NIMR Mbeya Medical Research Programme

Mbeya, Tanzania

NIMR Mbeya Medical Research Programme

Mbeya, Tanzania
SEARCH FILTERS
Time filter
Source Type

Nofemela A.,University of Cape Town | Bandawe G.,University of Cape Town | Thebus R.,University of Cape Town | Marais J.,University of Cape Town | And 7 more authors.
Virology | Year: 2011

The Mbeya region of Tanzania has a genetically complex HIV epidemic with multiple subtypes and recombinant forms circulating, together with a high frequency of dual infections with more than one subtype. This study aimed to determine whether this impacted the HIV-1 transmission bottleneck. A total of 210 env sequences from 22 participants were generated from recently infected women from Mbeya using the single genome amplification approach. Participants were infected with subtypes C (n= 9), A (n= 4), or D (n= 1), and recombinants AC (n= 4), CD (n= 2), AD (n= 1), or ACD (n= 1). Sixteen participants (73%) were infected with a single variant; five (23%) with multiple variants; and one (4%) was dually infected. Thus the frequency of single variant infections was similar to cohorts located in genetically restricted subtype B or C epidemics, suggesting that multiple circulating subtypes and unique recombinant forms do not have a significant impact on the transmission bottleneck. © 2011 Elsevier Inc.


Rose M.V.,Copenhagen University | Kimaro G.,National Institute for Medical Research | Kroidl I.,NIMR Mbeya Medical Research Programme | Kroidl I.,Ludwig Maximilians University of Munich | And 5 more authors.
European Respiratory Journal | Year: 2013

The performance of QuantiFERON microtube (QFT-MT), using 0.9 mL blood, and QuantiFERON-TB Gold in-tube test (QFT-IT) (3 mL blood), for diagnosing tuberculosis (TB) was compared in children and adults in an endemic setting. In 152 children with suspected TB and 87 adults with confirmed TB, QFT-IT was compared with two QFT-MT concentrations (QFT-MT A and B). Proportions of positive and indeterminate results, interferon (IFN)-γ responses, interassay agreement and sensitivity were assessed. We found similar proportions of indeterminate results, levels of IFN-γ and comparable sensitivity. The interassay agreement was moderate in all children (QFT-IT versus QFT-MT A: 85%, k50.44 and QFT-IT versus QFT-MT B: 88%, k=50.50) and adults (QFT-IT versus QFT-MT A: 88%, k50.50 and QFT-IT versus QFT-MT B: 89%, k=50.49). Sensitivity was low (QFT-IT 23%, QFTMT A 18% and B 19%) in children with confirmed or highly probable TB compared with adults (83%, 86% and 88%, respectively). The QFT-MT test can be reliably performed using less than one-third of the blood volume used in QFT-IT. The reduced volume may be useful for research and future diagnosis of paediatric TB. The poor sensitivity and high indeterminate rate of both IFN-c release assays in severely ill children, with immature or impaired immunity in an endemic setting, warrants further investigations. Copyright © ERS 2013.


Heinrich N.,Ludwig Maximilians University of Munich | Saathoff E.,Ludwig Maximilians University of Munich | Weller N.,Ludwig Maximilians University of Munich | Clowes P.,Ludwig Maximilians University of Munich | And 10 more authors.
PLoS Neglected Tropical Diseases | Year: 2012

Background: The Rift Valley fever virus (RVFV) is an arthropod-borne phlebovirus. RVFV mostly causes outbreaks among domestic ruminants with a major economic impact. Human infections are associated with these events, with a fatality rate of 0.5-2%. Since the virus is able to use many mosquito species of temperate climates as vectors, it has a high potential to spread to outside Africa. Methodology/Principal Findings: We conducted a stratified, cross-sectional sero-prevalence survey in 1228 participants from Mbeya region, southwestern Tanzania. Samples were selected from 17,872 persons who took part in a cohort study in 2007 and 2008. RVFV IgG status was determined by indirect immunofluorescence. Possible risk factors were analyzed using uni- and multi-variable Poisson regression models. We found a unique local maximum of RVFV IgG prevalence of 29.3% in a study site close to Lake Malawi (N = 150). The overall seroprevalence was 5.2%. Seropositivity was significantly associated with higher age, lower socio-economic status, ownership of cattle and decreased with distance to Lake Malawi. A high vegetation density, higher minimum and lower maximum temperatures were found to be associated with RVFV IgG positivity. Altitude of residence, especially on a small scale in the high-prevalence area was strongly correlated (PR 0.87 per meter, 95% CI = 0.80-0.94). Abundant surface water collections are present in the lower areas of the high-prevalence site. RVF has not been diagnosed clinically, nor an outbreak detected in the high-prevalence area. Conclusions: RVFV is probably circulating endemically in the region. The presence of cattle, dense vegetation and temperate conditions favour mosquito propagation and virus replication in the vector and seem to play major roles in virus transmission and circulation. The environmental risk-factors that we identified could serve to more exactly determine areas at risk for RVFV endemicity. © 2012 Heinrich et al.


