Philippe Mauclère

Identification of a new human immunodeficiency virus type 1 distinct from group M and group O

A highly divergent HIV-1 isolate, designated YBF 30, was obtained in 1995 from a 40-year-old Cameroonian woman with AIDS. Depending on the genes studied, phylogenetic analysis showed that YBF30 branched either with SIVcpz-gab or between SIVcpz-gab and HIV-1 group M. The structural genes and tat, vpr, and nef of YBF30 are approximately equidistant from those of HIV-1 group M and SIVcpz-gab. In contrast, vif and rev are closer to HIV-1 group M, and vpu is highly divergent. Using a YBF30 V3 loop peptide enzyme immunoassay, we screened 700 HIV-1-positive sera collected in Cameroon; three reacted strongly with the YBF30 peptides and one was confirmed as being related to YBF30 by genetic analysis of a pol fragment. YBF30 is as distinct from SIVcpz-gab as it is from HIV-1 group M and can thus be considered as the prototype strain of a new human immunodeficiency virus group.

Human herpesvirus 8 primary infection occurs during childhood in Cameroon, Central Africa

While in the United States and northern Europe, human herpesvirus 8 (HHV‐8) appears to be mainly sexually transmitted with primary infection occurring in adulthood, the modes of transmission remain unknown in East and Central Africa, where Kaposis sarcoma (KS) is a long‐standing endemic disease, occurring not only in adults but also in children. The aim of our present study was to determine the prevalence of HHV‐8 infection in children from Yaoundé, Cameroon, Central Africa. Specific antibodies directed against both latent and lytic HHV‐8 antigens were detected and titrated, with an immunofluorescence assay using the KS‐1 cell line, in the plasma of 258 children and adolescents, of 32 mother and child pairs and of 189 pregnant women. Two different HHV‐8 DNA‐specific sequences were searched in the buffy coat by PCR assays. The overall HHV‐8 seroprevalence was 27.5% among these children and adolescents. In newborns, seroprevalence reached 46%, reflecting passive transmission of maternal IgG. This was followed by a marked drop. Then, beginning around 4 years of age, a regular increase of HHV‐8 antibodies took place, reaching 39% in the 12‐ to 14‐year age group and 48% above 15 years, a rate similar (54.5%) to that observed in pregnant women. PCR detection of HHV‐8 sequences was negative in seronegative children and positive in the buffy coat in 17% of HHV‐8‐seropositive children, reflecting a low viral load in the peripheral blood. Our results establish that in Central Africa HHV‐8 infection takes place during childhood by casual routes, in contrast to the sexual transmission observed in adults in northern Europe and the United States. We hypothesize that the lymphadenopathic form of KS seen in African children is related to an early and massive infection by HHV‐8 in susceptible individuals. Int. J. Cancer 81:189–192, 1999.

env Sequences of Simian Immunodeficiency Viruses from Chimpanzees in Cameroon Are Strongly Related to Those of Human Immunodeficiency Virus Group N from the Same Geographic Area

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) group N from Cameroon is phylogenetically close, in env, to the simian immunodeficiency virus (SIV) cpz-gab from Gabon and SIVcpz-US of unknown geographic origin. We screened 29 wild-born Cameroonian chimpanzees and found that three (Cam3, Cam4, and Cam5) were positive for HIV-1 by Western blotting. Mitochondrial DNA sequence analysis demonstrated that Cam3 and Cam5 belonged to Pan troglodytes troglodytes and that Cam4 belonged to P. t. vellerosus. Genetic analyses of the viruses together with serological data demonstrated that at least one of the two P. t. troglodytes chimpanzees (Cam5) was infected in the wild, and revealed a horizontal transmission between Cam3 and Cam4. These data confirm that P. t. troglodytes is a natural host for HIV-1-related viruses. Furthermore, they show that SIVcpz can be transmitted in captivity, from one chimpanzee subspecies to another. All three SIVcpz-cam viruses clustered with HIV-1 N inenv. The full Cam3 SIVcpz genome sequence showed a very close phylogenetic relationship with SIVcpz-US, a virus identified in aP. t. troglodytes chimpanzee captured nearly 40 years earlier. Like SIVcpz-US, SIVcpz-cam3 was closely related to HIV-1 N inenv, but not in pol, supporting the hypothesis that HIV-1 N results from a recombination event. SIVcpz from chimpanzees born in the wild in Cameroon are thus strongly related inenv to HIV-1 N from Cameroon, demonstrating the geographic coincidence of these human and simian viruses and providing a further strong argument in favor of the origin of HIV-1 being in chimpanzees.

Cell-to-Cell Contact Results in a Selective Translocation of Maternal Human Immunodeficiency Virus Type 1 Quasispecies across a Trophoblastic Barrier by both Transcytosis and Infection

ABSTRACT Mother-to-child transmission can occur in utero, mainly intrapartum and postpartum in case of breastfeeding. In utero transmission is highly restricted and results in selection of viral variant from the mother to the child. We have developed an in vitro system that mimics the interaction between viruses, infected cells present in maternal blood, and the trophoblast, the first barrier protecting the fetus. Trophoblastic BeWo cells were grown as a tight polarized monolayer in a two-chamber system. Cell-free virions applied to the apical pole neither crossed the barrier nor productively infected BeWo cells. In contrast, apical contact with human immunodeficiency virus (HIV)-infected peripheral blood mononuclear cells (PBMCs) resulted in transcytosis of infectious virus across the trophoblastic monolayer and in productive infection correlating with the fusion of HIV-infected PBMCs with trophoblasts. We showed that viral variants are selected during these two steps and that in one case of in utero transmission, the predominant maternal viral variant characterized after transcytosis was phylogenetically indistinguishable from the predominant childs virus. Hence, the first steps of transmission of HIV-1 in utero appear to involve the interaction between HIV type 1-infected cells and the trophoblastic layer, resulting in the passage of infectious HIV by transcytosis and by fusion/infection, both leading to a selection of virus quasispecies.

