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1.  Human Leukocyte Antigen (HLA) B*18 and Protection against Mother-to-Child HIV Type 1 Transmission 
Human leukocyte antigen (HLA) molecules regulate the cellular immune system and may be determinants of infant susceptibility to human immunodeficiency virus type 1 (HIV-1) infection. Molecular HLA typing for class I alleles was performed on infants followed in a Kenyan perinatal cohort. Early HIV-1 infection status was defined as infection occurring at birth or month 1, while late infection via breast milk was defined as first detection of HIV-1 after 1 month of age. Likelihood ratio tests based on a proportional hazards model adjusting for maternal CD4 T cell count and HIV-1 viral load at 32 weeks of gestation were used to test associations between infant allelic variation and incident HIV-1 infection. Among 433 infants, 76 (18%) were HIV-1 infected during 12 months of follow-up. HLA B*18 was associated with a significantly lower risk of early HIV-1 transmission [relative risk (RR) = 0.26; 95% confidence interval (CI) 0.04–0.82], and none of the 24 breastfeeding infants expressing HLA B*18 who were uninfected at month 1 acquired HIV-1 late via breast milk. We observed a trend toward increased early HIV-1 acquisition for infants presenting HLA A*29 (RR = 2.0; 95% CI 1.0–3.8) and increased late HIV-1 acquisition via breast milk for both Cw*07 and Cw*08 (RR = 4.0; 95% CI 1.0–17.8 and RR = 7.2; 95% CI 1.2–37.3, respectively). HLA B*18 may protect breast-feeding infants against both early and late HIV-1 acquisition, a finding that could have implications for the design and monitoring of HIV-1 vaccines targeting cellular immune responses against HIV-1.
PMCID: PMC3380108  PMID: 15307911
2.  Complete Genome Analysis of One of the Earliest SIVcpzPtt Strains from Gabon (SIVcpzGAB2) 
AIDS research and human retroviruses  2004;20(12):1377-1381.
Chimpanzees in west central Africa (Pan troglodytes troglodytes) are known to harbor simian immunodeficiency viruses (SIVcpzPtt) that represent the closest relatives of human immunodeficiency virus type 1 (HIV-1); however, the number of SIVcpzPtt strains that have been fully characterized is still limited. Here, we report the complete nucleotide sequence of SIVcpzGAB2, a virus originally identified in 1989 in a chimpanzee (P. t. troglodytes) from Gabon. Analysis of this sequence reveals that SIVcpzGAB2 is a member of the SIVcpzPtt group of viruses, but that it differs from other SIVcpzPtt strains by exhibiting a highly divergent Env V3 loop with an unusual crown (NLSPGTT) containing a canonical N-linked glycosylation site, an unpaired cysteine residue in Env V4, and two late (L) domain motifs (PTAP and YPSL) in Gag p6. Moreover, phylogenetic analyses indicate evidence of recombination during the early divergence of SIVcpzPtt strains; in particular, part of the pol gene sequence of SIVcpzGAB2 appears to be derived from a previously unidentified SIVcpz lineage ancestral to HIV-1 group O. These data indicate extensive diversity among naturally occurring SIVcpzPtt strains and provide new insight into the origin of HIV-1 group O.
PMCID: PMC2692896  PMID: 15650433
3.  Apoptotic and Antiapoptotic Effects of CXCR4: Is It a Matter of Intrinsic Efficacy? Implications for HIV Neuropathogenesis 
AIDS research and human retroviruses  2004;20(10):1063-1071.
CXCR4, the specific receptor for the chemokine SDF-1α that also binds CXCR4-using HIV gp120s, affects survival of different cell types, including neurons. However, current data show that the outcome of CXCR4 activation on neuronal survival may vary depending on the ligand and/or the cellular conditions. In this study, we have systematically compared the effects of SDF-1α and gp120IIIB (with or without CD4) on several intracellular pathways involved in cell survival, including MAP kinases and Akt-dependent pathways. Our data show that gp120IIIB and SDF-1α are both potent activators of MAP kinases in neuronal and non-neuronal cells, though the kinetic of these responses is slightly different. Furthermore, unlike SDF-1α, and independently of CD4, gp120IIIB is unable to stimulate Akt and some of its antiapoptotic targets (NF-κB and MDM2)—despite its ability to activate other signaling pathways in the same conditions. Finally, the viral protein is more efficient in recruiting some effectors (e.g., JNK) than others in comparison with SDF-1α (EC50 = 0.1 vs. 0.6 nM). We conclude that the intrinsic efficacy of the two ligands is significantly different and is pathway dependent. These findings have important implications for our understanding of CXCR4-mediated responses in the CNS, as well as the role of this coreceptor in HIV neuropathogenesis.