Rose M.V.,Copenhagen University | Rose M.V.,University Hospital Hvidovre | Kimaro G.,National Institute for Medical Research | Nissen T.N.,University Hospital Hvidovre | And 6 more authors.
PLoS ONE | Year: 2012

Aim: To determine whether QuantiFERON®-TB Gold In-Tube (QFT) can contribute to the diagnosis of active tuberculosis (TB) in children in a high-burden setting and to assess the performance of QFT and tuberculin skin test (TST) in a prospective cohort of TB suspect children compared to adults with confirmed TB in Tanzania. Methods: Sensitivity and specificity of QFT and TST for diagnosing active TB as well as indeterminate QFT rates and IFN-γ levels were assessed in 211 TB suspect children in a Tanzanian district hospital and contrasted in 90 adults with confirmed pulmonary TB. Results: Sensitivity of QFT and TST in children with confirmed TB was 19% (5/27) and 6% (2/31) respectively. In adults sensitivity of QFT and TST was 84% (73/87) and 85% (63/74). The QFT indeterminate rate in children and adults was 27% and 3%. Median levels of IFN-γ were lower in children than adults, particularly children <2 years and HIV infected. An indeterminate result was associated with age <2 years but not malnutrition or HIV status. Overall childhood mortality was 19% and associated with an indeterminate QFT result at baseline. Conclusion: QFT and TST showed poor performance and a surprisingly low sensitivity in children. In contrast the performance in Tanzanian adults was good and comparable to performance in high-income countries. Indeterminate results in children were associated with young age and increased mortality. Neither test can be recommended for diagnosing active TB in children with immature or impaired immunity in a high-burden setting. © 2012 Rose et al.


PubMed | Ludwig Maximilians University of Munich, Charles University, NIMR Mbeya Medical Research Programme, University of Alabama at Birmingham and Palacky University
Type: | Journal: AIDS research and therapy | Year: 2014

HIV-1 entry into host cells is mediated by interactions between the virus envelope glycoprotein (gp120/gp41) and host-cell receptors. N-glycans represent approximately 50% of the molecular mass of gp120 and serve as potential antigenic determinants and/or as a shield against immune recognition. We previously reported that N-glycosylation of recombinant gp120 varied, depending on the producer cells, and the glycosylation variability affected gp120 recognition by serum antibodies from persons infected with HIV-1 subtype B. However, the impact of gp120 differential glycosylation on recognition by broadly neutralizing monoclonal antibodies or by polyclonal antibodies of individuals infected with other HIV-1 subtypes is unknown.Recombinant multimerizing gp120 antigens were expressed in different cells, HEK 293T, T-cell, rhabdomyosarcoma, hepatocellular carcinoma, and Chinese hamster ovary cell lines. Binding of broadly neutralizing monoclonal antibodies and polyclonal antibodies from sera of subtype A/C HIV-1-infected subjects with individual gp120 glycoforms was assessed by ELISA. In addition, immunodetection was performed using Western and dot blot assays. Recombinant gp120 glycoforms were tested for inhibition of infection of reporter cells by SF162 and YU.2 Env-pseudotyped R5 viruses.We demonstrated, using ELISA, that gp120 glycans sterically adjacent to the V3 loop only moderately contribute to differential recognition of a short apex motif GPGRA and GPGR by monoclonal antibodies F425 B4e8 and 447-52D, respectively. The binding of antibodies recognizing longer peptide motifs overlapping with GPGR epitope (268 D4, 257 D4, 19b) was significantly altered. Recognition of gp120 glycoforms by monoclonal antibodies specific for other than V3-loop epitopes was significantly affected by cell types used for gp120 expression. These epitopes included CD4-binding site (VRC03, VRC01, b12), discontinuous epitope involving V1/V2 loop with the associated glycans (PG9, PG16), and an epitope including V3-base-, N332 oligomannose-, and surrounding glycans-containing epitope (PGT 121). Moreover, the different gp120 glycoforms variably inhibited HIV-1 infection of reporter cells.Our data support the hypothesis that the glycosylation machinery of different cells shapes gp120 glycosylation and, consequently, impacts envelope recognition by specific antibodies as well as the interaction of HIV-1 gp120 with cellular receptors. These findings underscore the importance of selection of appropriately glycosylated HIV-1 envelope as a vaccine antigen.


