Contribution of Anopheles gambiae sensu lato mosquitoes to malaria transmission during the dry season in Djoumouna and Ntoula villages in the Republic of the Congo.

BACKGROUND: Mosquitoes belonging to the Anopheles gambiae sensu lato complex play a major role in malaria transmission across Africa. This study assessed the relative importance of members of An. gambiae s.l. in malaria transmission in two rural villages in the Republic of the Congo. METHODS: Adult mosquitoes were collected using electric aspirators from June to September 2022 in Djoumouna and Ntoula villages and were sorted by taxa based on their morphological features. Anopheles gambiae s.l. females were also molecularly identified. A TaqMan-based assay and a nested polymerase chain reaction (PCR) were performed to determine Plasmodium spp. in the mosquitoes. Entomological indexes were estimated, including man-biting rate, entomological inoculation rate (EIR), and diversity index. RESULTS: Among 176 mosquitoes collected, An. gambiae s.l. was predominant (85.8%), followed by Culex spp. (13.6%) and Aedes spp. (0.6%). Three members of the An. gambiae s.l. complex were collected in both villages, namely An. gambiae sensu stricto (74.3%), Anopheles coluzzii (22.9%) and Anopheles arabiensis (2.8%). Three Plasmodium species were detected in An. gambiae s.s. and An. coluzzii (Plasmodium falciparum, P. malariae and P. ovale), while only P. falciparum and P. malariae were found in An. arabiensis. In general, the Plasmodium infection rate was 35.1% (53/151) using the TaqMan-based assay, and nested PCR confirmed 77.4% (41/53) of those infections. The nightly EIR of An. gambiae s.l. was 0.125 infectious bites per person per night (ib/p/n) in Djoumouna and 0.08 ib/p/n in Ntoula. The EIR of An. gambiae s.s. in Djoumouna (0.11 ib/p/n) and Ntoula (0.04 ib/p/n) was higher than that of An. coluzzii (0.01 and 0.03 ib/p/n) and An. arabiensis (0.005 and 0.0 ib/p/n). CONCLUSIONS: This study provides baseline information on the dominant vectors and dynamics of malaria transmission in the rural areas of the Republic of the Congo during the dry season. In the two sampled villages, An. gambiae s.s. appears to play a predominant role in Plasmodium spp.

Entomological indicators of Plasmodium species transmission in Goma Tsé-Tsé and Madibou districts, in the Republic of Congo.

BACKGROUND: Malaria remains a major public health problem in the Republic of Congo, with Plasmodium falciparum being the deadliest species of Plasmodium in humans. Vector transmission of malaria is poorly studied in the country and no previous report compared rural and urban data. This study aimed to determine the Anopheles fauna and the entomological indices of malaria transmission in the rural and urban areas in the south of Brazzaville, and beyond. METHODS: Indoor household mosquitoes capture using electric aspirator was performed in rural and urban areas during raining and dry seasons in 2021. The identification of Anopheles species was done using binocular magnifier and nested-PCR. TaqMan and nested-PCR were used to detect the Plasmodium species in the head/thorax and abdomens of Anopheles. Some entomological indices including the sporozoite infection rate, the entomological inoculation rate and the man biting rate were estimated. RESULTS: A total of 699 Anopheles mosquitoes were collected: Anopheles gambiae sensu lato (s.l.) (90.7%), Anopheles funestus s.l. (6.9%), and Anopheles moucheti (2.4%). Three species of An. gambiae s.l. were identified including Anopheles gambiae sensu stricto (78.9%), Anopheles coluzzii (15.4%) and Anopheles arabiensis (5.7%). The overall sporozoite infection rate was 22.3% with a predominance of Plasmodium falciparum, followed by Plasmodium malariae and Plasmodium ovale. Anopheles aggressiveness rate was higher in households from rural area (1.1 bites/night) compared to that from urban area (0.8 ib/p/n). The overall entomological inoculation rate was 0.13 ib/p/n. This index was 0.17 ib/p/n and 0.092 ib/p/n in rural and in urban area, respectively, and was similar during the dry (0.18 ib/p/n) and rainy (0.14 ib/p/n) seasons. CONCLUSION: These findings highlight that malaria transmission remains high in rural and urban area in the south of Republic of Congo despite the ongoing control efforts, thereby indicating the need for more robust interventions.

