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Diarrheal diseases are a major cause of morbidity and mortality in infants and young children, particularly in sub-Saharan countries. In Gabon, there are few data on the prevalence of diarrheal pathogens in children. The aim of this study was to assess the prevalence of diarrheal pathogens in children with diarrhea in southeastern Gabon. Stool samples (n = 284) from Gabonese children 0 to 15 years of age with acute diarrhea were analyzed using polymerase chain reaction targeting 17 diarrheal pathogens. At least one pathogen was detected in 75.7% of samples (n = 215). Coinfection with multiple pathogens was observed in 44.7% of patients (n = 127). Diarrheagenic Escherichia coli was the most commonly detected pathogen (30.6%, n = 87), followed by adenovirus (26.4%, n = 75), rotavirus (16.9%, n = 48), Shigella sp. (16.5%, n = 47), Giardia duodenalis (14.4%, n = 41), norovirus GII (7.0%, n = 20), sapovirus (5.6%, n = 16), Salmonella enterica (4.9%, n = 14), astrovirus (4.6%, n = 13), Campylobacter jejuni/coli (4.6%, n = 13), bocavirus (2.8%, n = 8), and norovirus GI (2.8%, n = 8). Our study provides useful information on the possible causes of diarrheal diseases affecting children in southeastern Gabon. A similar study with a control group of healthy children is needed to assess the burden of the disease attributed to each pathogen.

Background: In Central Africa, it is difficult to fight against antibiotic resistance, because of a lack of data and information on bacterial resistance, due to the low number of studies carried out in the field. To fill this gap, we carried out a systematic review of the various studies, and devise a molecular epidemiology of antimicrobial resistance from humans, animals and the environmental samples.Method: A systematic search of all publications from 2005 to 2020 on bacterial resistance in Central Africa was performed on Pubmed, Google scholar and African journals online. All circulating resistance genes, prevalence and genetic carriers of these resistances were collected. The study area was limited to the 9 countries of Central Africa. Results: Five hundred seventeen studies were identified through a literature search, and sixty studies carried out in 8 countries were included. Among all articles included, 43 articles were from human. Our study revealed not only the circulation of beta-lactamase and carbapenemase genes, but also several other types of resistance genes. To finish, we noticed that some studies reported mobile genetic elements such as integrons, transposons, plasmids, or chromosomes.Conclusion: The scarcity of data poses difficulties in the implementation of effective strategies in the fight against antibiotic resistance, which requires a health policy in a "One Health" approach.

Yann Mouanga Ndzime,1,2 Richard Onanga,1 Roland Fabrice Kassa Kassa,1 Michelle Bignoumba,1 Pierre Philippe Mbehang Nguema,1,3 Amahani Gafou,1 Roméo Wenceslas Lendamba,1 Kelly Mbombe Moghoa,1 Cyrille Bisseye2 1Unité de Recherche et d’Analyses Médicales, Laboratoire de Bactériologie, Centre Interdisciplinaire de Recherches Médicales de Franceville, Franceville, BP 769, Gabon; 2Laboratoire de Biologie Moléculaire et Cellulaire (LABMC), Université des Sciences et Techniques de Masuku, Franceville, BP 943, Gabon; 3Institut de Recherche en Ecologie Tropicale, Centre National de la Recherche Scientifique et Technologique (CENAREST), Libreville, BP 13354, GabonCorrespondence: Yann Mouanga Ndzime Tel +24177206217 Email yann_mouangandzime@yahoo.frIntroduction: Urinary tract infection is one of the major causes of consultation, microbiologic exploration, intensive use of antibiotics worldwide, and the second leading cause of clinical consultation in community practice. Many bacteria play a role in the urinary tract infections etiology, including Enterobacteriaceae such as Escherichia coli (E. coli) and Klebsiella spp.Objective: The study’s main objective was to examine the epidemiology of E. coli and Klebsiella pneumoniae (K. pneumoniae) uropathogenic strains resistant to antibiotics in Franceville.Methodology: The study was carried out between January 2018 and June 2019 in Franceville South-East Gabon. We examined a total of 1086 cytobacteriological urine samples. The identification of E. coli and K. pneumoniae strains was carried out using the Vitek-2 compact automated system and the antibiogram with the disk diffusion method according to the European Committee on Antimicrobial Susceptibility Testing recommendations.Results: The prevalence of urinary tract infections was 29.2% (317/1086), of which 25.1% and 4.1% were mono-infections and co-infections, respectively. The prevalence of UTIs with E. coli was 28.7% (91/317) with a predominance of isolation in women. K. pneumoniae was responsible for 16.2% (61/317) of UTIs. E. coli and K. pneumoniae Uropathogenic strains showed resistance to beta-lactams, quinolones and cotrimoxazole, whereas Nitrofurantoin, Amikacin, Imipenem and Ertapenem were the most active antibiotics against E. coli and K. pneumoniae uropathogenic strains.Conclusion: This study showed a high prevalence of urinary tract infections with a major implication of E.coli and K. pneumoniae strains. E. coli and K. pneumoniae presented high frequency of resistance to antibiotics, highlighting the need to adapt their use accordingly at the local level.Keywords: urinary tract infection, antibiotic resistance, E. coli, K. pneumoniae

