HIV-1 group P infection: towards a dead-end infection?

OBJECTIVES: HIV/1 group P (HIV-1/P) is the last HIV/1 group discovered and, to date, constitutes only two strains. To obtain new insight into this divergent group, we screened for new infections by developing specific tools, and analysed phenotypic and genotypic properties of the prototypic strain RBF168. In addition, the follow-up of the unique infected patient monitored so far has raised the knowledge of the natural history of this infection and its therapeutic management. DESIGN/METHODS: We developed an HIV-1/P specific seromolecular strategy and screened over 29 498 specimen samples. Infectivity and evolution of the gag-30 position, considered as marker of adaptation to human, were explored by successive passages of RBF168 strain onto human peripheral blood mononuclear cells. Natural history and immunovirological responses to combined antiretroviral therapy (cART) were analysed based on CD4+ cells and plasmatic viral load evolution. RESULTS: No new infection was detected. Infectivity of RBF168 was found lower, relative to other main HIV groups and the conservative methionine found in the gag-30 position revealed a lack of adaptation to human. The follow-up of the patient during the 5-year ART-free period, showed a relative stability of CD4+ cell count with a mean of 326 cells/µl. Initiation of cART led to rapid RNA undetectability with a significant increase of CD4+ cells, reaching 687 cells/µl after 8 years. CONCLUSION: Our results showed that HIV-1/P strains remain extremely rare and could be less adapted and pathogenic than other HIV strains. These data lead to the hypothesis that HIV-1/P infection could evolve towards, or even already corresponds to, a dead-end infection.

The Two-Phase Emergence of Non Pandemic HIV-1 Group O in Cameroon.

Unlike the pandemic form of HIV-1 (group M), group O viruses are endemic in west central Africa, especially in Cameroon. However, little is known about group O's genetic evolution, and why this highly divergent lineage has not become pandemic. Using a unique and large set of group O sequences from samples collected from 1987 to 2012, we find that this lineage has evolved in successive slow and fast phases of diversification, with a most recent common ancestor estimated to have existed around 1930 (1914-1944). The most rapid periods of diversification occurred in the 1950s and in the 1980s, and could be linked to favourable epidemiological contexts in Cameroon. Group O genetic diversity reflects this two-phase evolution, with two distinct populations potentially having different viral properties. The currently predominant viral population emerged in the 1980s, from an ancient population which had first developed in the 1950s, and is characterized by higher growth and evolutionary rates, and the natural presence of the Y181C resistance mutation, thought to confer a phenotypic advantage. Our findings show that although this evolutionary pattern is specific to HIV-1 group O, it paralleled the early spread of HIV-1 group M in the Democratic Republic of Congo. Both viral lineages are likely to have benefited from similar epidemiological contexts. The relative role of virological and social factors in the distinct epidemic histories of HIV-1 group O and M needs to be reassessed.

HTLV-2B strains, similar to those found in several Amerindian tribes, are endemic in central African Bakola Pygmies.

BACKGROUND: The presence and origin of endemic foci of human T-lymphotropic virus type 2 (HTLV2) infection in Africa remain a matter of debate. METHODS: To better appreciate such determinants, we performed a survey of 1918 inhabitants from Cameroon forest areas, including 1051 Bakola Pygmies and 867 Bantus. RESULTS: The overall HTLV-1/2 seroprevalence was 4% (49 cases of HTLV-1 and 27 cases of HTLV-2 infection). Both infections were mainly restricted to the Bakola Pygmies, with surprisingly no HTLV-2 infections in the Bantu population. Both HTLV-1 and HTLV-2 seroprevalences increased with age. There was evidence of ongoing HTLV-2 transmission in this population. Lymphoid T cell lines producing HTLV-2 were established. HTLV-2 long terminal repeat sequences (672 base pairs) obtained from 7 infected Bakola were highly similar to each other (<1% nucleotide divergence), as well as to Amerindian HTLV-2B strains. Analyses on a complete sequence (8954 base pairs) confirmed that it was a typical HTLV-2 subtype B strain. Along with molecular clock analysis, these data strongly suggest that HTLV-2 has been endemic in the Bakola Pygmy population for a long time. CONCLUSIONS: This study demonstrates clearly an HTLV-2 endemicity with ongoing transmission in an African population. Furthermore, it give insights into central questions regarding the origins and evolution rate of HTLV-2 and the migrations of infected populations.

Complete-genome analysis of hepatitis B virus from wild-born chimpanzees in central Africa demonstrates a strain-specific geographical cluster.

