• Thematic field of study: Species diversity and insecticide Resistance in ANOPHELES in Libreville
• Supervisor(s): Prof Marielle Bouyoy Akotet, Prof Patricia Mawili Mboumba, Dr Noe Patrick Mbondoukwe, Dr Ornella Mbang Nguema, Dr Jacques Mari Ndong Ngomo.
• Contact details: dpmawili@gmail.com

Summary of Hosting Lab

The activities of the Joint Research Unit on Infectious Agents and Associated Pathologies focus on the genetic diversity of pathogens. Studies on factors influencing the expression of known or emerging parasites, bacteria and viruses as well as on vectors behavioural changes are conducted in urban areas. Vectors identification and distribution in these areas are performed.

Within JRAIP, a team is working on molecular characterization using conventional PCR, real-time PCR and RFLP-PCR.

Our unit is a research unit based at the University of Health Sciences in which students are introduced to basic, clinical and operational research; and carried out their research work.

Project Description

Currently, our team performs an inventory of potential vectors (Aedes and Anopheles) in urban areas, notably in the districts of Libreville. Therefore, the present project will be focused on the analysis of the species diversity of Anopheles. The objective is to identify using PCR
techniques Anopheles species and to detect the Kdr mutation. Collection of the larva will be performed in breeding sites close to households.

Publications

Ndong Ngomo JM et al. Drug Resistance Molecular Markers of Plasmodium falciparum and Severity of Malaria in Febrile Children in the Sentinel Site for Malaria Surveillance of Melen in Gabon: Additional Data from the Plasmodium Diversity Network African Network. Trop Med
Infect Dis. 2023 Mar 23;8(4):184.

Mbang Nguema O et al. Variations of Glossina sp. and trypanosome species frequency within different habitats in a sleeping sickness focus, Gabon. J Infect Dev Ctries. 2019 Jan 31;13(1):67-72. doi: 10.3855/jidc.9654.

Mbang Nguema OA et al. High Frequency of Trypanosoma congolense Savannah Type (Kinetoplastida: Trypanosomatidae) Among Tsetse Flies (Diptera: Glossinidae) in a Historic Trypanosoma Foci in North-Eastern Gabon: Preliminary Study [corrected]. J Med Entomol. 2016
Jul;53(4):945-948. doi: 10.1093/jme/tjw047.

Jean-Romain Mourou et al. Malaria transmission in Libreville: results of a one year survey. Malar J. 2012 Feb 9:11:40. doi: 10.1186/1475-2875-11-40.

Jean-Romain Mourou et al. Malaria transmission and insecticide resistance of Anopheles gambiae in Libreville and Port-Gentil, Gabon. Malar J. . 2010 Nov 11:9:321. doi: 10.1186/1475-2875-9-321.

Major Lab techniques

Larva sampling; Anopheles and Aedes adults microscopic identification, Nucleic acid extraction, qPCR, results analysis and interpretation (basic data analysis), scientific communication.

• Thematic field of study: Comparison of the Indirect Immunofluorescence versus RT-PCR for the diagnosis of occult loiasis in an endemic area of Gabon
• Supervisor(s): Prof Marielle Karine Bouyou Akotet, Prof Denise Patricia Mawili Mboumba, Dr Jacques Mari Ndong Ngomo, Dr Noé Patrick M’Bondoukwé
• Contact details: dpmawili@gmail.com

Summary of Hosting Lab

The Department of Parasitology-Mycology-Tropical Medicine (DPMTM) has for main mission to diagnose parasitosis and fungal infections in Gabon. This is the reference unit in Gabon. Medical consultations are organized to receive patients and specialized laboratories are available for the detection of parasites and fungi. Regarding loiasis, tests were developed to diagnose microfilaremic and occult loiasis. The laboratory has expert World Health Organization (WHO) microscopist certified.
The Joint Research Unit on Infectious Agents and Associated Pathologies (JRAIP) is affiliated to the DPMTM, focus on the genetic diversity of pathogens, and studies on factors influencing the expression of known or emerging parasites, bacteria and viruses. Indeed, the expression of
diseases linked to these pathogens are strongly associated with the susceptibility of the hosts, in particular with the quality of their immune response. Identifying the immunologic factors involved in the severity of infectious diseases leads to the development of vaccines. Within UMRAIP, a team is working on molecular characterization using conventional PCR, real-time PCR, and RFLP PCR. Another team is studying the cytokine response of the hosts. The UMRAIP is a research unit of the University of Health Sciences in which several students have been introduced to basic, clinical, and operational research; and carried out their research work.

