BackgroundGroup B streptococcus (GBS), which asymptomatically colonises the vaginal and rectal areas of women, is the leading cause of septicemia, meningitis and pneumonia in neonates. In Tanzania no studies have been done on GBS colonisation of pregnant women and neonates. This study was conducted in Dar es Salaam, Tanzania to determine the prevalence of GBS colonisation among pregnant women, the neonatal colonisation rate and the antimicrobial susceptibility, thus providing essential information to formulate a policy for treatment and prevention regarding perinatal GBS diseases.MethodsThis cross sectional study involved 300 pregnant women attending antenatal clinic and their newborns delivered at Muhimbili National Hospital (MNH) between October 2008 and March 2009. High vaginal, rectal, nasal, ear and umbilical swabs were cultured on Todd Hewitt Broth and in 5% sheep blood agar followed by identification of isolates using conventional methods and testing for their susceptibility to antimicrobial agents using the Kirby-Bauer method.ResultsGBS colonisation was confirmed in 23% of pregnant women and 8.9% of neonates. A higher proportion of GBS were isolated from the vagina (12.3%) as compared to the rectum (5%). Prolonged duration of labour (>12 hrs) was significantly shown to influence GBS colonisation in neonates P < 0.05. Other risk factors such as prolonged rupture of membrane, intrapartum fever, low birth weight and HIV infection did not correlate with GBS colonisation. All isolates were sensitive to vancomycin and ampicillin. Resistance to clindamycin, erythromycin and penicillin G was found to 17.6%, 13% and 9.4%, respectively.ConclusionOur findings seem to suggest that a quarter of pregnant women attending ANC clinic at MNH and approximately 10% of their newborns are colonised with GBS. All isolates were found to be sensitive to vancomycin and ampicillin which seem to be the most effective antibiotics for the time being. However there is a need for continuous antibiotics surveillance of GBS to monitor trend of resistance. The high isolation frequency of GBS among pregnant women suggests routine antenatal screening at 35 to 37 weeks of gestation in order to provide antibiotic prophylaxis to GBS carrier.

Background We conducted a phase I/II randomized placebo-controlled trial with the aim of exploring whether priming with a low intradermal dose of a multiclade, multigene HIV-1 DNA vaccine could improve the immunogenicity of the same vaccine given intramuscularly prior to boosting with a heterologous HIV-1 MVA among healthy adults in Dar es Salaam, Tanzania. Methods Sixty HIV-uninfected volunteers were randomized to receive DNA plasmid vaccine 1 mg intradermally (id), n = 20, or 3.8 mg intramuscularly (im), n = 20, or placebo, n = 20, using a needle-free injection device. DNA plasmids encoding HIV-1 genes gp160 subtype A, B, C; rev B; p17/p24 gag A, B and Rtmut B were given at weeks 0, 4 and 12. Recombinant MVA (108 pfu) expressing HIV-1 Env, Gag, Pol of CRF01_AE or placebo was administered im at month 9 and 21. Results The vaccines were well tolerated. Two weeks after the third HIV-DNA injection, 22/38 (58%) vaccinees had IFN-γ ELISpot responses to Gag. Two weeks after the first HIV-MVA boost all 35 (100%) vaccinees responded to Gag and 31 (89%) to Env. Two to four weeks after the second HIV-MVA boost, 28/29 (97%) vaccinees had IFN-γ ELISpot responses, 27 (93%) to Gag and 23 (79%) to Env. The id-primed recipients had significantly higher responses to Env than im recipients. Intracellular cytokine staining for Gag-specific IFN-γ/IL-2 production showed both CD8+ and CD4+ T cell responses. All vaccinees had HIV-specific lymphoproliferative responses. All vaccinees reacted in diagnostic HIV serological tests and 26/29 (90%) had antibodies against gp160 after the second HIV-MVA boost. Furthermore, while all of 29 vaccinee sera were negative for neutralizing antibodies against clade B, C and CRF01 AE pseudoviruses in the TZM-bl neutralization assay, in a PBMC assay, the response rate ranged from 31% to 83% positives, depending upon the clade B or CRF01_AE virus tested. This vaccine approach is safe and highly immunogenic. Low dose, id HIV-DNA priming elicited higher and broader cell-mediated immune responses to Env after HIV-MVA boost compared to a higher HIV-DNA priming dose given im. Three HIV-DNA priming immunizations followed by two HIV-MVA boosts efficiently induced Env-antibody responses.

