Chronic Hepatitis B and C Co-Infection Increased All-Cause Mortality in HAART-Naive HIV Patients in Northern Thailand

A total of 755 highly active antiretroviral therapy (HAART)-naive HIV-infected patients were enrolled at a government hospital in Thailand from 1 June 2000 to 15 October 2002. Census date of survival was on 31 October 2004 or the date of HAART initiation. Of 700 (92.6%) patients with complete data, the prevalence of hepatitis B virus (HBV) surface antigen and anti-hepatitis C virus (HCV) antibody positivity was 11.9% and 3.3%, respectively. Eight (9.6%) HBV co-infected patients did not have anti-HBV core antibody (anti-HBcAb). During 1166.7 person-years of observation (pyo), 258 (36.9%) patients died [22.1/100 pyo, 95% confidence interval (CI) 16.7–27.8]. HBV and probably HCV co-infection was associated with a higher mortality with adjusted hazard ratios (aHRs) of 1.81 (95% CI 1.30–2.53) and 1.90 (95% CI 0.98–3.69), respectively. Interestingly, HBV co-infection without anti-HBc Ab was strongly associated with death (aHR 6.34, 95% CI 3.99–10.3). The influence of hepatitis co-infection on the natural history of HAART-naive HIV patients requires greater attention

Characterization of H5N1 influenza viruses isolated from humans in vitro

Since December 1997, highly pathogenic avian influenza A H5N1viruses have swept through poultry populations across Asian countries and been transmitted into African and European countries. We characterized 6 avian influenza H5N1 viruses isolated from humans in 2004 in Thailand. A highly pathogenic (HP) KAN353 strain showed faster replication and higher virulence in embryonated eggs compared to other strains, especially compared to the low pathogenic (LP) SP83 strain. HP KAN353 also showed strong cytopathogenicity compared to SP83 in Madin-Darby canine kidney cells. Interestingly, LP SP83 induced smaller plaques compared to other strains, especially HP KAN353. PB2 amino acid 627E may contribute to low virulence, whereas either PB2 amino acid 627 K or the combination of 627E/701N seems to be associated with high virulence. The in vitro assays used in this study may provide the basis for assessing the pathogenesis of influenza H5N1 viruses in vivo

Unique CRF01_AE Gag CTL Epitopes Associated with Lower HIV-Viral Load and Delayed Disease Progression in a Cohort of HIV-Infected Thais

Cytotoxic T Lymphocytes (CTLs) play a central role in controlling HIV-replication. Although numerous CTL epitopes have been described, most are in subtype B or C infection. Little is known about CTL responses in CRF01_AE infection. Gag CTL responses were investigated in a cohort of 137 treatment-naïve HIV-1 infected Thai patients with high CD4+ T cell counts, using gIFN Enzyme-Linked Immunospot (ELISpot) assays with 15-mer overlapping peptides (OLPs) derived from locally dominant CRF01_AE Gag sequences. 44 OLPs were recognized in 112 (81.8%) individuals. Both the breadth and magnitude of the CTL response, particularly against the p24 region, positively correlated with CD4+ T cell count and inversely correlated with HIV viral load. The breadth of OLP response was also associated with slower progression to antiretroviral therapy initiation. Statistical analysis and single peptide ELISpot assay identified at least 17 significant associations between reactive OLP and HLA in 12 OLP regions; 6 OLP-HLA associations (35.3%) were not compatible with previously reported CTL epitopes, suggesting that these contained new CTL Gag epitopes. A substantial proportion of CTL epitopes in CRF01_AE infection differ from subtype B or C. However, the pattern of protective CTL responses is similar; Gag CTL responses, particularly against p24, control viral replication and slow clinical progression

HLA-Associated Immune Pressure on Gag Protein in CRF01_AE-Infected Individuals and Its Association with Plasma Viral Load

BACKGROUND: The human leukocyte antigen (HLA)-restricted cytotoxic T-lymphocyte (CTL) immune response is one of the major factors determining the genetic diversity of human immunodeficiency virus (HIV). There are few population-based analyses of the amino acid variations associated with the host HLA type and their clinical relevance for the Asian population. Here, we identified HLA-associated polymorphisms in the HIV-1 CRF01_AE Gag protein in infected married couples, and examined the consequences of these HLA-selected mutations after transmission to HLA-unmatched recipients. METHODOLOGY/PRINCIPAL FINDINGS: One hundred sixteen HIV-1-infected couples were recruited at a government hospital in northern Thailand. The 1.7-kb gag gene was amplified and directly sequenced. We identified 56 associations between amino acid variations in Gag and HLA alleles. Of those amino acid variations, 35 (62.5%) were located within or adjacent to regions reported to be HIV-specific CTL epitopes restricted by the relevant HLA. Interestingly, a significant number of HLA-associated amino acid variations appear to be unique to the CRF01_AE-infected Thai population. Variations in the capsid protein (p24) had the strongest associations with the viral load and CD4 cell count. The mutation and reversion rates after transmission to a host with a different HLA environment varied considerably. The p24 T242N variant escape from B57/58 CTL had a significant impact on the HIV-1 viral load of CRF01_AE-infected patients. CONCLUSIONS/SIGNIFICANCE: HLA-associated amino acid mutations and the CTL selection pressures on the p24 antigen appear to have the most significant impact on HIV replication in a CRF01_AE-infected Asian population. HLA-associated mutations with a low reversion rate accumulated as a footprint in this Thai population. The novel HLA-associated mutations identified in this study encourage us to acquire more extensive information about the viral dynamics of HLA-associated amino acid polymorphisms in a given population as effective CTL vaccine targets