In order to determine whether geographical or species clustering accounts for the distribution of hepatitis B virus (HBV) in subspecies of chimpanzees in Africa, four complete chimpanzee HBV (ChHBV) genome sequences were obtained from eight hepatitis B surface antigen-positive wild-born chimpanzees from Cameroon, Republic of Congo and Gabon. The serological profiles of these chimpanzees corresponded to the acute or chronic highly replicative phase of HBV infection, as confirmed by high plasma HBV loads. Analysis of the sequence alignment of 256 aa (S region) from the eight HBV-infected chimpanzees allowed us to determine the HBV amino acid patterns specific to each chimpanzee subspecies and to their geographical origin. Phylogenetic analysis of both the S region and the complete genome confirmed this distinctive clustering of eight novel ChHBV strains within Pan troglodytes. The strong phylogenetic associations of ChHBV sequences with both chimpanzee subspecies and their geographical origin were therefore confirmed.

Simian foamy virus transmission from apes to humans, rural Cameroon.

Simian virus infections of humans are an increasing public health concern. Simian foamy virus (SFV) infections have been reported in persons occupationally exposed to nonhuman primates and in a few hunters in Cameroon. To better understand this retroviral zoonosis in natural settings, we studied persons who lived in southern Cameroon, near nonhuman primate habitats. First we studied a general population of 1,164 adults; 4 were SFV positive according to serologic and molecular assays. Then we studied 85 persons who reported having been bitten or scratched by nonhuman primates; 7/29 (24.1%) of those who had contact with apes (gorillas or chimpanzees) were SFV positive, compared with only 2/56 (3.6%) of those who had had contact with monkeys. These data demonstrate efficient transmission of SFVs to humans in natural settings in central Africa, specifically following ape bites, and viral persistence in the human host.

Detection and molecular characterization of foamy viruses in Central African chimpanzees of the Pan troglodytes troglodytes and Pan troglodytes vellerosus subspecies.

BACKGROUND: Foamy viruses are exogenous retroviruses that are highly endemic in non-human primates (NHPs). Recent studies, mainly performed in North America, indicated frequent simian foamy virus (SFV) infection in persons occupationally exposed to NHPs. This zoonotic infection was demonstrated mainly after bites by chimpanzees [Pan troglodytes (P. t.)] of the West African P. t. verus subspecies in primatology centers or zoos in the USA. METHODS: We studied 32 chimpanzees from the Central African subspecies P. t. troglodytes and P. t. vellerosus, originating from Cameroon (29 cases) or Gabon (3 cases). We screened first plasma or sera of the animals with a Western blot detecting the SFVs Gag doublet proteins. Then, we performed two nested polymerase chain reactions (PCRs) amplifying a fragment of the integrase and LTR regions and, finally, we made phylogenetical analyses on the sequences obtained from the integrase PCR products. RESULTS: By serological and/or molecular assays, we detected foamy viruses (FVs) infection in 14 chimpanzees. Sequence comparison and phylogenetic analyses of a 425 bp fragment of the integrase gene obtained for 10 of the 14 positive apes, demonstrated a wide diversity of new FVs strains that belong phylogenetically either to the P. t. troglodytes or P. t. vellerosus foamy viral clade. CONCLUSIONS: This study shows that chimpanzees living in these areas of Central Africa are infected by several specific foamy viruses. This raises, in such regions, the potential risk of a human retroviral infection of zoonotic origin linked to chimpanzees contacts, as already exemplified for STLV-1 and SIV infections.

Endemic versus epidemic viral spreads display distinct patterns of HTLV-2b replication.

As the replication pattern of leukemogenic PTLVs possesses a strong pathogenic impact, we investigated HTLV-2 replication in vivo in asymptomatic carriers belonging into 2 distinct populations infected by the same HTLV-2b subtype. They include epidemically infected American blood donors, in whom HTLV-2b has been present for only 30 years, and endemically infected Bakola Pygmies from Cameroon, characterized by a long viral endemicity (at least few generations). In blood donors, both the circulating proviral loads and the degree of infected cell proliferation were largely lower than those characterizing asymptomatic carriers infected with leukemogenic PTLVs (HTLV-1, STLV-1). This might contribute to explain the lack of known link between HTLV-2b infection and the development of malignancies in this population. In contrast, endemically infected individuals displayed high proviral loads resulting from the extensive proliferation of infected cells. The route and/or the duration of infection, viral genetic drift, host immune response, genetic background, co-infections or a combination thereof might have contributed to these differences between endemically and epidemically infected subjects. As the clonality pattern observed in endemically infected individuals is very reminiscent of that of leukemogenic PTLVs at the pre-leukemic stage, our results highlight the possible oncogenic effect of HTLV-2b infection in such population.

