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Influenza-like illness (ILI) is an important public health problem worldwide. In the Central African Republic, acute infectious diseases are the commonest reason for consultation. The Institut Pasteur of Bangui set up a surveillance network in 2008 to monitor the circulation of influenza viruses. We report the results of use of this surveillance system during the period 2010–2015. The first surveillance centre covered Bangui, the capital of the country, and neighbouring areas and epidemiological data on syndromes similar to ILI. Throat and nasopharyngeal swab samples are transmitted weekly to the Institut Pasteur of Bangui, where real-time and multiplex reverse transcription polymerase chain reaction are used to detect and subtype influenza A (H1N1 and H3N2) and B viruses. The demographic characteristics of all patients and of positive cases according to age and the seasonal patterns of influenza virus circulation were analysed. Between January 2010 and December 2015, 5385 throat swabs were collected; 454 (8.4%) of the samples were positive. Of these, 450 yielded at least one influenza virus and four showed co-infections. Children under the age of 5 years were the most frequently infected (257/450, 57.1%), with irregular peaks of ILI. Influenza B predominated (56.2%; n= 201), with 39.0% H3N2 and 16.7%H1N1pdm09. Influenza viruses were detected mainly in the rainy season (July–December). The sentinel surveillance site is yielding important information about the seasonality and age pattern of circulating influenza virus. Nationwide distribution of sentinel sites is warranted.

New sequencing technologies have opened the way to the discovery and the characterization of pathogenic viruses in clinical samples. However, the use of these new methods can require an amplification of viral RNA prior to the sequencing. Among all the available methods, the procedure based on the use of Phi29 polymerase produces a huge amount of amplified DNA. However, its major disadvantage is to generate a large number of chimeric sequences which can affect the assembly step. The pre-process method proposed in this study strongly limits the negative impact of chimeric reads in order to obtain the full-length of viral genomes. Three different assembly softwares (ABySS, Ray and SPAdes) were tested for their ability to correctly assemble the full-length of viral genomes. Although in all cases, our pre-processed method improved genome assembly, only its combination with the use of SPAdes allowed us to obtain the full-length of the viral genomes tested in one contig. The proposed pipeline is able to overcome drawbacks due to the generation of chimeric reads during the amplification of viral RNA which considerably improves the assembling of full-length viral genomes.

ABSTRACTThe prevalence of hepatitis B virus (HBV) surface antigen was significantly higher in urban (12.9%) than in rural (7.6%) populations (P= 0.003), but no difference was found in the prevalence of hepatitis delta virus (HDV), which was high in both populations. Phylogenetic analysis showed the circulation of HBV-A3 and -E genotypes and the presence of HDV-1, HDV-7, and HDV-8 clades.

ABSTRACTA single-tube, multiplex, real-time PCR assay with molecular beacons was established in which various probes were used for the simultaneous detection, differentiation, and quantification of human T-cell leukemia virus types 1, 2, and 3 (HTLV-1, HTLV-2, and HTLV-3, respectively) and of simian T-cell leukemia virus types 1 and 3 (STLV-1 and STLV-3, respectively). The quantitative amplification of the standards with MT4 (HTLV-1) and C19 (HTLV-2) cell lines and a molecular clone of HTLV-3 was linear, with the simplex and multiplex methods having similar efficiencies. A maximum difference of 0.9 (mean, 0.4; range, 0.0 to 0.9) was found between threshold cycle values in single and multiplex reactions. The efficiency with each probe in the multiplex reaction was close to 100%, indicating strong linear amplification. The albumin gene was used to standardize the copy number. Comparable results for the detection and quantification of HTLV-1 were obtained with our new methods and with other real-time PCR methods described previously. With our new multiplex assay, however, we were able to detect and quantify HTLV-2 and -3 and STLV-1 and -3 in clinical specimens, with an excellent dynamic range of 106to 100copies per assay, which the other assays could not do. Thus, it will be possible to determine a wide range of HTLV types in both standard and clinical samples, with a detection of 1 to 10 HTLV copies in samples containing at least 100 cells. Furthermore, our system can provide evidence for multiple infections with the three HTLV types, with separate proviral load results. Our new method also could be used for epidemiological studies in Africa and in countries where HTLVs and STLVs are endemic.