BackgroundIntradermal priming with HIV-1 DNA plasmids followed by HIV-1MVA boosting induces strong and broad cellular and humoral immune responses. In our previous HIVIS-03 trial, we used 5 injections with 2 pools of HIV-DNA at separate sites for each priming immunization. The present study explores whether HIV-DNA priming can be simplified by reducing the number of DNA injections and administration of combined versus separated plasmid pools.MethodsIn this phase IIa, randomized trial, priming was performed using 5 injections of HIV-DNA, 1000 μg total dose, (3 Env and 2 Gag encoding plasmids) compared to two “simplified” regimens of 2 injections of HIV-DNA, 600 μg total dose, of Env- and Gag-encoding plasmid pools with each pool either administered separately or combined. HIV-DNA immunizations were given intradermally at weeks 0, 4, and 12. Boosting was performed intramuscularly with 108 pfu HIV-MVA at weeks 30 and 46.Results129 healthy Tanzanian participants were enrolled. There were no differences in adverse events between the groups. The proportion of IFN-γ ELISpot responders to Gag and/or Env peptides after the second HIV-MVA boost did not differ significantly between the groups primed with 2 injections of combined HIV-DNA pools, 2 injections with separated pools, and 5 injections with separated pools (90%, 97% and 97%). There were no significant differences in the magnitude of Gag and/or Env IFN-γ ELISpot responses, in CD4+ and CD8+ T cell responses measured as IFN-γ/IL-2 production by intracellular cytokine staining (ICS) or in response rates and median titers for binding antibodies to Env gp160 between study groups.ConclusionsA simplified intradermal vaccination regimen with 2 injections of a total of 600 μg with combined HIV-DNA plasmids primed cellular responses as efficiently as the standard regimen of 5 injections of a total of 1000 μg with separated plasmid pools after boosting twice with HIV-MVA.Trial RegistrationWorld Health Organization International Clinical Trials Registry Platform PACTR2010050002122368

Vaccine-induced HIV antibodies were evaluated in serum samples collected from healthy Tanzanian volunteers participating in a phase I/II placebo-controlled double blind trial using multi-clade, multigene HIV-DNA priming and recombinant modified vaccinia Ankara (HIV-MVA) virus boosting (HIVIS03). The HIV-DNA vaccine contained plasmids expressing HIV-1 gp160 subtypes A, B, C, Rev B, Gag A, B and RTmut B, and the recombinant HIV-MVA boost expressed CRF01_AE HIV-1 Env subtype E and Gag-Pol subtype A. While no neutralizing antibodies were detected using pseudoviruses in the TZM-bl cell assay, this prime-boost vaccination induced neutralizing antibodies in 83% of HIVIS03 vaccinees when a peripheral blood mononuclear cell (PBMC) assay using luciferase reporter-infectious molecular clones (LucR-IMC) was employed. The serum neutralizing activity was significantly (but not completely) reduced upon depletion of natural killer (NK) cells from PBMC (p=0.006), indicating a role for antibody-mediated Fcγ-receptor function. High levels of antibody-dependent cellular cytotoxicity (ADCC)-mediating antibodies against CRF01_AE and/or subtype B were subsequently demonstrated in 97% of the sera of vaccinees. The magnitude of ADCC-mediating antibodies against CM235 CRF01_AE IMC-infected cells correlated with neutralizing antibodies against CM235 in the IMC/PBMC assay. In conclusion, HIV-DNA priming, followed by two HIV-MVA boosts elicited potent ADCC responses in a high proportion of Tanzanian vaccinees. Our findings highlight the potential of HIV-DNA prime HIV-MVA boost vaccines for induction of functional antibody responses and suggest this vaccine regimen and ADCC studies as potentially important new avenues in HIV vaccine development.Trial RegistrationControlled-Trials ISRCTN90053831 The Pan African Clinical Trials Registry ATMR2009040001075080 (currently PACTR2009040001075080)