Background: The increasing phenomenon of bacterial resistance to antibiotics is a real public health problem. The main causes are poor management of hygiene and water quality, but also the use of antibiotics without precaution. The objective of this study was to isolate and determine the antibiotic resistance profile of the different bacteria found in the main hospitals and bacteriology laboratories in Gabon. Methods: 6034 samples were taken from hospitals in seven main cities of Gabon, and analyzed according to the usual techniques. The pathogenic strains were identified by Matrix-Assisted Laser Desorption Ionization-Time Of Flight Mass Spectrometry. Antimicrobial susceptibility testing was performed by the agar disc diffusion method, according to the Antibiogram Committee of the French Society for Microbiology guidelines. Results: 974 pathogenic bacterial strains were found, including 890/974 (91.4%) Gram-negative bacilli. The systematic antimicrobial susceptibility testings identified 160/974 (16.4%) multi-resistant strains. Escherichia coli was the most represented species. 12.5% - 25% of Escherichia coli, Klebsiella pneumoniae, Enterobacter cloacae, and Citrobacter sedlakii strains were resistant to amoxicillin + clavulanic acid, third and fourth generation cephalosporins. Aminoglycoside resistance rates of 8.5% - 19% were also noted. 4.5% to 25% of the bacteria found were resistant to quinolones and cotrimoxazole. Resistance rates to carbapenems ranged from 1% to 10.5%. 16% of Staphylococcus aureus were methicillin-resistant (MRSA). Rates of extended spectrum beta-lactamase-producing enterobacteriaceae (ESBL-PE) ranged from 2.5% to 25%. Conclusion: This study showed an increasing evolution of bacterial resistance to antibiotics that are spreading throughout Gabon. This constitutes a threat to the health of Gabonese population.

The purpose of this study was to provide contextual information on indigenous food’s technologies and safety from Gabon. The strategic focus being to promote local food with enhanced nutritional value and improved safety. An investigation and monitoring were carried out to elucidate their process flow diagrams and to identify safety failures. Samples were taken for microbiological analysis using conventional culture-based techniques. Detection and identification of Salmonella in samples were confirmed using PCR based method by targeting invasion plasmid antigen B (IpaB) gene. The investigation shows that women play a protagonist role in the technical know-how of Gabonese indigenous foods in a context that is evolving towards the disappearance of this knowledge. The food production process remains archaic, which makes the environment impact on food safety. Indeed, the proximity of food manufacturing environment to animals, waste, or latrines coupled with the lack of hygiene and manufacturing practices affect the quality of these foods. This is reflected in our study's microbiological results, namely, Aerobic Mesophilic Bacteria ranged from 3.53 to 11.96 log CFU/g and indicators of fecal contaminations of up to 8.21 log CFU/g. Salmonella is detected in 18.69% of samples. The presence of these bacteria is a risk for consumer health. Although some of these foods can be considered as a fermented food, the producers should be further educated and encouraged to take preventive measures to ensure the quality of these food products. A much more subtle approach based on microbial ecology of these foods should be explored for better exploitation.

Data collection and monitoring of carbapenemase-producing (CP) Gram-negative bacteria (GNB) are often limited. This study determined CP-GNB prevalence in Gabon and the genetic origins of the resistance genes. From January 2016 to March 2018, 869 clinically significant GNB isolates from inpatients and outpatients, and 19 fecal samples (inpatients) were analyzed in the main hospitals of Gabon. Fecal samples were screened using ChromID® CARBA SMART selective chromogenic medium biplates. Species were identified by matrix-assisted laser desorption ionization-time of flight mass spectrometry. Antibiotic susceptibility was tested using the disk diffusion method on Müller-Hinton agar, and resistance genes were assessed by multiplex polymerase chain reaction and sequencing. Overall, 1.61% of clinical isolates (14 of 869) and 5.26% of fecal samples (1 of 19) were CP-GNB. The CP-GNB rate was higher among inpatients (2.98%) than outpatients (0.33%), in intensive care units (28.57%, 4 of 14), and in urine samples (35.71%, 5 of 14). The most common CP-GNB were Klebsiella pneumoniae (53.33%) and Acinetobacter baumannii (26.67%). blaOXA-48 was the predominant carbapenemase-encoding gene (40%), followed by blaNDM-5 (33.33%). The A. baumannii multilocus sequence types ST2 and ST78, Enterobacter cloacae ST78, Escherichia coli ST2, and K. pneumonia ST48 and ST147 were found. These data indicate that CP bacteria are present in clinical and carriage samples. Preventive measures are needed to avoid the spread of resistance genes.