ABSTRACTHuman T-cell leukemia virus type 1 (HTLV-1) is highly endemic in areas of central Africa; mother-to-child transmission and sexual transmission are considered to be the predominant routes. To determine the prevalence and subtypes of HTLV-1/2 in pregnant women in Gabon, we conducted an epidemiological survey in the five main cities of the country. In 907 samples, the HTLV-1 seroprevalence was 2.1%, which is lower than that previously reported. Only one case of HTLV-2 infection was found. The HTLV-1 seroprevalence increased with age and differed between regions (P= 0.05), with the highest prevalence (5%) in the southeastern region. A wide range of HTLV-1 proviral loads was observed among the infected women. The level of the proviral load was correlated with a high HTLV-1 antibody titer (P= 0.02). Sequencing of HTLV-1 envand long terminal repeat fragments showed that all but one strain belonged to the central African subtype B; the outlier was of cosmopolitan subtype A. The new strains of subtype B exhibited wide genetic diversity, but there was no evidence of clustering of specific genomes within geographical regions of the country. Some strains were closely related to simian T-cell leukemia virus type 1 strains of great apes, suggesting that in these areas some HTLV-1 strains could arise from relatively recent interspecies transmission. The sole HTLV-2 strain belonged to subtype B. In this study we showed that the prevalence of HTLV-1 in the southeast is one of the highest in the world for pregnant women.

Human T-cell leukemia virus type 1 (HTLV-1) is highly endemic in areas of central Africa; mother-to-child transmission and sexual transmission are considered to be the predominant routes. To determine the prevalence and subtypes of HTLV-1/2 in pregnant women in Gabon, we conducted an epidemiological survey in the five main cities of the country. In 907 samples, the HTLV-1 seroprevalence was 2.1%, which is lower than that previously reported. Only one case of HTLV-2 infection was found. The HTLV-1 seroprevalence increased with age and differed between regions (P ≤ 0.05), with the highest prevalence (5%) in the southeastern region. A wide range of HTLV-1 proviral loads was observed among the infected women. The level of the proviral load was correlated with a high HTLV-1 antibody titer (P ≤ 0.02). Sequencing of HTLV-1 env and long terminal repeat fragments showed that all but one strain belonged to the central African subtype B; the outlier was of cosmopolitan subtype A. The new strains of subtype B exhibited wide genetic diversity, but there was no evidence of clustering of specific genomes within geographical regions of the country. Some strains were closely related to simian T-cell leukemia virus type 1 strains of great apes, suggesting that in these areas some HTLV-1 strains could arise from relatively recent interspecies transmission. The sole HTLV-2 strain belonged to subtype B. In this study we showed that the prevalence of HTLV-1 in the southeast is one of the highest in the world for pregnant women.

An hepatitis B virus (HBV) molecular survey was conducted in five remote villages in the equatorial forest in Gabon, Central Africa. Two hundred seventy out of 311 inhabitants (86.8%) were HBV‐infected or had evidence of past HBV infection. Chronic hepatitis corresponding to hepatitis B surface antigen (HBsAg) positivity was suspected in 27 (8.6%) of the HBV‐infected subjects. High HBV viral loads were detected mainly in children aged 4–7 years. The pre‐S/S domains were sequenced in 13 cases and 12 strains belonged to HBV‐A genotype. In one case we found evidence for recombination between genotypes A and E. Phylogenetic analysis revealed that Gabonese HBV strains were distinct from HBV‐A subgenotypes (A1 and A2). These new HBV strains from Gabon clustered with previously reported HBV‐A3 subgenotype strains from Cameroon and Democratic Republic of Congo. The analysis of the pre‐S2 domain allowed us to determine two amino acid substitutions (N/152/S and N/174/T) specific to the Central African HBV‐A3 subgenotype strains and one amino acid substitution (P/155/Q) unique to these new Gabonese HBV‐A3 subgenotype isolates. Two full genome sequences of two new Gabonese HBV isolates are also presented and confirm the distinctive HBV‐Gab‐A3 cluster. J. Med. Virol. 78:1175–1184, 2006. © 2006 Wiley‐Liss, Inc.

