Isolation and partial characterization of an HIV-related virus occurring naturally in chimpanzees in Gabon.

Two cases of wild-born chimpanzees which were positive for HIV-1 antibodies were observed in Gabon. These animals were never experimentally exposed to HIV-1 and had no history of inoculation with human blood products. A retrovirus was isolated from one of these chimpanzees. Several of the viral proteins from this virus, designated SIVcpz-GAB-1 (simian immunodeficiency virus from chimpanzee), differed in molecular weight from the known corresponding HIV/SIV proteins. The major gag protein of SIVcpz migrated on SDS-PAGE with a relative molecular mass of 25.5 and the outer membrane proteins were 110, 155 and 185 kD, respectively. SIVcpz did not induce severe cytopathic effects in human and chimpanzee lymphocytes. Antigenically, SIVcpz seems to be closer to HIV-1 than to HIV-2 and the other SIVs. Nucleic acid hybridization experiments appear to indicate that the virus is different from HIV-1 and HIV-2.

Seroepidemiological survey of HTLV-I infection among randomized populations of western central African countries.

Between 1987 and 1988, a survey to determine the distribution of HTLV-I infection was conducted in a representative population of adults, living in southern Chad, Cameroon, and Equatorial Guinea. Populations studied were selected by the cluster sampling technique. Sera were tested for IgG antibodies to HTLV-I by ELISA. ELISA-positive sera were retested by Western blot. The study comprised 2,301 adults, all apparently healthy. Crude prevalence rates range from 0.5 to 11.8%. We found three clearly different areas of HTLV-I seroprevalence rates. An area of low seropositivity in southern Chad and northern Cameroon (0.5-2.0%), an area of moderate seropositivity in the savannah region of Ngaoundere, Cameroon (4.2%) and in Bata, Equatorial Guinea (6.5%), and lastly an area of high seropositivity (8.6-11.8%) in the equatorial forest area of Equatorial Guinea and southern Cameroon. HTLV-I seroprevalence rates increased with age up to 12.6% after 40 years old in the areas of high seropositivity. There was no difference between male and female age-adjusted prevalence rates in all of the areas studied.

[Gonococcal infections in Gabon (Haut-Ogooué)]. / Les infections gonococciques au Gabon (Haut-Ogooué).

The isolation of N. gonorrhoeae in the region of Franceville was attempted on the one hand with 261 men and 261 women presenting urethral or cervical discharge, and on the other hand with 530 women attending a prenatal clinic of whom 42 had cervical discharge while 488 did not. Amongst the men, 69.7% of the urethritis cases were due to N. gonorrhoeae while this bacteria could be isolated from 15.3% of the women with cervical exudates. N. gonorrhoeae could be also identified in 5.5% of the pregnant women of whom 79% were without exudate. The frequency of N. gonorrhoeae isolates from STD consultations was 440 cases per year per 100,000 while the male: female ratio was 4.6. The isolation rate from pregnant women would indicate however a frequency in women in excess of 1 500 cases per 100,000. The isolation of N. gonorrhoeae was tabulated according to the age of the patients. The 15-20 year group was clearly the most frequently infected. Trichomonas was observed in 2% of the men and 23% of the women with discharges. Yeasts (chiefly Candida albicans) were found in 23.5% of the women but in none of the men.

Antibiotic susceptibility in relation to serogroup and auxotype of Neisseria gonorrhoeae isolates from Gabon.

We tested 75 beta-lactamase-positive (penicillinase-producing Neisseria gonorrhoeae; PPNG) and 147 beta-lactamase negative (non-PPNG) strains of N. gonorrhoeae obtained during a two-year period in Franceville, a semirural community in southeastern Gabon, for susceptibility to antimicrobial agents, auxotype, and serotype. The most common auxotypes were the nonrequiring and proline-requiring strains. Of the non-PPNG strains tested, 37% belonged to serogroup WI, 48% to serogroup WII, and 15% could not be grouped with commercially available antisera. Except for four strains that belonged to serogroup WII, the PPNG strains were classified as serogroup WI or ungroupable. We determined the concentrations at which 90% of strains were inhibited (MIC90) for spectinomycin (32 mg/liter for both PPNG and non-PPNG), kanamycin (32 mg/liter for both PPNG and non-PPNG), tetracycline (2 mg/liter for non-PPNG, 1 mg/liter for PPNG), cefotaxime (0.03 mg/liter for non-PPNG, 0.008 mg/liter for PPNG), and penicillin (1 mg/liter for non-PPNG, greater than 32 mg/liter for PPNG). A MIC of greater than or equal to 2 mg of tetracycline/liter was noted for 17% of the strains. Strains belonging to serogroup WII were more resistant to tetracycline and cefotaxime than other strains. Proline-requiring strains were less susceptible to tetracycline, cefotaxime, and spectinomycin than the nonrequiring strains. The decreased sensitivity to penicillin (non-PPNG strains) and tetracycline was determined by proline-requiring strains belonging to serogroup WII.