PMCID: PMC2669736  PMID: 15585097
4.  Substitution of HIV Type 1 Nef with HTLV-1 p12 
Human retroviruses, such as HTLV-1 and HIV-1, encode accessory proteins, which regulate viral pathogenesis. The p12 protein of HTLV-1 is encoded from the pX-I open reading frame, and is critical for efficient virus replication in rabbits. Although dispensable for infection, replication, and immortalization of activated lymphocytes in culture, p12 expression is important for infection of quiescent lymphocytes. Similar to HTLV-1 p12, Nef is important for virus infectivity in SIV animal models. We questioned whether p12 could replace Nef in HIV-1, and reconstitute virus replication in culture. We found that p12 could complement for effects of Nef on HIV-1 infection of Magi-CCR5 cells or macrophages.
PMCID: PMC2652723  PMID: 15585081
5.  Fine specificity and cross-clade reactivity of HIV-1 Gag-specific CD4+ T cells 
Despite growing evidence that HIV-1-specific CD4+ T helper (Th) cells may play a role in the control of viremia, discrete Th cell epitopes remain poorly defined. Furthermore, it is not known whether Th cell responses generated using vaccines based on clade B virus sequences will elicit immune responses that are effective in regions of the world where non-clade B viruses predominate. To address these issues we isolated CD4+ T cell clones from individuals with vigorous HIV-1-specific Th cell responses and identified the minimum epitopes recognized. The minimum peptide length required for induction of CD4+ T cell proliferation, IFN-γ secretion, and cytolytic activity ranged from 9 to 16 amino acids in the five epitopes studied. Cross-clade recognition of the defined epitopes was examined for variant peptides from clades A, B, C, D, and AE. Over half the variant epitopes (17 of 32) exhibited impaired recognition, defined as less than 50% of the IFN-γ secretion elicited by B clade consensus sequence. There was no evidence for antagonistic activity mediated by the variant peptides, and despite strong responses there was no escape of autologous virus from Th responses in the epitopes we studied. Abrogated recognition of variant CD4+ T cell epitopes presents a potential obstacle to vaccine development.
PMCID: PMC2553686  PMID: 15117455
6.  Unique V3 Loop Sequence Derived from the R2 Strain of HIV-Type 1 Elicits Broad Neutralizing Antibodies 
AIDS research and human retroviruses  2004;20(11):1259-1268.
DNA vaccines expressing the envelope (Env) of the human immunodeficiency virus type 1 (HIV-1) have been relatively ineffective at generating high-titer, long-lasting, neutralizing antibodies. In this study, DNA vaccines were constructed to express the gp120 subunit of Env from the isolate HIV-1R2 using both wild-type and codon-optimized gene sequences. Three copies of the murine C3d were added to the carboxyl terminus to enhance the immunogenicity of the expressed fusion protein. Mice (BALB/c) vaccinated with DNA plasmid expressing the gp120R2 using codon-optimized Env sequences elicited high-titer anti-Env antibodies regardless of conjugation to C3d. In contrast, only mice vaccinated with DNA using wild-type gp120R2 sequences fused to mC3d3, had detectable anti-Env antibodies. Interestingly, mice vaccinated with DNA expressing gp120R2 from codon-optimized sequences elicited antibodies that neutralized both homologous and heterologous HIV-1 isolates. To determine if the unique sequence found in the crown of the V3 loop of the EnvR2 was responsible for the elicitation of the cross-clade neutralizing antibodies, the codons encoding for the Pro-Met (amino acids 313–314) were introduced into the sequences encoding the gp120ADA (R5) or gp12089.6 (R5X4). Mice vaccinated with gp120ADA–mC3d3–DNA with the Pro–Met mutation had antibodies that neutralized HIV-1 infection, but not the gp12089.6–mC3d3–DNA. Therefore, the use of the unique sequences in the EnvR2 introduced into an R5 tropic envelope, in conjunction with C3d fusion, was effective at broadening the number of viruses that could be neutralized. However, the introduction of this same sequence into an R5X4-tropic envelope was ineffective in eliciting improved cross-clade neutralizing antibodies.