Increased prevalence of leukocytes and elevated cytokine levels in semen from Schistosoma haematobium-infected individuals.

In this study, we investigated the seminal inflammatory response to egg infestation of the urogenital organs in 240 semen-donating men aged 15-49 years living in a Schistosoma haematobium-endemic area of Madagascar. In 29 subjects (12%) with excretion of > or =5 ova/ejaculate, leukocytospermia (>10(6) leukocytes/mL) and the presence of seminal lymphocytes and eosinophil leukocytes were each significantly more prevalent than in 74 subjects (31%) who were S. haematobium negative (P<.01). In addition, seminal levels of interleukin (IL)-4, IL-6, IL-10, and tumor necrosis factor- alpha were significantly higher among seminal egg-excreting subjects than among infection-negative subjects (P<.001). Sexually transmitted infection (STI) with Neisseria gonorrhoeae, Chlamydia trachomatis, Mycoplasma genitalium, and/or Trichomonas vaginalis did not act as a confounding factor for the observed associations. At follow-up, 6 months after systematic antischistosomiasis and STI syndrome treatment at baseline, the prevalence of seminal leukocytes decreased significantly among the previously seminal egg-positive subjects. The same tendency was observed for the posttreatment levels of cytokines. Numerous studies have already shown an association between STI-associated genital inflammation and human immunodeficiency virus (HIV) propagation. Therefore, the results of the present study suggest that male urogenital schistosomiasis may constitute a risk factor for HIV transmission, as a result of egg-induced inflammation in the semen-producing pelvic organs.

Hepatitis C virus infection in cameroon: A cohort-effect.

A hepatitis C virus (HCV) serological study conducted in 2003 on 1,434 individuals in Yaounde and other HCV seroepidemiological studies on 2,066 sera sampled between 1993 and 1997 in four geographically distinct rural areas (Ntem, Mekas, Yokadouma, and Nditam) in Cameroon, are described. Two patterns of HCV seroprevalence were observed. The first pattern, represented by Nditam and Yokadouma populations, showed low HCV seroprevalence rates (2.9% and 3.3%, respectively) increasing moderately with age (9.0% and 16.7% after age 50). The second pattern showed high seroprevalence rates (6.9% for Yaounde, 14.4% and 16.7% for Ntem and Mekas, respectively). These rates increased dramatically with age (32.8%-49.5% after age 50). The age-specific anti-HCV prevalence curve of the 1993 Mekas survey paralleled those of the 1997 Ntem and 2003 Yaounde surveys. Using the year of birth as the x-axis, the three curves closely matched each other. This clearly indicates a cohort effect for which the seroprevalence trends are clearly related with the year of birth, rather than the age. The highest prevalence was observed among people born around 1940.

Natural simian foamy virus infection in wild-caught gorillas, mandrills and drills from Cameroon and Gabon.

A survey for the presence of simian foamy retroviruses (SFVs) was performed in 44 wild-caught apes and monkeys, including 27 gorillas, 11 mandrills and six drills, originating from south Cameroon or Gabon. Combined serological and/or nested-PCR assays indicated SFV infection among five Gorilla gorilla gorilla, seven Mandrillus sphinx and two Mandrillus leucophaeus. Sequences of a 425 bp fragment of the integrase gene were obtained for 11 animals. Phylogenetic studies indicated that strains from gorillas, mandrills and drills each formed a highly supported phylogenetic clade with, moreover, the existence of two different gorilla SFVs. This study demonstrates for the first time that these animals are naturally infected with specific SFVs. In the context of simian-to-human interspecies transmission, the results confirm that such viruses can also infect humans, as the SFVs identified in wild-caught animals were the same as those recently reported as infecting hunters living in the same geographical areas.

[A network RER rooted on in vitro readout assays of Plasmodium falciparum sensitivity to chloroquine in the Indian Ocean Region]. / Evaluation in vitro de la sensibilité de Plasmodium falciparum à la chloroquine dans la région de l'océan Indien dans le cadre du réseau d'étude de la résistance (RER).

