Molecular genotyping of HIV-1 in 61 patients with AIDS from Lom�, Togo

Molecular epidemiology of HIV in Ghana: Dominance of CRF02_AG

Recent studies showed the importance of CRF02_AG in West Africa, although the clinical relevance of these recombinant forms of HIV remains unknown. The present study aimed at determining the molecular diversity of HIV in Ghana and investigating the possible epidemiologic advantage of recombinant HIV-1. Plasma samples collected in 1999-2002 from two populations of HIV infected individuals (144 asymptomatic candidate blood donors and 169 AIDS patients) were studied and 249 of them were molecularly characterised in gag, pol, and env regions. Five molecular groups were identified: strains clustering with CRF02_AG in all regions (147/249 or 59%), recombinant strains clustering with CRF02_AG in one or two regions (50/249 or 20%), other subtypes, pure or recombinant, but not involving CRF02_AG (37/249 or 15%), HIV-2 (11/249 or 4.5%), and double infections (4/249 or 1.5%). There was no significant difference in the distribution of HIV-1 recombinant strains according to clinical presentation. No evidence of a significant increase in CRF02_AG prevalence between 1999 and 2002 was found. Irrespective of clinical condition, CRF02_AG is the predominant molecular form of HIV-1 in Kumasi, Ghana.

The risk of hepatitis B virus infection by transfusion in Kumasi, Ghana

The risk of hepatitis B virus (HBV) transmission by transfusion in sub-Saharan Africa is considered to be relatively low, and testing of blood donors is often not done or is done relatively poorly. To re-examine this attitude, we identified HBV chronically infected blood donors from a major hospital in Ghana with a range of hepatitis B surface antigen (HBsAg) assays. Test efficacy was estimated using HBV DNA as a gold standard, and the risk of HBV infection in blood recipients was estimated for different testing strategies. Particle agglutination, dipstick, and enzyme immunoassay (EIA) HBsAg screening detected 54%, 71%, and 97% of HBV infectious donors, respectively. The risk of HBV transmission to recipients less than 10 years old ranged between 1:11 and 1:326 with blood unscreened and screened by EIA, respectively. For older recipients, the risk decreased a further 4-fold because of the high frequency of natural exposure to HBV. A total of 98% of HBsAg-confirmed positive samples contained HBV DNA. HBV DNA load was less than 1 x 10(4) IU/mL in 75% of HBsAg-reactive samples, most of them anti-HBe reactive. Approximately 0.5% of HBsAg-negative but anti-HBc-positive samples contained HBV DNA. The use of sensitive HBsAg tests is critical to prevent transfusion transmission of HBV infection to young children in a population with a 15% prevalence of chronic HBV infection in blood donors. However, this will not have much effect on the prevalence of this infection unless other strategies to protect children from infection are also advanced in parallel.

Evaluation of a transcription-mediated amplification-based HCV and HIV-1 RNA duplex assay for screening individual blood donations: a comparison with a minipool testing system

BACKGROUND

NAT was introduced for HCV RNA in 1999 to screen blood donations and improve the safety of the blood supply.

STUDY DESIGN AND METHODS

The performance of a NAT multiplex for HCV and HIV-1 RNA based on transcription-mediated amplification (TMA) was assessed with various sensitivity panels and by screening 50,000 serologically unscreened, first-time donor plasma samples. Results were compared with a routine NAT screening for HCV RNA by RT-PCR in pools of 96 plasma samples.

RESULTS

The TMA multiplex 95 percent sensitivity ranged between 22 and 54 IU per mL for HIV-1 and 15 and 20 IU per mL for HCV RNA. The rate of test failure was 8.6 percent but decreased to 4.7 percent when results of two critical periods of equipment malfunction were excluded. Test failure was related to human error, minute control contamination, and insufficient mixing of reagents at the extraction stage. All 31 repeatedly reactive samples (0.06%) were seropositive for HCV (29) or HIV-1 (2) and contained RNA detectable by discriminatory TMA and confirmatory RT-PCR, indicating 100 percent specificity. A direct comparison of TMA in individual samples and RT-PCR in plasma pools was possible on 27 HCV RNA-containing samples. Twenty-six samples were detected in plasma pools; the lack of detection of 1 sample was due to an identification error at the pooling stage.

CONCLUSION

The HCV and HIV-1 multiplex NAT had high specificity and sensitivity.