PMCID: PMC1550980  PMID: 15588348
7.  Auxiliary en-bloc liver-small bowel transplantation with partial pancreas preservation in pigs 
World Journal of Gastroenterology  2004;10(10):1499-1503.
AIM: The aim of this study was to describe an auxiliary combined liver-small bowel transplantation model with the preservation of duodenum, head of pancreas and hepatic biliary system in pigs. The technique, feasibility, security and immunosuppression were commented.
METHODS: Forty outbred long-white pigs were randomized into two groups, and the auxiliary composite liver/small bowel allotransplantations were undertaken in 10 long-white pigs in each group with the recipient liver preserved. Group A was not treated with immunosuppressive drugs while group B was treated with cyclosporine A and methylprednisolone after operation. The hemodynamic changes and amylase of body fluid (including blood, urine and abdominal drain) were analyzed.
RESULTS: The average survival time of the animals was 10 ± 1.929 d (6 to 25 d) in group A while more than 30 d in group B. The pigs could tolerate the hemodynamic fluctuation during operation and the hemodynamic parameters recovered to normal 2 h after blood reperfusion. The transient high amylase level was decreased to normal one week after operation and autopsy showed no pancreatitis.
CONCLUSION: Auxiliary en-bloc liver-small bowel transplantation with partial pancreas preservation is a feasible and safe model with simplified surgical techniques for composite liver/small bowel transplantation. This model may be used as a preclinical training model for clinical transplantation method, clinical liver-small bowel transplan-tation related complication research, basic research including immunosuppressive treatment, organ preservation, acute rejection, chronic rejection, immuno-tolerance and xenotransplantation.
PMCID: PMC4656292  PMID: 15133861
8.  Biochemical and radiological predictors of malignant biliary strictures 
World Journal of Gastroenterology  2004;10(10):1504-1507.
AIM: Differentiation of benign biliary strictures (BBS) from malignant biliary strictures (MBS) remains difficult despite improvement in imaging and endoscopic techniques. The aim of this study was to identify the clinical, biochemical and or radiological predictors of malignant biliary strictures.
METHODS: We retrospectively reviewed all charts of patients who had biliary strictures (BS) on endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous cholangiography (PTC) in case of unsuccessful ERCP from March 1998 to August 2002. Patient characteristics, clinical features, biochemical, radiological and biopsy results were all recorded. Stricture etiology was determined based on cytology, biopsy or clinical follow-up. A receiver operator characteristic (ROC) curve was constructed to determine the optimal laboratory diagnostic criterion threshold in predicting MBS.
RESULTS: One hundred twenty six patients with biliary strictures were enrolled, of which 72 were malignant. The mean age for BBS was 53 years compared to 62.4 years for MBS (P = 0.0006). Distal bile duct stricture was mainly due to a malignant process 48.6% vs 9% (P = 0.001). Alkaline phosphates and AST levels were more significantly elevated in MBS (P = 0.0002). ROC curve showed that a bilirubin level of 84 μmol/L or more was the most predictive of MBS with a sensitivity of 98.6%, specificity of 59.3% and a positive likelihood ratio of 2.42 (95%CI: 0.649-0.810). Proximal biliary dilatation was more frequently encountered in MBS compared to BBS, 73.8% vs 39.5% (P = 0.0001). Majority of BBS (87%) and MBS (78%) were managed endoscopically.
CONCLUSION: A serum bilirubin level of 84 μmol/L or greater is the best predictor of MBS. Older age, proximal biliary dilatation, higher levels of bilirubin, alkaline phosphatase, ALT and AST are all associated with MBS. ERCP is necessary to diagnose and treat benign and malignant biliary strictures.
PMCID: PMC4656293  PMID: 15133862

Results 1-8 (8)