Discomfort in women of childbearing age associated with vaginal infections, namely Bacterial Vaginosis (BV), Aerobic Vaginitis (AV), VulVovaginal Candidiasis (VVC), and Trichomoniasis (TV), represent a serious and ongoing gynecological complication throughout the world. This study aimed to investigate the etiologies of vaginal infections among outpatients in south-eastern Gabon. A cross-sectional study was designed using participants referred directly by their treating doctor for a vaginal swab. Socio-demographic data were collected using a structured questionnaire. Microscopic examinations were used for TV and BV diagnostic. All vaginal swabs were cultured for AV and VVC isolates using standard microbiology methods. A total of 573 women of reproductive age participated in the study. The most common identified vaginal infections were BV (62.8%) and AV (51.1%) followed by VVC (34.1%). No significant difference was observed for each etiology compared to socio-demographic data. Streptococcus B (23.9%), Staphyloccocus aureus (17.7%), Klebsiella spp. (11.6%), and E. coli (5.8%) were the bacteria most associated with AV. A high incidence of Non-C. Albicans Candida (NCAC) strains causing vulvovaginitis were found. The prevalence of TV (2.1%) was low. Mixed infections had been common among participants. No association was found with TV and other vaginal infections, unlike others studies. The present study identified BV 228 (83.5%) and AV 227 (83.2%) as the main cause of mixed infections. The mixed infection AV-BV 113 (41.4%) was the most represented. Also, that simultaneous AV-BV-VVC represented 69 (25.3%) of mixed infections. Molecular analyses would be needed to identify the key species commonly associated with these vaginal infections.

The emergence of antibiotic resistance is a major concern around the world. The objective of this study was to investigate the antibiotics used in livestock and their impact on resistance in

Data on the prevalence of antibiotic resistance in Enterobacteriaceae in African wildlife are still relatively limited. The aim of this study was to estimate the prevalence of phenotypic intrinsic and acquired antimicrobial resistance of enterobacteria from several species of terrestrial wild mammals in national parks of Gabon. Colony culture and isolation were done using MacConkey agar. Isolates were identified using the VITEK 2 and MALDI-TOF methods. Antibiotic susceptibility was analysed and interpreted according to the European Committee on Antimicrobial Susceptibility Testing guidelines. The preliminary test for ESBL-producing Enterobacteriaceae was performed by replicating enterobacterial colonies on MacConkey agar supplemented with 2 mg/L cefotaxime (MCA+CTX). Extended-spectrum beta-lactamase (ESBL) production was confirmed with the double-disc synergy test (DDST). The inhibition zone diameters were read with SirScan. Among the 130 bacterial colonies isolated from 125 fecal samples, 90 enterobacterial isolates were identified. Escherichia coli (61%) was the most prevalent, followed by Enterobacter cloacae (8%), Proteus mirabilis (8%), Klebsiella variicola (7%), Klebsiella aerogenes (7%), Klebsiella oxytoca (4%), Citrobacter freundii (3%), Klebsiella pneumoniae (1%) and Serratia marcescens (1%). Acquired resistance was carried by E. coli (11% of all E. coli isolates) and E. cloacae (3% of all E. cloacae) isolates, while intrinsic resistance was detected in all the other resistant isolates (n = 31); K. variicola, K. oxytoca, K. pneumoniae, E. cloacae, K. aerogenes, S. marcescens and P. mirabilis). Our data show that most strains isolated in protected areas in Gabon are wild type isolates and carry intrinsic resistance rather than acquired resistance.

Introduction Urinary tract infection is one of the major causes of consultation, microbiologic exploration, intensive use of antibiotics worldwide, and the second leading cause of clinical consultation in community practice. Many bacteria play a role in the urinary tract infections etiology, including Enterobacteriaceae such as Escherichia coli (E. coli) and Klebsiella spp. Objective The study’s main objective was to examine the epidemiology of E. coli and Klebsiella pneumoniae (K. pneumoniae) uropathogenic strains resistant to antibiotics in Franceville. Methodology The study was carried out between January 2018 and June 2019 in Franceville South-East Gabon. We examined a total of 1086 cytobacteriological urine samples. The identification of E. coli and K. pneumoniae strains was carried out using the Vitek-2 compact automated system and the antibiogram with the disk diffusion method according to the European Committee on Antimicrobial Susceptibility Testing recommendations. Results The prevalence of urinary tract infections was 29.2% (317/1086), of which 25.1% and 4.1% were mono-infections and co-infections, respectively. The prevalence of UTIs with E. coli was 28.7% (91/317) with a predominance of isolation in women. K. pneumoniae was responsible for 16.2% (61/317) of UTIs. E. coli and K. pneumoniae Uropathogenic strains showed resistance to beta-lactams, quinolones and cotrimoxazole, whereas Nitrofurantoin, Amikacin, Imipenem and Ertapenem were the most active antibiotics against E. coli and K. pneumoniae uropathogenic strains. Conclusion This study showed a high prevalence of urinary tract infections with a major implication of E.coli and K. pneumoniae strains. E. coli and K. pneumoniae presented high frequency of resistance to antibiotics, highlighting the need to adapt their use accordingly at the local level.