Mucosal response of inactivated and recombinant COVID-19 vaccines in Congolese individuals.

BACKGROUND: The efficacy of immunization against an airborne pathogen depends in part on its ability to induce antibodies at the major entry site of the virus, the mucosa. Recent studies have revealed that mucosal immunity is poorly activated after vaccination with messenger RNA vaccines, thus failing in blocking virus acquisition upon its site of initial exposure. Little information is available about the induction of mucosal immunity by inactivated and recombinant coronavirus disease 2019 (COVID-19) vaccines. This study aims to investigate this topic. METHODS: Saliva and plasma samples from 440 healthy Congolese were collected including (1) fully vaccinated 2 month postvaccination with either an inactivated or a recombinant COVID-19 vaccine and (2) nonvaccinated control group. Total anti-severe acute respiratory syndrome coronavirus 2 receptor-binding domain IgG and IgA antibodies were assessed using in-house enzyme-linked immunosorbent assays for both specimens. FINDINGS: Altogether, the positivity of IgG was significantly higher in plasma than in saliva samples both in vaccinated and nonvaccinated control groups. Inversely, IgA positivity was slightly higher in saliva than in plasma of vaccinated group. The overall IgG and IgA levels were respectively over 103 and 14 times lower in saliva than in plasma samples. We found a strong positive correlation between IgG in saliva and plasma also between IgA in both specimens (r = .70 for IgG and r = .52 for IgA). Interestingly, contrary to IgG, the level of salivary IgA was not different between seropositive control group and seropositive vaccinated group. No significant difference was observed between recombinant and inactivated COVID-19 vaccines in total IgG and IgA antibody concentration release 2 months postvaccination both in plasma and saliva. CONCLUSION: Inactivated and recombinant COVID-19 vaccines in use in the Republic of Congo poorly activated mucosal IgA-mediated antibody response 2 months postvaccination.

Seroprevalence of SARS-CoV-2 antibodies and associated risk factors during the second wave of infection in a university community in Cameroon.

Background: The COVID-19 pandemic has caused a public health emergency in all sectors of society, including universities and other academic institutions in Cameroon. However, little is known concerning the real prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections among student communities during the second wave of infection in Cameroon. This study aimed to estimate SARS-CoV-2 antibodies seroprevalence among participants in a university community in Cameroon. Methodology: A cross-sectional study was conducted from March to April 2021 in 547 students aged ≥18 years during a mass diagnostic campaign at the School of Health Sciences of the Catholic University of Central Africa (ESS/UCAC). The anti-SARS-CoV-2 antibody screening was done using the Panbio™ COVID-19 IgG/IgM Rapid Diagnostic Test. Results: The overall seroprevalence of SARS-CoV-2 antibodies was 27%, of which 89.9% (n = 133) was IgG, 6.7% (n = 10) IgM and 3.4% (n = 5) IgG/IgM positive. The undergraduate students represented 79% (432/547) of the total population and were highly positive with anti-SARS-CoV-2 antibodies 30% (130/432) as compared with postgraduate students 20% (23/115). The total antibody seropositivity was higher in males (34.4%) than females (24.9%). Several factors were associated with an increased risk of SARS-CoV-2 seroprevalence including the male gender (OR: 1.61 [95% confidence interval, CI 1.0-2.4]), specialization to medical laboratory (OR: 2.8 [95% CI 1.1-7.1]) and nursing sciences (OR: 2.6 [95% CI 1.1-6.2]). Conclusion: Our findings point to extensive and underreported circulation of SARS-CoV-2 in a university community during the second wave of infection in Cameroon, which likely resulted in artificially low case counts.