In immortal cells, the existence of a mechanism for the maintenance of telomere length is critical. In most cases this is achieved by the reactivation of telomerase, a cellular reverse transcriptase that prevents telomere shortening. Here we report that the telomerase gene (hTERT) promoter is up-regulated during transmission of human T-cell lymphotropic virus type-I (HTLV-I) to primary T cells in vitro and in ex vivo adult T-cell leukemia/lymphoma (ATLL) samples, but not asymptomatic carriers. Although Tax impaired induction of human telomerase reverse transcriptase (hTERT) mRNA in response to mitogenic stimulation, transduction of Tax into primary lymphocytes was sufficient to activate and maintain telomerase expression and telomere length when cultured in the absence of any exogenous stimulation. Transient transfection assays revealed that Tax stimulates the hTERT promoter through the nuclear factor κB (NF-κB) pathway. Consistently, Tax mutants inactive for NF-κB activation could not activate the hTERT or sustain telomere length in transduced primary lymphocytes. Analysis of the hTERT promoter occupancy in vivo using chromatin immunoprecipitation assays suggested that an increased binding of c-Myc and Sp1 is involved in the NF-κB–mediated activation of the hTERT promoter. This study establishes the role of Tax in regulation of telomerase expression, which may cooperate with other functions of Tax to promote HTLV-I–associated adult T-cell leukemia.

In immortal cells, the existence of a mechanism for the maintenance of telomere length is critical. In most cases this is achieved by the reactivation of telomerase, a cellular reverse transcriptase that prevents telomere shortening. Here we report that the telomerase gene (hTERT)promoter is up-regulated during transmission of human T-cell lymphotropic virus type-I (HTLV-I) to primary T cells in vitro and in ex vivo adult T-cell leukemia/lymphoma (ATLL) samples, but not asymptomatic carriers. Although Tax impaired induction of human telomerase reverse transcriptase (hTERT) mRNA in response to mitogenic stimulation, transduction of Tax into primary lymphocytes was sufficient to activate and maintain telomerase expression and telomere length when cultured in the absence of any exogenous stimulation. Transient transfection assays revealed that Tax stimulates the hTERT promoter through the nuclear factor κB (NF-κB) pathway. Consistently, Tax mutants inactive for NF-κB activation could not activate the hTERT or sustain telomere length in transduced primary lymphocytes. Analysis of the hTERT promoter occupancy in vivo using chromatin immunoprecipitation assays suggested that an increased binding of c-Myc and Sp1 is involved in the NF-κB–mediated activation of the hTERT promoter. This study establishes the role of Tax in regulation of telomerase expression, which may cooperate with other functions of Tax to promote HTLV-I–associated adult T-cell leukemia.

ABSTRACTThe prevalence of human T-cell lymphotropic virus type 1 (HTLV-1) and HTLV-2 in blood donors in Guyana has never been estimated. We evaluated the prevalence of these viruses in blood donors by enzyme-linked immunosorbent assay and Western blotting and showed a prevalence of HTLV-1 of 1.3%; no HTLV-2 was detected. Female donors had a much higher HTLV-1 seroprevalence (3.6%) than male donors (0.7%). HTLV-1-seropositive donors tended to be slightly older than the average age for the total pool of donors. We also investigated the phylogenetic and molecular characteristics of HTLV-1 strains in Guyana and compared them with those identified in Suriname and French Guiana. Analysis of portions of the envand long terminal repeat nucleotide sequences showed that all the strains in Guyana and Suriname, like those in French Guiana, belonged to the transcontinental group of cosmopolitan subtype A. The similarities were greater between strains from Suriname and Guyana than between strains from Suriname and Guyana and those from French Guiana. Nevertheless, our results confirm that the HTLV-1 strains in all three countries have a common African origin.

ABSTRACTWe assessed the immunogenicities and efficacies of two highly attenuated vaccinia virus-derived NYVAC vaccine candidates encoding the human T-cell leukemia/lymphoma virus type 1 (HTLV-1) envgene or both the envand gaggenes in prime-boost pilot regimens in combination with naked DNA expressing the HTLV-1 envelope. Three inoculations of NYVAC HTLV-1 envat 0, 1, and 3 months followed by a single inoculation of DNAenvat 9 months protected against intravenous challenge with HTLV-1-infected cells in one of three immunized squirrel monkeys. Furthermore, humoral and cell-mediated immune responses against HTLV-1 Env could be detected in this protected animal. However, priming the animal with a single dose of envDNA, followed by immunization with the NYVAC HTLV-1 gagandenvvaccine at 6, 7, and 8 months, protected all three animals against challenge with HTLV-1-infected cells. With this protocol, antibodies against HTLV-1 Env and cell-mediated responses against Env and Gag could also be detected in the protected animals. Although the relative superiority of a DNA prime-NYVAC boost regimen over addition of the Gag component as an immunogen cannot be assessed directly, our findings nevertheless show that an HTLV-1 vaccine approach is feasible and deserves further study.