Mycoplasma hominis and Ureaplasma urealyticum are microorganisms involved in many pathologies and intrauterine infections. Vaginal wall swabs were taken from 278 women for mycoplasma detection and to study the antimicrobial susceptibility using the Mycoplasma IST2 Kit (bioMerieux). We were able to document in 278 women enrolled in the study, 64.7% have infections caused by U. urealyticum, 22.7% by M. hominis, and 19.4 % of coinfections involving both germs. Such infections were observed in age groups between 18 and 42 years. Other socio-demographic characteristics studies have been conducted, which allowed to document that single women were the majority population with 68.7% against 16.5% who were living in couple. In response to our questionnaire, 131 single women enrolled in the study never protected themselves during sexual intercourse compared with 52.9% who reported using at least condom. A total of 260 (93.5%) of women reported having only one partner versus 6.5% having more. The study of strains susceptibility to antibiotics revealed a resistance of approximately 80% for macrolides and 100% for fluoroquinolones. All our isolated strains had a sensitivity of about 90% for Pristinamycin and 70% for Josamycin. This study shows that carriage of mycoplasma infection is high in female population in Franceville and vicinities, what should be an element of cautious use of antibiotic during probabilistic therapy treatment of mycoplasma.

In Gabon, terrestrial mammals of protected areas have been identified as a possible source of antibiotic-resistant bacteria. Some studies on antibiotic resistance in bats have already been carried out. The main goal of our study was to detect extended-spectrum beta-lactamases (ESBLs) that are produced by enterobacteria from bats in the Makokou region in Gabon. Sixty-eight fecal samples were obtained from 68 bats caught in the forests located 1 km from the little town of Makokou. After culture and isolation, 66 Gram-negative bacterial colonies were obtained. The double-disk diffusion test confirmed the presence of ESBLs in six (20.69%) Escherichia coli isolates, four (13.79%) Klebsiella pneumoniae isolates, and one (3.45%) Enterobacter cloacae isolate. The analysis based on the nucleotide sequences of the ESBL resistance genes showed that all cefotaximase-Munichs (CTX-Ms) were CTX-M-15 and that all sulfhydryl variables (SHVs) were SHV-11: 41.67% CTX-M-15-producing E. coli, 16.67% CTX-M-15+SHV-11-producing E. coli, 8.33% CTX-M-15-producing K. pneumoniae, 25% CTX-M-15+SHV-11-producing K. pneumoniae, and 8.33% CTX-M-15-produced E. cloacae. This study shows for the first time the presence of multiresistant ESBL-producing enterobacteria in fruit bats in Makokou.

Antibiotic resistance occurs in the environment by multiplication and the spread of multidrug-resistant bacteria that would be due to an improper and incorrect use of antibiotics in human and veterinary medicine. The aim of this study was to establish the prevalence of E.coli producing Extended-Spectrum beta-Lactamase (ESBL) antibiotics from rats and gregarious animals in a semirural area of Gabon and to evaluate the origin of a resistance distribution in the environment from animal feces. The bacterial culture was carried out, and the identification of E. coli strains on a specific medium and the antibiotic susceptibility tests allowed establishing the prevalence. Characterization of resistance genes was performed by gene amplification after DNA extraction. On 161 feces collected in rats, 32 strains were isolated, and 11 strains of E. coli produced ESBL with a prevalence of 34.37%. Molecular tests showed that CTX-M genes 214 bp were identified in rats. The presence of CTX-M genes could have a human origin. So, the rats can carry ESBL-producing Enterobacteriaceae which poses a risk to human health and pets in this region of Gabon.

The last decades, various research approaches have been undertaken worldwide for drug discoveries. Our study aimed to investigate medicinal plants of the Lekedi Park through a zoopharmacological and ethnopharmacological surveys on mandrills and on human population respectively from the Department of Lekoko.Data on feeding behaviour were collected on 57 mandrills, from Lekedi Park, using a 5-min focal sampling method for 17 months. The ethnopharmacological uses were carried out on the human population using semi-structured questionnaires and scientific databases. Data were evaluated statistically by using the index of Use value (UV) and informant consensus factor (Fic).The results showed that studied mandrills used about 147 plant species belonging to 48 botanical families. The Rubiaceae and Euphorbiaceae families were the most representative in the mandrill diet. Among plant organs eaten, some organs of plants such as bark or roots rich in non-nutritional compounds were occasionally used by mandrills, suggesting the involvement of a self-medication behavior in mandrill. Also, it appears that the plant selection would be mainly due to the availability, protein and sugar contents. Ethnopharmacological surveys show that among the 147 consumed by mandrills, 33% were used for medicinal purposes only, 41% as food and 11% were used as food and as medicine. The informant consensus factor values indicate that the medicinal plants are effective in treating certain diseases.Thus, the study of mandrill diets behaviour would be a potential approach for the drugs discovery against bacterial and parasitic affections.