Chloroquine has been used as a first line drug to treat uncomplicated malaria cases during the last five decades in Madagascar and in the Comoros Union. The four plasmodial species known to infect humans occur on Madagascar Island. Chloroquine-resistant malaria cases, sometimes only suspected from presumptive malaria cases, have been reported in both countries. Thus, to redefine a strategy and a policy to cure malaria, there is a need to get relevant and updated data. In December 1999, the Madagascan Ministry of Health and the Institut Pasteur de Madagascar formed a network named RER for malaria resistance surveillance. In 2000 and 2001, 18 study sites (17 throughout Madagascar and 1 in Comoros) joined this network. Health-care workers were trained mainly for malaria diagnosis through the use of blood smear examination and for malaria case management. To alleviate the lack of competent medical teams within the health centres, and for technical and logistic reasons, as part of the network activities, it was decided to start with in vitro tests to assess the sensitivity of P.falciparum isolates to chloroquine by means of the isotopic method. Parasitized blood samples were collected from consenting patients. P.falciparum isolates were more predominant (989/1,036). Out of the 564 tests done, 432 (76.6%) could be assessed. Results demonstrated that 94.3% (381/404) of the Madagascan P.falciparum isolates were susceptible to chloroquine. In contrast, chloroquine-resistant isolates were prevalent in Comoros (8/28). The network set-up is presented. The usefulness of the in vivo approach and of the in vitro investigations (chemosusceptibility test and screening of mutations accounting for resistance to chloroquine) to monitor the emergence and the dissemination of chloroquine-resistant parasites is discussed.

Plasma viral RNA assay in HIV-1 group O infection by real-time PCR.

HIV-1 group O infections remains essentially restricted to central Africa, and particularly Cameroon, although isolated cases have been reported in Western countries. Genomic differences explain why commercial tests used to quantify HIV-1 group M plasma load are unsuitable for HIV-1 group O. This lack of a quantitative tool hinders the clinical management of HIV-O-infected patients. We have therefore developed a real-time PCR assay, based on LightCycler technology, to quantify HIV-1 group O RNA in plasma. The primers were selected in the LTR 3' region. Forty-eight plasma samples containing strains belonging to the different HIV-1 type O clades (O:A, O:B and O:C) were tested. RNA was quantifiable in 40 of these samples. RNA was always detected in samples from untreated patients, except for one patient infected by a highly divergent strain. The kinetics of plasma viral load were also examined in seven patients for whom clinical and immunologic follow-up data were available. HIV-1 group O plasma load was high in the absence of treatment and correlated negatively with the CD4 cell count. Serial samples obtained during treatment allowed us to compare viral load changes with immunologic outcome. Despite the high initial cost of acquiring the required cycling device, the per-sample cost of this real-time quantitative PCR assay for HIV-1 group O is low, making it suitable for use in endemic zones.

Plants traditionally prescribed to treat tazo (malaria) in the eastern region of Madagascar.

BACKGROUND: Malaria is known as tazo or tazomoka in local terminology in Madagascar. Within the context of traditional practice, malaria (and/or malaria symptoms) is commonly treated by decoctions or infusions from bitter plants. One possible approach to the identification of new antimalarial drug candidates is to search for compounds that cure or prevent malaria in plants empirically used to treat malaria. Thus, it is worth documenting the ethnobotanical data, and testing the antiplasmodial activity of the extractive from plants. METHODS: We interviewed traditional healers, known locally as ombiasy, at Andasibe in the eastern, rainy part of Madagascar. We recorded details of the preparation and use of plants for medicinal purposes. We extracted five alkaloids from Z. tsihanimposa stem bark, and tested them in vitro against Plasmodium falciparum FCM29. RESULTS: We found that traditional healers treat malaria with herbal remedies consisting of one to eight different plants. We identified and listed the medicinal plants commonly used to treat malaria. The plants used included a large number of species from different families. Zanthoxylum sp (Rutaceae) was frequently cited, and plants from this genus are also used to treat malaria in other parts of Madagascar. From the plant list, Zanthoxylum tsihanimposa, bitter plant endemic to Madagascar, was selected and examined. Five alkaloids were isolates from the stem bark of this plant, and tested in vitro against malaria parasite. The geometric mean IC50 values ranged from 98.4 to 332.1 micromolar. The quinoline alkaloid gamma-fagarine exhibited the strongest antiplasmodial activity. CONCLUSIONS: The current use of plants for medicinal purposes reflects the attachment of the Malagasy people to their culture, and also a lack of access to modern medicine. The possible extrapolation of these in vitro findings, obtained with plant extracts, to the treatment of malaria and/or the signs evoking malaria is still unclear. If plants are to be used as sources of novel antimalarial compounds, we need to increase our knowledge of their empirical use to improve plant selection. In the hope of preserving useful resources, we should now gather and record ethnobotanical data in Madagascar, and should try to bridge the gaps between empirics and realism.