Molecular Evolution of HIV-1 CRF01_AE Env in Thai Patients

BACKGROUND: The envelope glycoproteins (Env), gp120 and gp41, are the most variable proteins of human immunodeficiency virus type 1 (HIV-1), and are the major targets of humoral immune responses against HIV-1. A circulating recombinant form of HIV-1, CRF01_AE, is prevalent throughout Southeast Asia; however, only limited information regarding the immunological characteristics of CRF01_AE Env is currently available. In this study, we attempted to examine the evolutionary pattern of CRF01_AE Env under the selection pressure of host immune responses. METHODOLOGY/PRINCIPAL FINDINGS: Peripheral blood samples were collected periodically over 3 years from 15 HIV-1-infected individuals residing in northern Thailand, and amplified env genes from the samples were subjected to computational analysis. The V5 region of gp120 showed highest variability in several samples over 3 years, whereas the V1/V2 and/or V4 regions of gp120 also showed high variability in many samples. In addition, the N-terminal part of the C3 region of gp120 showed highest amino acid diversity among the conserved regions of gp120. Chronological changes in the numbers of amino acid residues in gp120 variable regions and potential N-linked glycosylation (PNLG) sites are involved in increasing the variability of Env gp120. Furthermore, the C3 region contained several amino acid residues potentially under positive selection, and APOBEC3 family protein-mediated G to A mutations were frequently detected in such residues. CONCLUSIONS/SIGNIFICANCE: Several factors, including amino acid substitutions particularly in gp120 C3 and V5 regions as well as changes in the number of PNLG sites and in the length of gp120 variable regions, were revealed to be involved in the molecular evolution of CRF01_AE Env. In addition, a similar tendency was observed between CRF01_AE and subtype C Env with regard to the amino acid variation of gp120 V3 and C3 regions. These results may provide important information for understanding the immunological characteristics of CRF01_AE Env

Track A Basic Science

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138319/1/jia218438.pd

Characteristics of Clostridium difficile strains isolated from asymptomatic individuals and from diarrheal patients

AbstractObjectivesTo characterise genotypes of Clostridium difficile strains isolated from asymptomatic individuals and patients with diarrhea.MethodsFecal specimens from 235 asymptomatic infants <12 months, 76 asymptomatic children 1–11 years and 132 adult patients with antibiotic-associated and non-antibiotic-associated diarrhea obtained from Siriraj Hospital, Bangkok from October 1998 to April 1999 were examined for C. difficile by cycloserine-cefoxitin-fructose agar culture. The presence of the C. difficile toxin A gene was determined by specific PCR with the use of primers 5-(CCC AAT AGA AGATTC AAT ATT AAG CTT)-3 and 5-(GGA AGA AAA GAA CTT CTG GCT CAC TCA GGT)-3. All C. difficile isolates were subsequently genotyped by pulsed-field gel electrophoresis (PFGE).ResultsThe C. difficile strains were found in 28 (11.9%) asymptomatic infants, 16 (21.1%) asymptomatic children and 33 (25%) adult patients. In total, 14 PFGE types and eight subtypes designated as types A, B, C, D, E, F, G, H, I, J, K, L, M and N, and A1, A2, A3, A4, B1, B2, B3 and E1, respectively, were identified. Only two isolates from infants and 18 isolates from adult patients were toxin A gene positive by PCR. Both isolates of toxigenic C. difficile were from infants in the same ward and were PFGE type B. PFGE type A was the predominant type among all toxigenic isolates (12 of 18 isolates) from adult patients. The other PFGE types of toxigenic C. difficile found in adult patients were: type A1, one isolate; type B, four isolates; and type C, one isolate. Types B2 and D were identified in 38.5% and 46.2%, respectively, of the toxin A gene-negative isolates of C. difficile from infants.ConclusionsThese results revealed the occurrence of three distinct clusters from different wards in Siriraj Hospital. The toxigenic C. difficile of PFGE type A and related subtypes was a predominant infective clone in adult patients, whereas non-toxigenic C. difficile types B2 and D were encountered in asymptomatic infants. This information can be useful in epidemiologic investigations