Production and characterization of monoclonal antibodies specific for a conserved epitope within hepatitis C virus hypervariable region 1

Frequent mutations in hypervariable region 1 (HVR1) of the main envelope protein of hepatitis C virus (HCV) is a major mechanism of persistence by escaping the host immune recognition. HVR1 contains an epitope eliciting neutralizing antibodies. This study was aimed to prepare broadly cross-reacting, high-affinity, monoclonal antibodies (MAb) to the HVR1 C terminus of HCV with potential therapeutic neutralizing capacity. A conserved amino residue group of glycine (G) at position 23 and glutamic acid (Q) at position 26 in HVR1 was confirmed as a key epitope against which two MAbs were selected and characterized. MAbs 2P24 and 15H4 were immunoglobulin G1 kappa chain [IgG1(kappa)], cross-reacted with 32 and 30 of 39 random C-terminal HVR1 peptides, respectively, and did not react with other HCV peptides. The V(H) of 2P24 and 15H4 heavy chains originated from Igh germ line v gene family 1 and 8, respectively. In contrast, the V(L) kappa sequences were highly homologous. The affinity (K(d)) of 2P24 and 15H4 (10(-9) or 10(-8) M with two immunizing peptides and 10(-8) M with two nonimmunizing HVR1 peptides) paralleled the reactivity obtained with peptide enzyme immunoassay. MAbs 2P24 and 15H4 captured 25 of 31 (81%) HCV in unselected patients' plasmas. These antibodies also blocked HCV binding to Molt-4 cells in a dose-dependent fashion. The data presented suggest that broadly cross-reactive MAbs to a conserved epitope within HCV HVR1 can be produced. Clinical application for passive immunization in HCV-related chronic liver disease and after liver transplantation is considered.

A complex human immunodeficiency virus type 1 A/G/J recombinant virus isolated from a seronegative patient with AIDS from Benin, West Africa

A human immunodeficiency virus type 1 (HIV-1(B76)) originating from Benin (West Africa) was isolated and characterized. The patient had severe clinical AIDS and presented an unusual serological profile. Only one out of five different detection assays was able to demonstrate the presence of antibodies to HIV, whereas confirmatory assays remained indeterminate. In contrast, both plasma viral load and p24 antigen level were unusually high. HIV-1 infection was proved by viral RNA and proviral DNA amplification. HIV-1(B76) partially purified lysate reacted strongly with all anti-HIV-1-positive sera from the region but B76 plasma did not react with subtype A control viral antigen. This patient is likely to have had severe acquired immune dysfunction explaining her lack of immunological reactivity. Phylogenetic analysis of the genome identified a complex HIV-1 A/G/J recombinant. The gag and pol genes, and the majority of nef,are characteristic of subtype A; the gag/pol junction, the 3' end of pol, vpu and env genes were characteristic of subtype G; vif, vpr and the 5' end of nef were subtype J. In addition, part of the HIV-1(B76) genome had considerable sequence similarity with the previously described CRF06 cpx (BFP90) isolate. HIV-1(B76) did not exhibit any remarkable replication properties or cell tropism in vitro.

AIDS in an HIV-seronegative Ghanaian woman with intersubtype A/G recombinant HIV-1 infection

A 29-year-old Ghanaian woman who developed AIDS while being HIV-antibody seronegative was investigated during a collaborative study aimed at the identification of viral causes of a HIV-seronegative AIDS syndrome in West Africa. Plasma was screened with a panel of EIA tests for antibodies to HIV and HIV-1 p24 antigen. Retroviral infection was investigated by detection of reverse transcriptase (RT) activity in plasma, viral RNA amplification and quantification, and virus isolation. Positive amplification products were sequenced and phylogenetic analyses were carried out. Most EIA tests were unable to demonstrate the presence of anti-HIV anti-bodies, whereas confirmatory assays yielded inconclusive results. Retroviral infection was documented by detection of RT activity, HIV-1-specific genomic amplification and virus isolation. This virus was HIV-1 subtype A with an unusual six amino acid insertion in the gp120 V4 loop and with the nef gene of subtype G. The patient's plasma did not react with either autologous or heterologous viral lysates or HIV-1 peptides, whereas antibodies to other viral antigens were present. In conclusion, the Ghanaian patient exhibited a rare subtype A/G recombinant HIV-1 infection with a near absence of a HIV-specific humoral response. The lack of detectable antibody response might be due to either a highly pathogenic, rapidly fatal, HIV-1 infection preventing the development of the typical humoral immune response or to a host-related dysfunction of the immune system. Direct antigenemia or genomic detection of the virus should be undertaken when clinical or biological data suggests an HIV infection in the absence of serological evidence.