional cassette capable of producing infectious chimeric viruses to allow study of the biological phenotypes and functions of HIV-1 subtype B and non-B subtype glycoproteins.

An HIV type 1 subtype B founder effect in Korea: gp160 signature patterns infer circulation of CTL-escape strains at the population level

HIV-1 subtype B predominates in the Republic of Korea. Phylogenetic analyses of sequences for complete nef genes and env gene fragments encoding the V3 loop have identified a major monophyletic Korean subclade that is distinct from Western subtype B sequences in the Los Alamos HIV Sequence Database. This was investigated further by sequence analysis of complete env genes recovered from the DNA of peripheral blood mononuclear cells for matched groups of Koreans, four patients per group, previously assigned as being infected with either Korean or Western strains. The phylogenetic classifications were confirmed and analysis of the translation products identified 32 amino acid signature pattern differences, dispersed throughout gp160, which differentiate the two subclades. Twenty-three of these positions map to epitopes recognized by HLA-I-restricted cytotoxic T-lymphocytes (CTL) as catalogued in the Los Alamos HIV Immunology Database. The remaining nine map at or close to sites predicted to be targets for immunoproteasomes that are involved in producing peptides that bind to MHC Class I. These results suggest that a founder effect in the Korean population is based on the spread of CTL-escape/host-adapted HIV-1 strains.