Simian Foamy Virus Transmission from Apes to Humans, Rural Cameroon

Bites from apes efficiently transmit the foamy virus to humans in natural settings in central Africa.

KSHV-like herpesviruses in chimps and gorillas.

Among the herpesviruses, KSHV (Kaposis-sarcoma-associated herpesvirus) is the human prototype of the rhadinovirus genus. Rhadinoviruses (or γ2-herpesviruses) are found in several animal species, including New and Old World monkeys, but not in the great apes. Here we describe the detection and sequencing of a polymerase gene fragment from three new rhadinoviruses discovered in chimpanzees and in a gorilla, which are more closely related to KSHV than to any other virus of this genus described so far. Our results indicate that the great apes from central Africa could provide a reservoir of new γ2-herpesviruses that are potentially transmissible to humans.

Selection of Maternal Human Immunodeficiency Virus Type 1 Variants in Human Placenta

To determine the mechanisms by which human immunodeficiency virus type 1 (HIV-1) crosses the placenta into the fetal blood, 12 matched samples of serial maternal blood, term placentas, and infant blood obtained from a cohort of pregnant women in Cameroon identified as predominantly infected by subtype A viruses were studied. HIV-1 env sequences were detected by polymerase chain reaction (PCR) in both chorionic villi and enriched trophoblastic cells of all 12 placentas but at variable rates of detection. Heteroduplex mobility assay analysis showed the presence of multiple HIV-1 env quasispecies in sequential maternal peripheral blood mononuclear cell samples, but only a small number of env variants were found in chorionic villi and enriched trophoblastic cells. These data indicate that HIV-1 env sequences are always present in term placentas of seropositive women, contrasting with the low frequency at which infection is diagnosed by PCR in neonates with tat, gag, and env primers. Maternal HIV-1 variants appear to undergo a strong negative selection by different cell populations within the placental villi.

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

BackgroundMalaria 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.MethodsWe 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.ResultsWe 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.ConclusionsThe 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.

Demographic, Ethnic, and Geographic Differences between Human T Cell Lymphotropic Virus (HTLV) Type I-Seropositive Carriers and Persons with HTLV-I Gag-Indeterminate Western Blots in Central Africa

Using stringent Western blot (WB) criteria, human T cell lymphotropic virus (HTLV) type I seroprevalence among 3783 persons from representative rural populations of Cameroon averaged 1.1% and was higher in females (1.5%) and in Pygmies (2.0%), increasing with age. Furthermore, an HTLV-I Gag-indeterminate WB profile (HGIP), exhibiting strong reactivities to p19, p26, p28, p32, p36, and pr 53 but lacking both p24 and env reactivity, was observed in 1.6% of the same populations. The prevalence of the HGIP was similar between males and females, did not increase with age, and appeared to cluster in tropical forests of southern Cameroon, especially among Pygmies (reaching 4%). These contrasting epidemiologic features, together with the lack of detection by polymerase chain reaction of HTLV-I sequences in the peripheral blood mononuclear cells of the persons with HGIP, strongly suggest that such a WB profile does not appear to reflect an HTLV-I-related viral infection but possibly an environmental (viral or parasitic) factor endemic in tropical rain forest areas.

Detection and genetic polymorphism of human herpes virus type 8 in endemic or epidemic Kaposi's sarcoma from West and Central Africa, and South America.

Kaposis‐sarcoma‐associated herpesvirus(KSHV)/human‐herpes‐virus‐8(HHV‐8) sequences originally detected in AIDS‐associated Kaposis sarcoma have been found in almost every KS tested, whether endemic, classic, iatrogenic or epidemic. Most of the studies on African KS involved East African patients. We report herewith the study of 17 African or Guyanan KS patients, 3 with epidemic KS (EKS) from Central African Republic, 3 from Senegal (2 EKS and 1 endemic KS), 3 EKS from Cameroon and 8 from French Guiana (3 EKS and 5 endemic KS). Serum‐specific antibodies directed against latent and/or lytic HHV‐8 antigens were present in 16 of them (94%), detected either by immunofluorescence assay and/or by immunoperoxidase. Polymerase chain reaction (PCR), using specific primers for HHV‐8 ORF26 (233 bp) and ORF75 (601 bp), was carried out on DNA extracted from KS cutaneous biopsies, clinically uninvolved skin biopsies and peripheral‐blood mononuclear cells (PBMC). HHV‐8 DNA was detected in 16 out of 16 (100%) KS biopsies, regardless of their origin or clinico‐pathological sub‐type, in 7 out of 15 (47%) normal skin samples and 7 out of 16 (44%) PBMC. Comparative PCR, carried out in 7 patients, regularly found a much higher viral load in KS biopsies than in autologous normal skin and PBMC samples. Sequencing of fragments of the ORF26 and of the ORF75 demonstrated that the 16 HHV‐8 strains were of the A, B or C sub‐type. Furthermore, sequences of the entire ORF K1 of 4 strains showed that these HHV‐8 strains of African origin were of the A5 or the B sub‐type. Int. J. Cancer 85:166–170, 2000. ©2000 Wiley‐Liss, Inc.