We investigated the characterization of different HIV-1 subtypes present in French Guiana by use of three different methods. Serological methods were used for the initial screening, which were then confirmed by the heteroduplex mobility assay (HMA). The V3 env region was subsequently sequenced for phylogenetic analysis, to confirm the subtype of the samples, and to assign a subtype to samples that gave results that were difficult to interpret or discordant by serology or HMA. A total of 221 HIV-1 seropositive samples were typed; 110 of them were confirmed by HMA and 16 were sequenced. Of the 221 samples tested 210 patients (95%) were found to be infected with subtype B, 10 (4.5%) were infected with subtype A, and one patient was infected with subtype F. Phylogenetic analysis demonstrated that the strains from French Guiana were closely related to the subtype A and B subtypes, and that one strain was closely related to an F subtype (100% bootstrap value). Four strains from French Guiana clustered in the subtype A (99% bootstrap value) and the other strains were associated with subtype B (100% bootstrap value). The geographic position of French Guiana suggested that HIV-1 was probably introduced into the country via several routes, and thus the pattern of the HIV-1 epidemic might evolve in the near future.

Extensive studies have been carried out on native Amerindian populations living in French Guiana in an attempt to detect human T cell leukemia virus type 2 (HTLV-2). However, the first strain of this virus identified in this region was not detected in these populations, but in a Brazilian woman of Amerindian origin. Comparative analyses of the nucleotide sequences of 589 bp of the gp21 env gene and of 625 bp of the long terminal repeat (LTR) showed that this new HTLV-2 strain (HTLV-2 GUY) was of subtype A. Sequence comparison and phylogenetic analyses demonstrated that HTLV-2 GUY was closely related to a group of distinct variants of HTLV-2 subtype A strains originating mostly from Brazilian inhabitants and formerly called HTLV-2 subtype C. As there is a high level of immigration from Brazil in French Guiana, we carried out a seroepidemiological study of 175 Brazilians, mostly women (obtained from a serum databank) and 72 female Brazilian prostitutes living in French Guiana to determine whether HTLV-2 is likely to become an emerging infection in this area. No HTLV-2 infection was detected, indicating that this virus is unlikely to become prevalent in the near future.

ABSTRACTAfter experimental infection of squirrel monkeys (Saimiri sciureus) with human T-cell leukemia virus type 1 (HTLV-1)-infected cells, the virus is transcribed only transiently in circulating blood, spleen, and lymph nodes. Stable disappearance of viral expression occurs at 2 to 3 weeks after inoculation. This coincides with the development of the anti-HTLV-1 immune response and persistent detection of the provirus in peripheral blood mononuclear cells (PBMCs). In this study, the HTLV-1 replication pattern was analyzed over time in PBMCs and various organs from two HTLV-1-infected squirrel monkeys. Real-time quantitative PCR confirmed that PBMCs and lymphoid organs constitute the major reservoirs for HTLV-1. The PCR amplification of HTLV-1 flanking sequences from PBMCs evidenced a pattern of clonal expansion of infected cells identical to that observed in humans. Dissemination of the virus in body compartments appeared to result from cellular transport of the integrated provirus. The circulating proviral burden increased as a function of time in one animal studied over a period of 4 years. The high proviral loads observed in the last samples resulted from the accumulation of infected cells via the extensive proliferation of a restricted number of persistent clones on a background of polyclonally expanded HTLV-1-positive cells. Therefore, HTLV-1 primary infection in squirrel monkeys is a two-step process involving a transient phase of reverse transcription followed by persistent multiplication of infected cells. This suggests that the choice of the target for blocking HTLV-1 replication might depend on the stage of infection.

