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Tongo M.,University of Cape Town | Tongo M.,Institute of Medical Research and Study of Medicinal Plants IMPM | Burgers W.A.,University of Cape Town
Viruses | Year: 2014

The extraordinary variability of HIV-1 poses a major obstacle to vaccine development. The effectiveness of a vaccine is likely to vary dramatically in different populations infected with different HIV-1 subtypes, unless innovative vaccine immunogens are developed to protect against the range of HIV-1 diversity. Immunogen design for stimulating neutralizing antibody responses focuses on “breadth”-the targeting of a handful of highly conserved neutralizing determinants on the HIV-1 Envelope protein that can recognize the majority of viruses across all HIV-1 subtypes. An effective vaccine will likely require the generation of both broadly cross-neutralizing antibodies and non-neutralizing antibodies, as well as broadly cross-reactive T cells. Several approaches have been taken to design such broadly-reactive and cross-protective T cell immunogens. Artificial sequences have been designed that reduce the genetic distance between a vaccine strain and contemporary circulating viruses; “mosaic” immunogens extend this concept to contain multiple potential T cell epitope (PTE) variants; and further efforts attempt to focus T cell immunity on highly conserved regions of the HIV-1 genome. Thus far, a number of pre-clinical and early clinical studies have been performed assessing these new immunogens. In this review, the potential use of these new immunogens is explored. © 2014 by the authors; licensee MDPI, Basel, Switzerland.

Nkouawa A.,Asahikawa Medical College | Nkouawa A.,Institute of Medical Research and Study of Medicinal Plants IMPM | Sako Y.,Asahikawa Medical College | Li T.,Centers for Disease Control and Prevention | And 8 more authors.
Journal of Clinical Microbiology | Year: 2010

We compared the performance of loop-mediated isothermal amplification (LAMP) with that of a multiplex PCR method for differential detection of human Taenia parasites in fecal specimens from taeniasis patients. The LAMP method, with no false positives, showed a higher sensitivity (88.4%) than the multiplex PCR (37.2%). Thus, it is expected that the LAMP method has a high value for molecular diagnosis of taeniasis. Copyright © 2010, American Society for Microbiology. All Rights Reserved.

Tongo M.,International Center for Genetic Engineering and Biotechnology | Tongo M.,University of Cape Town | Tongo M.,Institute of Medical Research and Study of Medicinal Plants IMPM | Essomba R.G.,International Center for Genetic Engineering and Biotechnology | And 14 more authors.
Infection, Genetics and Evolution | Year: 2015

HIV-1 subtype G has played an early and central role in the emergent complexity of the HIV-1 group M (HIV-1M) epidemic in central/west Africa. Here, we analysed new subtype G env sequences sampled from 8 individuals in Yaoundé, Cameroon during 2007-2010, together with all publically available subtype G-attributed full-length env sequences with known sampling dates and locations. We inferred that the most recent common ancestor (MRCA) of the analysed subtype G env sequences most likely occurred in ~1953 (95% Highest Posterior Density interval [HPD] 1939-1963): about 15. years earlier than previous estimates. We found that the subtype G env phylogeny has a complex structure including seven distinct lineages, each likely dating back to the late 1960s or early 1970s. Sequences from Angola, Gabon and the Democratic Republic of Congo failed to group consistently in these lineages, possibly because they are related to more ancient sequences that are poorly sampled. The circulating recombinant form (CRF), CRF06_cpx env sequences but not CRF25_cpx env sequences are phylogenetically nested within the subtype G clade. This confirms that the CRF06_cpx env plausibly was derived through recombination from a subtype G parent, and suggests that the CRF25_cpx env was likely derived from an HIV-1M lineage related to the MRCA of subtype G that has remained undiscovered and may be extinct. Overall, this fills important gaps in our knowledge of the early events in the spread of HIV-1M. © 2015 Elsevier B.V.

Bigoga J.D.,University of Yaounde I | Nanfack F.M.,University of Yaounde I | Awono-Ambene P.H.,Organization de Coordination Pour la Lutte Contre les Endemies en Afrique Centrale OCEAC | Patchoke S.,Ministry of Public Health | And 6 more authors.
Parasites and Vectors | Year: 2012

Background: Development of large scale agro-industries are subject to serious environmental modifications. In malaria endemic areas this would greatly impact on the transmission paradigm. Two cross-sectional entomological surveys to characterize the Anopheles fauna and their entomological inoculation rates were conducted during May 2010 (peak rainy season) and December 2010 (peak dry season) in the intense rubber cultivated area of Niete in southern forested Cameroon. Methods: Mosquitoes were sampled by night collections on human volunteers, identified morphologically and members of the Anopheles gambiae complex further identified to species and molecular form. Parity status was determined following the dissection of the ovaries. Plasmodium falciparum circumsporozoite antigen indices were estimated after the identification of CS antigen by ELISA and the average entomological inoculation rates determined. Results: A total of 1187 Anopheles was collected, 419 (35.3%) in the rainy season and 768 (64.7%) in the dry season. Species found were the M molecular form of An. gambiae s.s (66.8%), An. ziemanni (28.3%), An. paludis (4.7%), An. smithii (0.2%). An. gambiae M-form was the principal species in the dry (56.2%) and wet (86.2%) seasons. Average overall entomological inoculation rate for the malaria vectors varied between the dry season (1.09 ib/p/n) and the rainy season (2.30 ib/p/n). Conclusions: Malaria transmission in Niete occurs both in the dry and rainy season with the intensities peaking in the dry season. This is unlike previous studies in other areas of southern forested Cameroon where transmission generally peaks in the rainy season. Environmental modifications due to agro-industrial activities might have influenced vector distribution and the dynamics of malaria transmission in this area. This necessitates the possible implementation of control strategies that are related to the eco-geography of the area. © 2012 Bigoga et al.; licensee BioMed Central Ltd.

Kwon J.C.,Sejong University | Leopold E.N.,University of Ngaoundere | Jung M.C.,Sejong University | Emmanuel E.G.,University of Yaounde I | And 4 more authors.
Geosciences Journal | Year: 2012

The objectives of this study are to evaluate the extent of heavy metal pollution in water at the Municipal Lake of Yaounde, and to find out their variability and origin. Water from fifteen selected sites of the lake and River Mingoa, Cameroon was sampled in August 16 th of 2005 and 2006 and in 30 th August 2007 during the minor dry season; and subjected to the analyses of physicochemical parameters and various elements. In addition, multivariate data analysis techniques including principal component analysis (PCA) were utilized to determine the variations in heavy metal content in the Municipal Lake water and their natural or anthropogenic sources. The chemical results indicated that concentrations of Al, Fe, Mn, Cd and Pb in the study area exceeded the drinking water quality and they would pose health risk for users of these waters. This is evidence that River Mingoa, the main tributary to the Municipal Lake is the main collector of pollutants from activities in the sloping side of the Municipal Lake. Based on the multivariate statistical analysis, very high positive correlations were observed between elements, and five factors computed from PCA explained 86. 6% of total variance. These factor loadings are mainly controlled by anthropogenic inputs, lithogenic processes during weathering progress of natural parent materials and local geology. © 2012 The Association of Korean Geoscience Societies and Springer-Verlag Berlin Heidelberg.

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