Raska M.,Palacky University | Raska M.,University of Alabama at Birmingham | Czernekova L.,Palacky University | Moldoveanu Z.,University of Alabama at Birmingham | And 11 more authors.
AIDS Research and Therapy | Year: 2014

Background: HIV-1 entry into host cells is mediated by interactions between the virus envelope glycoprotein (gp120/gp41) and host-cell receptors. N-glycans represent approximately 50% of the molecular mass of gp120 and serve as potential antigenic determinants and/or as a shield against immune recognition. We previously reported that N-glycosylation of recombinant gp120 varied, depending on the producer cells, and the glycosylation variability affected gp120 recognition by serum antibodies from persons infected with HIV-1 subtype B. However, the impact of gp120 differential glycosylation on recognition by broadly neutralizing monoclonal antibodies or by polyclonal antibodies of individuals infected with other HIV-1 subtypes is unknown.Methods: Recombinant multimerizing gp120 antigens were expressed in different cells, HEK 293T, T-cell, rhabdomyosarcoma, hepatocellular carcinoma, and Chinese hamster ovary cell lines. Binding of broadly neutralizing monoclonal antibodies and polyclonal antibodies from sera of subtype A/C HIV-1-infected subjects with individual gp120 glycoforms was assessed by ELISA. In addition, immunodetection was performed using Western and dot blot assays. Recombinant gp120 glycoforms were tested for inhibition of infection of reporter cells by SF162 and YU.2 Env-pseudotyped R5 viruses.Results: We demonstrated, using ELISA, that gp120 glycans sterically adjacent to the V3 loop only moderately contribute to differential recognition of a short apex motif GPGRA and GPGR by monoclonal antibodies F425 B4e8 and 447-52D, respectively. The binding of antibodies recognizing longer peptide motifs overlapping with GPGR epitope (268 D4, 257 D4, 19b) was significantly altered. Recognition of gp120 glycoforms by monoclonal antibodies specific for other than V3-loop epitopes was significantly affected by cell types used for gp120 expression. These epitopes included CD4-binding site (VRC03, VRC01, b12), discontinuous epitope involving V1/V2 loop with the associated glycans (PG9, PG16), and an epitope including V3-base-, N332 oligomannose-, and surrounding glycans-containing epitope (PGT 121). Moreover, the different gp120 glycoforms variably inhibited HIV-1 infection of reporter cells.Conclusion: Our data support the hypothesis that the glycosylation machinery of different cells shapes gp120 glycosylation and, consequently, impacts envelope recognition by specific antibodies as well as the interaction of HIV-1 gp120 with cellular receptors. These findings underscore the importance of selection of appropriately glycosylated HIV-1 envelope as a vaccine antigen. © 2014 Raska et al.; licensee BioMed Central Ltd.