Changing antibiotic susceptibility of Neisseria gonorrhoeae in Franceville, Gabon.

Susceptibilities to penicillin, cefotaxime, kanamycin, tetracycline, and spectinomycin were measured for 5 reference strains and 302 Neisseria gonorrhoeae isolates collected between 1980 and 1985. After an initial rise, the number of penicillinase-producing strains decreased. A gradual decrease in susceptibility to spectinomycin and the appearance of tetracycline-resistant strains were also documented.

Plasmodium falciparum: sickle-cell trait is associated with higher prevalence of multiple infections in Gabonese children with asymptomatic infections.

Through PCR amplifications of the gene encoding the merozoite surface antigen 2, utilizing allele-specific 3D7 and FC27 probes, we have examined the prevalence of Plasmodium falciparum in children aged from 7 to 14 years living in a village located in the equatorial forest region of Central Africa (Gabon). Using this technique, 61% (100/163) of the blood samples were shown to be infected with P. falciparum with 24 alleles distinguished by size polymorphism and sequence type. The two main families (3D7 and FC27) and hybrid alleles were detected regardless of sex and hemoglobin phenotype. No age-related changes in prevalence of P. falciparum strains were observed; however, the prevalence of infection (42%) was significantly lower in individuals with the sickle-cell trait compared with their normal-hemoglobin counterparts (68%). Mixtures of genetically distinct parasite clones were present in 82% of children carrying the sickle-cell trait but in only 58% of normal-hemoglobin carriers. The significance of these observations regarding the design and interpretation of epidemiological investigations is discussed in the context of malaria transmission in the region studied.

Mannose-binding lectin alleles in sub-Saharan Africans and relation with susceptibility to infections.

Mannose-binding lectin (MBL) plays an important role in the early stages of primary infections and during the decay of maternal antibodies in infants. Various studies have looked at the relation between serum MBL concentrations, MBL gene alterations and susceptibility to infections. We investigated the distribution of variant MBL alleles in 626 unrelated adults from sub-Saharan African countries and looked for a potential relation between these alleles and the incidence, prevalence and death rate of tuberculosis for sub-Saharan Africa. We also evaluated the relation between MBL genotypes and susceptibility to HIV-1 infection in 188 Gabonese adults. We found that (i) the prevalence of the common variant MBL alleles is correlated with the incidence of tuberculosis in sub-Saharan Africa (r=0.565), (ii) the mutant MBL G57E allele, in either the homozygous or compound heterozygous state, is associated with susceptibility to HIV-1 infection in the Gabonese population (P=0.019).Our data plus those in the literature suggest that individuals who are homozygous for the mutant MBL alleles display increased susceptibility to infections. Interestingly, we found that individuals who are heterozygous for MBL mutations are much less susceptible to infections than those who are homozygous for the wild-type MBL allele.

Prevalence of HTLV-I and HTLV-II infection in Gabon, Africa: comparison of the serological and PCR results.

A cluster sampling survey was performed in 1989 in Libreville, Gabon, to determine HTLV-I and HTLV-II prevalence and to compare the efficacy of polymerase chain reaction (PCR) and serology in detecting HTLV-I and HTLV-II infections. A total of 322 sera from adults were tested by ELISA and by Western blot (WB). The WB patterns were interpreted according to WHO criteria and those of the manufacturer. PCR analysis using primer pairs in the gag and pol region, with a specific probe for HTLV-I and HTLV-II, was performed on the lymphocytes of the 322 adults. In addition, 134/322 samples were re-tested with tax primers, in a second laboratory. Using WHO criteria, 8/322 (2.5%) samples were positive on WB and 25 were indeterminate; with the criteria of the kit, 26/322 (8.1%) were positive and 7 were indeterminate by WB. By PCR, 13 (4%) samples were positive, including 12 for HTLV-I (3.7%) and one for HTLV-II (0.3%). All 8 seropositive samples (by the WHO criteria) were positive by PCR, as were 4 out of 25 indeterminate samples. Only one out of 289 seronegative samples was positive by PCR. In contrast, only 12/26 positive samples by the kit criteria were confirmed by PCR. These results confirm the relatively high HTLV-I/II seroprevalence observed in Gabon. HTLV-I infection is preponderant, but HTLV-II is also present. The WHO criteria for WB give a better fit with PCR results than the kit criteria for WB. In the absence of a specific confirmatory test and based on the uncommon "seronegative" HTLV-I/II infection, the indication for PCR appears limited to the positive WB samples (to differentiate HTLV-I and II infection) and to the indeterminate WB samples.