Plasmodium falciparum msp-1 and msp-2 genetic diversity and multiplicity of infection in isolates from Congolese patients in the Republic of Congo.

With limited up to date data from the Republic of Congo, the aim of this study was to investigate allelic polymorphism of merozoite surface protein-1 (msp-1) and merozoite surface protein-2 (msp-2). This will help assess the genetic diversity and multiplicity of Plasmodium falciparum infection (MOI), from uncomplicated malaria individuals living in Brazzaville. Between March and October 2021, a cross-sectional study was carried out at a health center in Madibou District located in the south of Brazzaville. Plasmodium infection was diagnosed in human blood by microscopy and the block 2 of P. falciparum msp-1 and block 3 of msp-2 genes were genotyped by nested PCR. Overall, 57 genotypes with fragment sizes ranging from 110 to 410 bp were recorded for msp-1, among which 25, 21, and 11 genotypes identified for K1, MAD20, and RO33 allelic families respectively. RO33 (34.3%) and MAD20 (34.3%) allelic families were more frequent compared to K1 (31.4%) although the difference was not statistically significant. Also, 47 msp-2 genotypes were identified, including 26 FC27 genotypes type, and 21 genotypes belonging to the 3D7 allelic family. FC27 was more frequent (52.3%) compared to 3D7 (47.7%). The prevalence of the polyclonal infection was 90.0% while the MOI was 2.90 ± 1.0. The MOI and polyclonal infection were not significantly associated with the parasitaemia and anaemia. This study reveals a high genetic diversity and the trend of increasing MOI of P. falciparum isolates from the south of Brazzaville, compared to the reports from the same setting before the COVID-19 pandemic.

Comparative study of Plasmodium falciparum msp-1 and msp-2 Genetic Diversity in Isolates from Rural and Urban Areas in the South of Brazzaville, Republic of Congo.

Polymorphisms in the genes encoding the merozoite surface proteins msp-1 and msp-2 are widely used markers for characterizing the genetic diversity of Plasmodium falciparum. This study aimed to compare the genetic diversity of circulating parasite strains in rural and urban settings in the Republic of Congo after the introduction of artemisinin-based combination therapy (ACT) in 2006. A cross-sectional survey was conducted from March to September 2021 in rural and urban areas close to Brazzaville, during which Plasmodium infection was detected using microscopy (and nested-PCR for submicroscopic infection). The genes coding for merozoite proteins-1 and -2 were genotyped by allele-specific nested PCR. Totals of 397 (72.4%) and 151 (27.6%) P. falciparum isolates were collected in rural and urban areas, respectively. The K1/msp-1 and FC27/msp-2 allelic families were predominant both in rural (39% and 64%, respectively) and urban (45.4% and 54.5% respectively) areas. The multiplicity of infection (MOI) was higher (p = 0.0006) in rural areas (2.9) compared to urban settings (2.4). The rainy season and the positive microscopic infection were associated with an increase in MOI. These findings reveal a higher P. falciparum genetic diversity and MOI in the rural setting of the Republic of Congo, which is influenced by the season and the participant clinical status.

Low Prevalence of Plasmodium falciparum Histidine-Rich Protein 2 and 3 Gene Deletions-A Multiregional Study in Central and West Africa.

Plasmodium falciparum parasites carrying deletions of histidine-rich protein 2 and 3 genes, pfhrp2 and pfhrp3, respectively, are likely to escape detection via HRP2-based rapid diagnostic tests (RDTs) and, consequently, treatment, posing a major risk to both the health of the infected individual and malaria control efforts. This study assessed the frequency of pfhrp2- and pfhrp3-deleted strains at four different study sites in Central Africa (number of samples analyzed: Gabon N = 534 and the Republic of Congo N = 917) and West Africa (number of samples analyzed: Nigeria N = 466 and Benin N = 120) using a highly sensitive multiplex qPCR. We found low prevalences for pfhrp2 (1%, 0%, 0.03% and 0) and pfhrp3 single deletions (0%, 0%, 0.03% and 0%) at all study sites (Gabon, the Republic of Congo, Nigeria and Benin, respectively). Double-deleted P. falciparum were only found in Nigeria in 1.6% of all internally controlled samples. The results of this pilot investigation do not point towards a high risk for false-negative RDT results due to pfhrp2/pfhrp3 deletions in Central and West African regions. However, as this scenario can change rapidly, continuous monitoring is essential to ensure that RDTs remain a suitable tool for the malaria diagnostic strategy.