The majority of patients with acute febrile jaundice (>95%) identified through a yellow fever surveillance program in the Democratic Republic of Congo (DRC) test negative for antibodies against yellow fever virus. However, no etiological investigation has ever been carried out on these patients. Here, we tested for hepatitis A (HAV), hepatitis B (HBV), hepatitis C (HCV), hepatitis D (HDV), and hepatitis E (HEV) viruses, all of which can cause acute febrile jaundice, in patients included in the yellow fever surveillance program in the DRC. On a total of 498 serum samples collected from suspected cases of yellow fever from January 2003 to January 2012, enzyme-linked immunosorbent assay (ELISA) techniques were used to screen for antibodies against HAV (IgM) and HEV (IgM) and for antigens and antibodies against HBV (HBsAg and anti-hepatitis B core protein [HBc] IgM, respectively), HCV, and HDV. Viral loads and genotypes were determined for HBV and HVD. Viral hepatitis serological markers were diagnosed in 218 (43.7%) patients. The seroprevalences were 16.7% for HAV, 24.6% for HBV, 2.3% for HCV, and 10.4% for HEV, and 26.1% of HBV-positive patients were also infected with HDV. Median viral loads were 4.19 × 105 IU/ml for HBV (range, 769 to 9.82 × 109 IU/ml) and 1.4 × 106 IU/ml for HDV (range, 3.1 × 102 to 2.9 × 108 IU/ml). Genotypes A, E, and D of HBV and genotype 1 of HDV were detected. These high hepatitis prevalence rates highlight the necessity to include screening for hepatitis viruses in the yellow fever surveillance program in the DRC.

Wild animal meat represents an important source of protein for many people in central Africa. Also known as bushmeat, this meat commodity is derived from wild animals hunted under uncontrolled conditions, transported to distant markets under rudimentary or no hygienic methods, and often eviscerated >24 hr after death. Considering the plausible role of wildlife as a reservoir for bacterial zoonotic pathogens, bushmeat may be an important public health risk in Central Africa. This cross-sectional survey served to evaluate the presence of Campylobacter, Salmonella, and Shigella in the muscle tissue of 128 wild animal carcasses from several hunted wildlife species (guenons [Cercopithecus spp.], collared mangabeys [Cercocebus torquatus], gray-cheeked mangabeys [Lophocebus albigena], African crested porcupines [Atherurus africanus], duikers [Cephalophus spp.], and red river hogs [Potamocherus porcus]) sold in two markets of Port-Gentil, Gabon, in July and August 2010. Salmonella was detected from one carcass; no Campylobacter or Shigella was detected. If Campylobacter and Shigella were present, the maximum expected prevalence was estimated at 6% and 1%, respectively. In light of such very low apparent muscle contamination levels, bushmeat likely does not represent a health risk per se with respect to Campylobacter, Salmonella, or Shigella. However, because carcass evisceration and skinning can take place within households prior to consumption, consumers should follow strict hygiene and food safety practices to avoid potential health hazards associated with the handling, preparation, or consumption of bushmeat.

Mandrills are the only nonhuman primate (NHP) naturally infected by two types of simian immunodeficiency virus (SIV): SIVmnd-1 and SIVmnd-2. We have already reported that the high SIVmnd-1 replication during primary infection contrasts with only transient changes in CD4 + and CD8 + cell counts. Since early virus-host interactions predict viral control and disease progression in human immunodeficiency virus-infected patients, we investigated the dynamics of SIVmnd-2 primary infection in mandrills to examine the impact on immune effectors in blood and lymph nodes (LNs). To avoid in vitro strain selection, all mandrills in this study received plasma from SIVmnd-2-infected mandrills. SIVmnd-2 plasma viremia peaked at 10 7 to 10 8 RNA copies/ml between days 7 and 10. This peak was followed in all four monkeys by a decline in virus replication, with a set point level of 10 5 to 10 6 RNA copies/ml at day 42 postinfection (p.i.). Viral DNA load in PBMC and LNs also peaked between days 7 and 10 (10 5 to 10 6 DNA copies/10 6 cells) and stabilized at 10 3 to 10 4 DNA copies/10 6 cells during the chronic phase. Anti-SIVmnd-2 antibodies were detected starting from days 28 to 32. A transitory decline of CD3 + CD4 + cells in the LNs occurred in animals with high peak VLs. CD4 + and CD8 + T-cell activation in blood and LNs was noted between days 5 and 17 p.i., surrounding the peak of viral replication. This was most significant in the LNs. Activation markers then returned to preinfection values despite continuous and active viral replication during the chronic infection. The dynamics of SIVmnd-2 infection in mandrills showed a pattern similar to that of SIVmnd-1 infection. This might be a general feature of nonpathogenic SIV natural African NHP models.

The mandrill (Mandrillus sphinx) has been shown to be infected with an STLV-1 closely related to HTLV-1. Two distinct STLV-1 subtypes (D and F) infect wild mandrills with high overall prevalence (27.0%) but are different with respect to their phylogenetic relationship and parallel to the mandrills' geographic range. The clustering of these new STLV-1mnd sequences with HTLV-1 subtype D and F suggests first, past simian-to-human transmissions in Central Africa and second, that species barriers are easier to cross over than geographic barriers.

Viral loads were investigated in SIVmnd-1 chronically infected mandrills and the results were compared with those previously observed in other nonpathogenic natural SIV infections. Four naturally and 11 experimentally SIVmnd-1-infected mandrills from a semi-free-ranging colony were studied during the chronic phase of infection. Four SIVmnd-1-infected wild mandrills were also included for comparison. Twelve uninfected mandrills were used as controls. Viral loads in all chronically infected mandrills ranged from 10 5 to 9 × 10 5 copies/ml and antibody titers ranged from 200 to 14,400 and 200 to 12,800 for anti-V3 and anti-gp36, respectively. There were no differences between groups of wild and captive mandrills. Both parameters were stable during the follow-up, and no clinical signs of immune suppression were observed. Chronic SIVmnd-1-infected mandrills presented slight increases in CD20 + and CD28 + /CD8 + cell counts, and a slight decrease in CD4 + /CD3 + cell counts. A slight CD4 + /CD3 + cell depletion was also observed in old uninfected controls. Similar to other nonpathogenic models of lentiviral infection, these results show a persistent high level of SIVmnd-1 replication during chronic infection of mandrills, with minimal effects on T cell subpopulations.