Project Description

Loiasis is a the second cause of medical consultations in Gabon of parasitic etiology. The prevalence is 40,0% in the country. Loiasis was considered as benign but with the onchocerciasis control program with mass drug administration of Ivermectin, serious adverse events were
observed in patients with high microfilaremia (> 8000 microfilaremia (mf)/mL). Moreover in patients with microfilaremia superior to 30 000 mf/mL, without ivermectin intervention, has a reduced lifespan. These observations gave more interest to the disease and some authors want to
add loiasis in the WHO Neglected Tropical Diseases list. Two forms of loiasis are observed microfilaremic and occult.
The occult loiasis (OL) is defined as the absence of the Loa (L.) loa microfilaremia in the blood. The diagnosis is mainly based on the immunological techniques notably with the indirect immunofluorescence (IIF) when parasitological techniques failed to put in evidence the parasite. There is few data on the epidemiology of OL and few works on the development of tools to diagnose this particular form. Moreover, 60-70% of patients with loiasis has a OL. The development of molecular tools will help to diagnose submicroscopic infection.
Thus the objective is to determine the performance of the RT-PCR in comparison with the IIF for the diagnosis of OL in samples from patients living in highly endemic areas to loiasis. During this project, IIF and RT-PCR will be developed to determine the sensitivity, specificity, positive and negative predictive values of the RT-PCR versus IIF.

Publications

Bouyou Akotet MK, Owono-Medang M, Mawili-Mboumba DP, et al. The relationship between microfilaraemic and amicrofilaraemic loiasis involving co-infection with Mansonella perstans and clinical symptoms in an exposed population from Gabon. Journal of Helminthology. 2016;90(4):469-475. doi:10.1017/S0022149X15000607

M’bondoukwé NP, Kendjo E, Mawili-Mboumba DP, Lengongo JVK, Mbouoronde CO, Nkoghe D, Touré F, Bouyou-Akotet MK. Correction to: prevalence of and risk factors for malaria, filariasis, and intestinal parasites as single infections or co-infections in different settlements of Gabon, Central Africa. Infect Dis Poverty. 2018 Apr 20;7(1):38. doi:10.1186/s40249-018-0415-6. Erratum for: Infect Dis Poverty. 2018 Jan 30;7(1):6. doi:10.1186/s40249-017-0381-4. PMID: 29678200; PMCID: PMC5909251.

Ta-Tang TH, Berzosa P, Rubio JM, Romay-Barja M, Ncogo P, Agudo D, Herrador Z, Cerrada-Gálvez L, Benito A. Evaluation of LAMP for the diagnosis of Loa loa infection in dried blood spots compared to PCR-based assays and microscopy. Mem Inst Oswaldo Cruz. 2022 Feb
11;116:e210210. doi: 10.1590/0074-02760210210. PMID: 35170676; PMCID:PMC8843042.

Veletzky L, Eberhardt KA, Hergeth J, Stelzl DR, Zoleko Manego R, Kreuzmair R, Burger G,Mischlinger J, McCall MBB, Mombo-Ngoma G, Adegnika AA, Agnandji ST, Matsiegui PB,Lell B, Kremsner P, Mordmüller B, Tappe D, Ramharter M. Analysis of diagnostic test outcomes in a large loiasis cohort from an endemic region: Serological tests are often false negative in hyper-microfilaremic infections. PLoS Negl Trop Dis. 2024 Mar 14;18(3):e0012054. doi: 10.1371/journal.pntd.0012054. PMID: 38484012; PMCID:PMC10965051.

Major Lab techniques

RT-PCR, sample processing, Immunofluorescence Indirect, basic microscopy, biobank, data management, data analysis with R, scientific communication.