We show that the squirrel monkey Saimiri sciureus is susceptible to experimental infection with either syngeneic or allogeneic HTLV-1-immortalized cells. As in humans, such experimental inoculation leads to chronic infection, and HTLV-1 provirus was detected in PBMCs by PCR. Chronically infected monkeys developed high titers of antibodies against the structural proteins of the virus, as do HTLV-1-infected humans. Furthermore, in serially sacrificed squirrel monkeys infected with HTLV-1, proviral DNA was detected at primary phases of infection in PBMCs, spleens, and lymph nodes. Tax/rex mRNA was also detected by RT-PCR in the PBMCs of two monkeys at 12 days after inoculation and in the spleen and lymph nodes of the monkey sacrificed on Day 12. In this animal, scattered HTLV-1-tax/rex mRNA-positive lymphocytes were detected by in situ hybridization in frozen sections of the spleen. These results indicate that PBMCs, spleen, and lymph nodes serve as major reservoirs for HTLV-1 during the early phase of infection. To evaluate the relationship between viral expression and the immune response during infection, humoral and cytotoxic T cell responses (CTL) were studied at various times after inoculation. Antibodies to HTLV-1 were detected 3 weeks after infection and anti-p40Tax and anti-Env CTL activity was detected 2 months after infection and remained detectable thereafter. Our results indicate that the squirrel monkey provides a useful animal model for studying the pathogenesis of HTLV-1 and for evaluating new candidate vaccines.

The aim of this study was to investigate the distribution of human T-cell leukemia virus type 1 (HTLV-1) in various organs of serially sacrificed squirrel monkeys (Saimiri sciureus) in order to localize the reservoir of the virus and to evaluate the relationship between viral expression and the humoral or cellular immune response during infection. Six squirrel monkeys infected with HTLV-1 were sacrificed 6, 12, and 35 days and 3, 6, and 26 months after inoculation, and 20 organs and tissues were collected from each animal. PCR and reverse transcription-PCR (RT-PCR) were performed withgagand taxprimers. Proviral DNA was detected by PCR in peripheral blood mononuclear cells (PBMCs) of monkeys sacrificed 6 days after inoculation and in PBMCs, spleens, and lymph nodes of monkeys sacrificed 12 and 35 days and 3, 6, and 26 months after inoculation. Furthermore, tax/rexmRNA was detected by RT-PCR in the PBMCs of two monkeys 8 to 12 days after inoculation and in the spleens and lymph nodes of the monkey sacrificed on day 12. In this animal, scattered HTLV-1 tax/rexmRNA-positive lymphocytes were detected by in situ hybridization in frozen sections of the spleen, around the germinal centers and close to the arterial capillaries. Anti-HTLV-1 cell-mediated immunity was evaluated at various times after inoculation. Anti-p40Taxand anti-Env cytolytic T-cell responses were detected 2 months after infection and remained detectable thereafter. When Tax peptides were used, this response appeared to be directed against various Tax epitopes. Our results indicate that squirrel monkeys represent a promising animal model for studying the early events of HTLV-1 infection and for evaluating candidate vaccines against HTLV-1.

The complete human T-cell leukemia virus type I (HTLV-I) env gene was inserted into an expression cassette containing the adenovirus 5 major late promoter (Ad5-MLP). Recombinant Ad5-HTLV-I-env was obtained by homologous recombination in 293 cells simultaneously transfected by the expression cassette and the genomic DNA of Ad5. In vitro expression of the HTLV-I-env gene in the recombinant vector was detected by immunofluorescence and Western blotting. Functional expression of HTLV-I-env was confirmed by syncitium formation specifically in HeLa cells infected with Ad5-HTLV-I-env. Two immunization regimens against HTLV-I were tested in WKY and Fischer F-344 rats. The first involved WKY rats primed with Ad5-HTLV-I-env or naked DNA plasmids containing the HTLV-I-env gene and boosted with Ad5 containing the HTLV-I-env gp46 gene or with baculovirusderived recombinant gp46. No antibody against HTLV-I was detected, while HTLV-I-specific cytotoxic T lymphocytes were recovered from all immunized groups but not from controls. The second approach involved Fischer F-344 rats primed and boosted with recombinant vaccinia virus containing the HTLV-I-env gene. Such rats developed antibodies against the HTLV-I env gp21 and gp46 (non-neutralizing). After challenge with human HTLV-I-producing cells (MT-2), both immunization regimens were found to induce partial protection. Int. J. Cancer 71:300–307, 1997. © 1997 Wiley-Liss, Inc.

In order to determine the prevalence of antibodies to hepatitis A, C, and E viruses (HAV, HCV, and HEV) in the various ethnic groups and areas of French Guiana, sera (996 for HCV and HEV, 941 for HAV) were tested for antibodies to these viruses using ELISAs.