African nonhuman primates are natural hosts for simian immunodeficiency viruses (SIVs). To date, SIV infections have been detected in 20 distinct species (24). SIVs were shown to cluster in six major, approximately equidistant lineages (17, 53). Human immunodeficiency virus type 1 (HIV-1) and HIV-2 belong to two of these clusters and emerged most likely following zoonotic transmissions of, respectively, SIVcpz from chimpanzees and SIVsm from sooty mangabeys (14, 16, 21). The remaining clusters are formed by SIVs isolated from African green monkeys (AGMs), Syke's monkeys, l'hoest monkeys, and colobus monkeys (4, 17, 20, 27, 39, 60). The phylogeny of many SIVs resembles that of their host species, suggesting a coevolution (1, 21, 39). In contrast to these, some viruses (SIVrcm, SIVagm.sab, SIVmnd-2, and SIVdrl) cluster in different lineages according to the genomic region analyzed (15, 22, 31, 55). These viruses most likely result from recombination events in monkeys dually infected by SIVs of two distinct lineages (15, 22, 31, 55). Such dual infections suppose the existence of cross-species transmissions of SIV in nature. It has indeed been shown that wild patas monkeys and baboons can acquire SIVagm (7, 32, 61). It remains unclear if these two latter species are infected with species-specific SIVs (54). This was also questioned for mandrills (Mandrillus sphinx). The first SIVmnd strain (GB1), now defined as SIVmnd-1, was isolated 13 years ago from a wild-born mandrill (59). This virus was the only representative of the SIVmnd lineage until two Cercopithecinae viruses, from l'hoest (Cercopithecus l'hoesti l'hoesti) and sun-tailed monkeys (Cercopithecus l'hoesti solatus) were shown to cluster in the same lineage as SIVmnd GB1 (4, 29). As the genome of SIVmnd GB1 had the organization of Cercopithecus SIVs and not that of Papionini SIVs, and because the habitat of mandrills and sun-tailed monkeys overlaps in Gabon, it was suggested that SIVmnd GB1 represents a virus cross-transmitted from sun-tailed monkeys to mandrills, and the lineage was renamed the l'hoest lineage (4, 5). It was subsequently demonstrated that SIVmnd GB1-related viruses are commonly present in wild adult mandrills, indicating that the virus is capable, at least today, of efficiently spreading between animals of this species (55). Mandrills infected with SIVmnd-1 are separated by the Ogooue River from mandrills infected with SIVmnd type 2 (55). This latter virus has a genomic organization distinct from those of SIVmnd GB1 and SIVlhoest and identical to that of SIVs of other Papio monkeys, such as SIVsm and SIVdrl (15, 55). It is unknown why SIV infections are generally nonpathogenic in African nonhuman primates. SIVmnd-2 infections in mandrills have not been associated with signs of AIDS. SIVmnd-1 infection, which apparently results from SIV transmission from C. l'hoesti to mandrills, is also considered to be asymptomatic, although a possible exception has been reported (44). SIVlhoest, which is genetically close to SIVmnd-1 and is also associated with asymptomatic infection in its natural host, appears to induce AIDS in macaques (29). In both HIV-1-infected humans and SIVmac-infected macaques, it was shown that early virus-host interactions are predictive of the outcome of infection. Predictive markers are in particular gag-specific T-helper responses and viral load levels in the post-acute phase of infection (36, 50). In macaques, the steady-state level of plasma viremia 5 to 6 weeks after exposure to the virus is an excellent predictor of the subsequent disease course (28, 35, 42, 63). RNA levels in plasma measured early in HIV-1 infection are also highly predictive of subsequent rates of disease progression (36, 37, 43). However, although this observation is broadly acknowledged and used as the main indication for treating HIV-1-infected patients early in the course of the disease (10), little is still known about the driving mechanism(s) directing this phenomenon. Studies of the early events during nonpathogenic infections in natural host species can help to elucidate such mechanisms. So far, studies during the early phase of infection in African nonhuman primates are limited (58). Studies in SIVagm.sab92018-infected AGMs have revealed for the first time an extensive replication during the acute and post-acute phases (18). Many naturally infected AGMs analyzed during the chronic phase also show continuously high levels of viral RNA in plasma (9, 23). Moreover, virus load in the blood and lymph nodes (LN) of mangabeys during chronic infection is at levels equivalent to that in macaques and humans progressing to AIDS, despite the lack of clinical signs of AIDS (49). The absence of AIDS in these monkeys therefore seems to be paradoxical in the presence of such a high viral load. However, it is not clear whether the high viral replication observed is a general feature of nonpathogenic infections in natural host species (3, 23). Moreover, the precise dynamics of CD4+ and CD8+ cells during primary infection have not been reported so far. Our primary objective for the present study was to investigate the acute and post-acute phases of SIVmnd-1 infection in mandrills. SIVmnd-1 is thought to represent the result of an ancient cross-species transmission in the wild (4, 6), and we investigated whether it would represent an intermediate model between the pathogenic and nonpathogenic models of lentiviral infections. We analyzed viral dynamics and corroborated the virological study with the analyses of CD4+- and CD8+-T-cell changes over time in the blood and LN.