• Thematic field of study: Resistance and genetic diversity of Candida albicans strains in immunocompromised subjects in Libreville
• Supervisor(s): Ndong Ngomo JM, Sibi Matotou HR, M’Bondoukwé NP, Mawili-Mboumba DP, Bouyou-Akotet MK
• Contact details: 06etindong@gmail.com

Summary of Hosting Lab

Unité Mixte de Recherche sur les Agent Infectieux et leur parathologie (UMRAIP) is a research and diagnostic unit attached to the Department of Parasitology-Mycology at the Université des Sciences de la Santé (USS). The laboratory was set up to provide molecular diagnostics for any patient suspected of having coronavirus disease-2019 (COVID-19), and to assess immunoglobulin levels (VIDAS) and haematological toxicity
(XM1000) in vaccinated participants. The laboratory is equipped with a thermal cycler for genotyping by RT-PCR, multiplex PCR and qRT-PCR, and an Applied Biosystem thermal cycler for conventional PCR/ PCR-RFLP. The research themes developed at UMRAIP aim to provide information on the genomic level of pathogens in order to guarantee the efficacy of antifungal agents recommended by the WHO. In fact, Dr Ndong has taken part in several genomic studies on resistance and genetic diversity of Plasmodium falciparum strains, thanks to the Plasmodium Diversity Network African (PDNA) network and collaboration with Brown University (USA). This project is an opportunity for us to collaborate with our partner establishment in Brains to train students in molecular biology techniques, and to conduct research project.

Project Description

The immunosuppressed, elderly population and palliative patients are highly susceptible to Candida infections. Oral candidiasis results in local oral pain and discomfort, enhanced oral dryness, loss of taste and aversion to food and may lead to secondary complications. Failure to treat candidemia in sufficient time is associated with a significant risk of mortality, especially in severe cases that have evolved into invasive fungal diseases. Azole resistance frequently occurs when the target (14-α-demethylase) is altered. This enzyme is involved in ergosterol synthesis within the membrane and is encoded by the Cyp51 gene (also known as ERG11). Point mutations resulting in a defective Erg11 enzyme unable to bind to azoles have been clustered in three hotspot regions: 105–165, 266–287 and 405–488. In addition, genomic studies have justified these failures of fluconazole therapy by the existence of non-synonymous mutations detected in the mdr1 gene and increased copy numbers in the cdr1 and cdr2 genes. Nevertheless, studies evaluating the prevalence of specific resistance markers associated with fluconazole resistance in Africa are rare. The aim of this study will be to estimate the frequency of fluconazole resistance markers specific of ERG11 gene in HIV patients treated in fluconazole by RT-PCR. A cross-sectional study will be carried out at UMRAIP using samples collected from people living with HIV at the Centre Hospitalier Universitaire de Libreville. After nucleic acid extraction, RT-PCR will be used for mutations detection of ERG11.

Publications

High Cryptococcal Antigenuria Prevalence in a Population of PLHIV with Neurological Symptoms Hospitalized in the Infectious Diseases Wards of the Centre Hospitalier Universitaire de Libreville, Gabon. Sibi Matotou RH, Mawili-Mboumba DP, Manomba C, Moutombi Ditombi BC, Mihindou CJ, Moussavou Mabicka DA, Mounomby A, Nzenze Afene S, Bouyou Akotet MK.Trop Med Infect Dis. 2024 Dec 23;9(12):312. doi: 10.3390/tropicalmed9120312.

Drug Resistance Molecular Markers of Plasmodium falciparum and Severity of Malaria in Febrile Children in the Sentinel Site for Malaria Surveillance of Melen in Gabon: Additional Data from the Plasmodium Diversity Network African Network. Ndong Ngomo JM, Mawili-Mboumba DP, M’Bondoukwé NP, Ditombi BM, Koumba Lengongo JV, Batchy Ognagosso FB, Bouyou-Akotet MK.Trop Med Infect Dis. 2023 Mar 23;8(4):184. doi: 10.3390/tropicalmed8040184.

Spatial and temporal distribution of Pfmsp1 and Pfmsp2 alleles and genetic profile change of Plasmodium falciparum populations in Gabon. Ndong Ngomo JM, M’Bondoukwe NP, Yavo W, Bongho Mavoungou LC, Bouyou-Akotet MK, Mawili-Mboumba DP.Acta Trop. 2018 Feb;178:27-
33. doi: 10.1016/j.actatropica.2017.09.026. Epub 2017 Oct 7.

Major Lab techniques

Nested PCR
RT-PCR
qRT-PCR
ELISA (VIDAS)
Hematology (SYSMEX-XN1000)