Monoclonal antibodies (mAbs) were obtained against the surface antigens of theEimeria falciformis sporozoite by immunizing mice with whole homogenized sporozoite. The hybridomas were selected by their reactivities against oocyst extracts, then against glutaraldehyde-treated sporozoites. Three mAbs recognized both the surface ofE. falciformis, E. tenella, andE. acervulina and their refractile bodies, whereas a fourth mAb recognized only one epitope on the refractile bodies. All mAbs bound to the same immunoaffinity-purified antigens in Western-blot analysis (P27 forE. falciformis and P25 forE. tenella andE. acervulina). Thus, the mAbs define at least two shared epitopes between sporozoite antigens from different eimerian species. Two of these mAbs are involved in the in vitro phagocytosis ofE. falciformis sporozoites by macrophages and also in their lysis by neutrophils. Altogether, these properties showed that the four mAbs came from different activated B-cells. The P27 antigen recognized by our mAbs represents a major target of the in vitro destructive immune response.

Peripheral blood mononuclear cells (PBMC) from three adult male squirrel monkeys (Saı̈miri sciureus) were transformed by human T-cell leukemia/lymphoma virus type I (HTLV-I) by cocultivation with lethally irradiated human MT-2 cells. Three permanent monkey T-cell lines producing HTLV-I were obtained and characterized. Six weeks after inoculation seroconversion was observed in three of three monkeys inoculated with autologous transformed T cells and in two of three monkeys receiving homologous cells. Proviral DNA was detected in their PBMC at various times after inoculation, with the highest proviral load and antibody titers being found in monkeys infected with homologous cells. Monkeys inoculated with heterologous MT-2 cells did not seroconvert, and HTLV-I provirus was detected only transiently in their PBMC. To determine whetherin vitroandin vivoHTLV-I infection of squirrel monkey cells led to a selection of monkey-adapted viral mutants, comparative sequencing of the proviral gp21envbetweenex vivomonkey HTLV-I-infected PBMC, the inoculum, and MT-2 cells was done and no significant differences were detected. The squirrel monkey, which is naturally free of simian T-cell leukemia/lymphoma virus, thus appears to be a suitable model for evaluating HTLV-I candidate vaccines and for studying the pathogenesis of HTLV-I.

Three aspects of the rat model of HTLV-I/II infection were investigated. (i) The efficacy of HTLV-I-transformed rat cell lines in infecting different strains of rats: WKY and Lewis HTLV-I-transformed cell lines were injected into adult WKY, Lewis and Brown Norway rats, representing syngeneic and allogeneic combinations. The HTLV-I provirus was not detected in peripheral-blood mononuclear cells (PBMC) from these rats 18 weeks after inoculation, showing that HTLV-I-transformed rat cells are not suitable for virus challenge in vaccination experiments. Rats inoculated with Lewis HTLV-I-transformed cells produced an antibody response to HTLV-I, which was higher in allogeneic (WKY and Brown Norway) than in syngeneic rats. (ii) The susceptibility of rats to HTLV-II infection: After human HTLV-II-producing cells (MO) were injected into adult WKY rats, the HTLV-II provirus was detected in PBMC 12 weeks later. Sequencing of a portion of this provirus confirmed its identity with the HTLV-II from MO cells. (iii) The role of MHC haplotype in susceptibility to neurological disease in rats inoculated as newborns with HTLV-I: The hypothesis that the RT-I^k haplotype confers susceptibility was tested by inoculating newborn OKA (RT-I^k), WKY (RT-I^l), Lewis (RT-I^l) and Fischer 344 (RT-I^lvl) rats with human HTLV-I-producing cells (MT-2). Eighteen months later, only the WKY rats showed histological abnormality of the spinal cord, without clinical paralysis. Fischer 344 rats developed cutaneous tumors and OKA rats mammary tumors. The HTLV-I provirus was not detected in these tumors. Int. J. Cancer 73:131–136, 1997. © 1997 Wiley-Liss, Inc.

ABSTRACTHepatitis B virus (HBV) surface antigen (HBsAg) was found in 9.2% of 1,186 pregnant women from Gabon, of whom 10.1% had the HBe antigen and 89.9% had anti-HBe antibodies. Antibodies to the hepatitis delta virus (HDV) were found in 15.6% of the HBsAg-positive women. The HBV strains were of the A3 and E genotypes. The HDV strains belonged to HDV clades 1 and 8. These results provide clear evidence that HDV clade 8 is indigenous to Africa.