Koehler R.N.,U.S. Army | Koehler R.N.,Henry M. Jackson Foundation for the Advancement of Military Medicine, Inc | Alter G.,Massachusetts General Hospital | Tovanabutra S.,U.S. Army | And 18 more authors.
Journal of Infectious Diseases | Year: 2013

Here we explore the association between killer cell immunoglobulin-like receptor (KIR)/HLA and human immunodeficiency virus type 1 (HIV-1) acquisition with different viral subtypes circulating in East Africa. In the prospective Cohort Development (CODE) cohort (Mbeya, Tanzania), carriers of KIR3DS1 and its putative ligand (HLA-A or HLA-B Bw4-80Ile alleles) showed increased HIV-1 acquisition risk (odds ratio [OR] = 3.46; 95% confidence interval [CI], 1.12-10.63; P =. 04) and a trend for enrichment for subtype A and A-containing recombinants (78% vs 46%; OR = 4.05; 95% CI,. 91-28.30; P =. 09) at the expense of subtype C (11% vs 43%; OR = 0.17; 95% CI,. 01-.97; P =. 08). In vitro, only natural killer cells from KIR3DS1(+)/HLA-Bw4-80Ile(+) healthy donors showed a 2-fold increased capacity to inhibit replication of subtype C vs subtype A viruses (P =. 01). These findings suggest the presence of an innate sieve effect and may inform HIV-1 vaccine development. © 2013 The Author 2013.


Kroidl I.,Ludwig Maximilians University of Munich | Clowes P.,NIMR Mbeya Medical Research Programme | Mwalongo W.,NIMR Mbeya Medical Research Programme | Maganga L.,NIMR Mbeya Medical Research Programme | And 11 more authors.
PLoS ONE | Year: 2012

Objective: To evaluate the diagnostic performance of two rapid detection tests (RDTs) for HIV 1/2 in plasma and in whole blood samples. Methods: More than 15,000 study subjects above the age of two years participated in two rounds of a cohort study to determine the prevalence of HIV. HIV testing was performed using the Determine HIV 1/2 test (Abbott) in the first (2006/2007) and the HIV 1/2 STAT-PAK Dipstick Assay (Chembio) in the second round (2007/2008) of the survey. Positive results were classified into faint and strong bands depending on the visual appearance of the test strip and confirmed by ELISA and Western blot. Results: The sensitivity and specificity of the Determine RDT were 100% (95% confidence interval = 86.8 to 100%) and 96.8% (95.9 to 97.6%) in whole blood and 100% (99.7 to 100%) and 97.9% (97.6 to 98.1%) in plasma respectively. Specificity was highly dependent on the tested sample type: when using whole blood, 67.1% of positive results were false positive, as opposed to 17.4% in plasma. Test strips with only faint positive bands were more often false positive than strips showing strong bands and were more common in whole blood than in plasma. Evaluation of the STAT-PAK RDT in plasma during the second year resulted in a sensitivity of 99.7% (99.1 to 99.9%) and a specificity of 99.3% (99.1 to 99.4%) with 6.9% of the positive results being false. Conclusions: Our study shows that the Determine HIV 1/2 strip test with its high sensitivity is an excellent tool to screen for HIV infection, but that - at least in our setting - it can not be recommended as a confirmatory test in VCT campaigns where whole blood is used. © 2012 Kroidl et al.


Kolk A.,Kit Koninklijk Instituut Voor Of Tropen Royal Tropical Institute | Kolk A.,University of Amsterdam | Hoelscher M.,Ludwig Maximilians University of Munich | Maboko L.,NIMR Mbeya Medical Research Programme | And 9 more authors.
Journal of Clinical Microbiology | Year: 2010

We investigated the potential of two different electronic noses (EN; code named "Rob" and "Walter") to differentiate between sputum headspace samples from tuberculosis (TB) patients and non-TB patients. Only samples from Ziehl-Neelsen stain (ZN)- and Mycobacterium tuberculosis culture-positive (TBPOS) sputum samples and ZN- and culture-negative (TBNEG) samples were used for headspace analysis; with EN Rob, we used 284 samples from TB suspects (56 TBPOS and 228 TBNEG samples), and with EN Walter, we used 323 samples from TB suspects (80 TBPOS and 243 TBNEG samples). The best results were obtained using advanced data extraction and linear discriminant function analysis, resulting in a sensitivity of 68%, a specificity of 69%, and an accuracy of 69% for EN Rob; for EN Walter, the results were 75%, 67%, and 69%, respectively. Further research is still required to improve the sensitivity and specificity by choosing more selective sensors and type of sampling technique. Copyright © 2010, American Society for Microbiology. All Rights Reserved.

Loading NIMR Mbeya Medical Research Programme collaborators
Loading NIMR Mbeya Medical Research Programme collaborators