Plasma RNA quantification and HIV-1 divergent strains.

The diversity of HIV complicates viral load measurement for patient management and treatment monitoring. Numerous studies have shown that non-B group M variants can be underestimated and that group O strains are not detected by commercial tests. More recent versions of the kits used for previous studies have improved the quantification of non-B variants but are still unable to detect or correctly quantify group O strains. In this study, the authors evaluated the new Abbott LCx HIV RNA Quantitative viral load kit with a large collection of samples from Europe and central Africa. One hundred thirty-three group M samples, including 69 from patients infected with non-B variants, and 70 group O samples were tested. The LCx system was compared with the Cobas Amplicor HIV-1 Monitor v1.5 test and with a quantitative real-time polymerase chain reaction method based on LightCycler technology. The LCx and Cobas tests had similar quantification ranges for group M samples and a high degree of linearity (r2 = 0.9582). The LCx method quantified group O variants (31 of the 48 patients were quantifiable) and gave values within the range of those obtained with the LightCycler assay. The two assays were sensitive but showed only moderate linearity (r2 = 0.6195), probably because of higher diversity of group O strains and the use of primers and probes in different regions. In conclusion, the authors showed that the LCx kit allowed quantification of the large group M diversity and group O variants.

Complete sequence of a novel highly divergent simian T-cell lymphotropic virus from wild-caught red-capped mangabeys (Cercocebus torquatus) from Cameroon: a new primate T-lymphotropic virus type 3 subtype.

Among 65 samples obtained from a primate rescue center located in Cameroon, two female adult red-capped mangabeys (Cercocebus torquatus) (CTO-602 and CTO-604), of wild-caught origin, had a peculiar human T-cell lymphotropic virus type 2 (HTLV-2)-like Western blot seroreactivity (p24, RGD21, +/-K55). Analyses of the simian T-cell lymphotropic virus type 3 (STLV-3)/CTO-604 complete proviral sequence (8,919 bp) indicated that this novel strain was highly divergent from HTLV-1 (60% nucleotide similarity), HTLV-2 (62%), or STLV-2 (62%) prototypes. It was, however, related to STLV-3/PH-969 (87%), a divergent STLV strain previously isolated from an Eritrean baboon. The STLV-3/CTO-604 sequence possesses the major open reading frames corresponding to the structural, enzymatic, and regulatory proteins. However, its long terminal repeat is shorter, with only two 21-bp repeats. Furthermore, as demonstrated by reverse transcriptase PCR, this new STLV exhibits significant differences from STLV-3/PH-969 at the mRNA splice junction position level. In all phylogenetic analyses, STLV-3/CTO-604 and STLV-3/PH-969 clustered in a highly supported single clade, indicating an evolutionary lineage independent from primate T-lymphotropic virus type 1 (PTLV-1) and PTLV-2. Nevertheless, the nucleotide divergence between STLV-3/PH-969 and STLV-3/CTO-604 is equivalent to or higher than the divergence observed between the different HTLV-1 or HTLV-2 subtypes. Thus, the STLV-3/CTO-604 strain can be considered the prototype of a second subtype in the PTLV-3 type. The presence of two related viruses in evolutionarily distantly related African monkeys species, living in two opposite ecosystems (rain forest versus desert), reinforces the possible African origin of PTLV and opens new avenues regarding the search for a possible human counterpart of these viruses in individuals exhibiting such HTLV-2-like seroreactivities.

Genetic polymorphism of human herpesvirus-7 among human populations.

The analysis of three human herpesvirus-7 (HHV-7) genes encoding phosphoprotein p100, glycoprotein B and major capsid protein respectively had previously shown the existence of distinct gene alleles, leading to the concept of HHV-7 variants. We have analysed the distribution of HHV-7 variants among 297 distinct subjects who belonged to different human populations from Africa, Asia, Europe and America. Two variants, designated Co1 and Co2, were found in 52% and 20% of studied subjects. Ten other variants, designated Co3-Co12, were less frequent and classified into two groups related to Co1 and Co2 respectively. While the former group was ubiquitous and the most frequent in Africa and Asia, the latter one was predominantly found in European and Mongol populations. Despite the high stability of the HHV-7 genome, a few nucleotide substitutions at precise positions define distinct variants which, to some extent, behave as markers of human populations.