Since the first characterization of SIVsun (L14 strain) from a sun-tailed monkey (Cercopithecus solatus) in Gabon in 1999, no further information exists about the evolutionary history and geographic distribution of this lentivirus. Here, we report the full-length molecular characterization of a second SIVsun virus (SIVsunK08) naturally infecting a wild-caught sun-tailed monkey. The SIVsunK08 strain was most closely related to SIVsunL14 and clustered with members of the SIVmnd-1/SIVlhoest group. SIVsunK08 shared identical functional motifs in the LTR, Gag and Env proteins with SIVsunL14. Our data indicate that C. solatus is naturally infected with a monophyletic SIVsun strain.

The mandrill (Mandrillus sphinx) is naturally infected by two types of simian immunodeficiency virus (SIV): SIVmnd types 1 and 2. Both of these viruses cause long-term, non-progressive infections in their natural host despite high plasma viral loads. This study assessed the susceptibility of rhesus macaques to infection by these two types of SIVmnd and compared the virological and basic immunological characteristics of the resulting infections with those observed in natural infection in mandrills. Whilst both SIVmnd types induced similar levels of virus replication during acute infection in both mandrills and macaques, they produced a more pronounced CD4+ T-cell depletion in rhesus macaques that persisted longer during the initial stage of infection. Pro-inflammatory cytokine responses were also induced at higher levels in rhesus macaques early in the infection. During the chronic phase of infection in mandrills, which in this case was followed for up to 2 years after infection, high levels of chronic virus replication did not induce significant changes in CD4+ or CD8+ T-cell counts. In rhesus macaques, the overall chronic virus replication level was lower than in mandrills. At the end of the follow-up period, although the viral loads of SIVmnd-1 and SIVmnd-2 were relatively similar in rhesus macaques, only SIVmnd-1-infected rhesus macaques showed significant CD4+ T-cell depletion, in the context of higher levels of CD4+ and CD8+ T-cell activation, compared with SIVmnd-infected mandrills. The demonstration of the ability of both SIVmnd types to induce persistent infections in rhesus macaques calls for a careful assessment of the potential of these two viruses to emerge as new human pathogens.

Simian immunodeficiency virus (SIV) persistence in wild populations of African nonhuman primates (NHPs) may occur through horizontal and vertical transmission. However, the mechanism(s) and timing of the latter type of transmission have not been investigated to date. Here we present the first study of SIV transmissibility by breast-feeding in an African NHP host. Six mandrill dames were infected with plasma containing 300 50% tissue culture infective doses of SIVmnd-1 on the day after delivery. All female mandrills became infected, as demonstrated by both plasma viral loads (VLs) and anti-SIVmnd-1 seroconversion. Neither fever nor lymphadenopathy was observed. At the peak of SIVmnd-1 viral replication (days 7 to 10 postinoculation), plasma VLs were high (8 × 10 6 to 8 × 10 8 RNA copies/ml) and paralleled the high VLs in milk (4.7 × 10 4 to 5.6 × 10 5 RNA/ml). However, at the end of the breast-feeding period, after 6 months of follow-up, no sign of infection was observed for the offspring. Later on, during a 4-year follow-up examination, two of the offspring showed virological evidence of SIVmnd-1 infection. Both animals seroconverted at least 6 months after the interruption of lactation. In conclusion, despite extensive viral replication in mandrill mothers and high levels of free virus in milk, no SIVmnd-1 transmission was detectable at the time of breast-feeding or during the following months. Since we observed a markedly lower expression of CCR5 on the CD4 + T cells of young mandrills and African green monkeys than on those of adults, we propose that low levels of this viral coreceptor on CD4 + T cells may be involved in the lack of breast-feeding transmission in natural hosts of SIVs.

T cell activation levels in HIV infection are predictive of AIDS progression. We searched for the immunological correlates of protection against disease progression by studying the early stages of nonpathogenic SIV infection in African green monkeys (SIVagm). The African green monkeys (AGMs) displayed high peak viremias and a transient decline in levels of blood CD4(+) and CD8(+) T cells between days 5 and 17 after infection. A concomitant increase in levels of CD4(+)DR(+), CD8(+)DR(+), and CD8(+)CD28(-) cells was detected. After the third week, T cell activation returned to baseline levels, which suggested a protective downregulation of T cell activation. A very early (24 hours after infection) and strong induction of TGF-beta1 and FoxP3 expression was detected and correlated with increases in levels of CD4(+)CD25(+) and CD8(+)CD25(+) T cells. This was followed by a significant increase in levels of IL-10, whereas IFN-gamma gene upregulation was more transient, and levels of TNF-alpha and MIP-1alpha/beta transcripts did not increase in either blood or tissues. The profiles were significantly different during primary SIV infection in macaques (SIVmac); that is, there was a delayed increase in IL-10 levels accompanied by moderate and persistent increases in TGF-beta levels. Together, our data show that SIVagm infection is associated with an immediate antiinflammatory environment and suggest that TGF-beta may participate in the generation of Tregs, which may prevent an aberrant chronic T cell hyperactivation.

This study set out to characterize the features of experimental infection by simian immunodeficiency virus in mandrill (SIVmnd) (Mandrillus sphinx), cynomolgus macaque (Macaca fascicularis), rhesus macaque (Macaca mulatta), chimpanzee (Pan troglodytes), African green monkey (Cercopithecus pygerythrus), baboon (Papio cynocephalus) and human cells. Purified cells were exposed to a primary isolate of SIVmnd grown in the infected mandrill peripheral blood mononuclear cells, and viral p27 gag antigen was quantitated by antigen capture ELISA. Human cells have been found to be infected by SIVmnd. SIVmnd infection in cynomolgus macaque, rhesus macaque, baboon, mandrill and human cells were more effective than in vervet and chimpanzee cells. In addition, the lymphocytic cell lines SupT1, CEMx174 and Molt4 clone 8 were consistently infected by SIVmnd, whereas U937, a monocytic cell line, was not.

Mandrillus sphinx , a large primate living in Cameroon and Gabon and belonging to the Papionini tribe, was reported to be infected by a simian immunodeficiency virus (SIV) (SIVmndGB1) as early as 1988. Here, we have identified a second, highly divergent SIVmnd (designated SIVmnd-2). Genomic organization differs between the two viral types; SIVmnd-2 has the additional vpx gene, like other SIVs naturally infecting the Papionini tribe (SIVsm and SIVrcm) and in contrast to the other SIVmnd type (here designated SIVmnd-1), which is more closely related to SIVs infecting l'hoest ( Cercopithecus lhoesti lhoesti ) and sun-tailed ( Cercopithecus lhoesti solatus ) monkeys. Importantly, our epidemiological studies indicate a high prevalence of both types of SIVmnd; all 10 sexually mature wild-living monkeys and 3 out of 17 wild-born juveniles tested were infected. The geographic distribution of SIVmnd seems to be distinct for the two types: SIVmnd-1 viruses were exclusively identified in mandrills from central and southern Gabon, whereas SIVmnd-2 viruses were identified in monkeys from northern and western Gabon, as well as in Cameroon. SIVmnd-2 full-length sequence analysis, together with analysis of partial sequences from SIVmnd-1 and SIVmnd-2 from wild-born or wild-living mandrills, shows that the gag and pol regions of SIVmnd-2 are closest to those of SIVrcm, isolated from red-capped mangabeys ( Cercocebus torquatus ), while the env gene is closest to that of SIVmnd-1. pol and env sequence analyses of SIV from a related Papionini species, the drill ( Mandrillus leucophaeus ), shows a closer relationship of SIVdrl to SIVmnd-2 than to SIVmnd-1. Epidemiological surveys of human immunodeficiency virus revealed a case in Cameroon of a human infected by a virus serologically related to SIVmnd, raising the possibility that mandrills represent a viral reservoir for humans similar to sooty mangabeys in Western Africa and chimpanzees in Central Africa.

A seroprevalence survey was conducted for simian immunodeficiency virus (SIV) antibody in household pet monkeys in Gabon. Twenty-nine monkeys representing seven species were analyzed. By using human immunodeficiency virus type 2 (HIV-2)/SIVsm, SIVmnd, and SIVagm antigens, one red-capped mangabey (RCM) ( Cercocebus torquatus torquatus ) was identified as harboring SIV-cross-reactive antibodies. A virus isolate, termed SIVrcm, was subsequently established from this seropositive RCM by cocultivation of its peripheral blood mononuclear cells (PBMC) with PBMC from seronegative humans or RCMs. SIVrcm was also isolated by cocultivation of CD8-depleted RCM PBMC with Molt 4 clone 8 cells but not with CEMx174 cells. The lack of growth in CEMx174 cells distinguished this new SIV from all previously reported sooty mangabey-derived viruses (SIVsm), which grow well in this cell line. SIVrcm was also successfully transmitted (cell free) to human and rhesus PBMC as well as to Molt 4 clone 8 cells. To determine the evolutionary origins of this newly identified virus, subgenomic pol (475 bp) and gag (954 bp) gene fragments were amplified from infected cell culture DNA and sequenced. The position of SIVrcm relative to those of members of the other primate lentivirus lineages was then examined in evolutionary trees constructed from deduced protein sequences. This analysis revealed significantly discordant phylogenetic positions of SIVrcm in the two genomic regions. In trees derived from partial gag sequences, SIVrcm clustered independently from all other HIV and SIV strains, consistent with a new primate lentivirus lineage. However, in trees derived from pol sequences, SIVrcm grouped with the HIV-1/SIVcpz lineage. These findings suggest that the SIVrcm genome is mosaic and possibly is the result of a recombination event involving divergent lentiviruses in the distant past. Further analysis of this and other SIVrcm isolates may shed new light on the origin of HIV-1.