Risk factors and prevalence of human African trypanosomiasis in individuals living in remote areas of the republic of Congo.

BACKGROUND: Human African trypanosomiasis (HAT) is one of the world's classical neglected tropical diseases representing a major public health threat in sub-Saharan Africa. Although the parasitic disease is in decline in the Republic of Congo, the better understanding of the epidemiological situation of active foci is required to reduce the risk of disease resurgence which could impede progress registered so far. The aim of this study was to determine the prevalence of HAT and the associated risk factors in individuals living in remote areas of the Republic of Congo. METHODS: A cross-sectional survey was carried out in volunteers living in rural settings from June 2020 to January 2021. Socio-demographic and Clinical parameters of the participants were recorded. The presence of HAT-specific antibodies was assessed in whole blood, and then confirmed in serial diluted plasma samples using Card-Agglutination Trypanosomiasis Test (CATT)/T.b. gambiense CATT. The Capillary Tube Centrifugation (CTC) and Lymph nodes (LN) examination were done for detecting trypanosome parasites in CATT-serum positive cases. The staging of positive participants was determined by cerebrospinal fluid (CSF) examination. RESULTS: Out of 8556 enrolled participants, 48.5% were more than 15 years old, 57.7% were unschooled and 67.2% practiced peasant activities. The prevalence of HAT infection was 0.3% with the predominance of patients at stage 1 of the disease (84.0%). The districts of Mindouli (OR: 25.9 (5.2-468); p = 0.0016) and Mpouya (OR: 13.3 (2.5-246); p = 0.0140) was revealed as the foci of high risk of HAT infection. Several factors were associated with an increased risk of HAT infection mainly including the non-schooling (OR: 5.1 (1.2-21.9); p = 0.0268), the life in couple or married (OR: 3.3 (1.0-11.3); p = 0.0545) and the practice of peasant activities (OR: 6.9 (2.4-29.3); p = 0.0017). CONCLUSION: This study highlights the need of revising and strengthening the strategies of HAT control in Republic of Congo, using an approach which will take into account the education level, the marital status and the occupation of the population at risk.

Human African trypanosomiasis (HAT) in the Republic of Congo: why the Congolese population is reluctant to screening?

Introduction: human African trypanosomiasis (HAT) is a neglected tropical infection, and surveillance of the disease relies on community participation in screening. This study aimed to identify the main factors associated with low community uptake of the HAT screening in endemic districts in the Republic of Congo. Methods: a cross-sectional survey was carried out during a sensitisation campaign about HAT in the districts of Mpouya, Ngabé and Loudima, which are endemic for the disease. After signing the informed consent form, participants were organized into groups of 10 for focus group discussions (FGDs). A list of questions was used for guiding the discussion, addressing understanding of the disease and reasons for refusing screening. Results: out of 220 recruited individuals (corresponding to 22 FGDs), 58.6% were men. The majority of the respondents described HAT as a rural disease (48.2%) or as a witchcraft (22.3%). Among the clinical signs cited by the participants, sleep disorder (40%) was the most common answer, followed by prolonged fever (19.5%) and madness (14.1%). The main reasons for non-adherence to HAT screening was the fear of lumbar puncture (45.9%) and stigmatisation (22.3%). Conclusion: the findings of this study suggest that more effort should be put into raising awareness of HAT and the benefits of screening amongst the Congolese population, in order to strengthen the national disease control program.

Prevalence of non-Plasmodium falciparum species in southern districts of Brazzaville in The Republic of the Congo.

BACKGROUND: Although Plasmodium falciparum infection is largely documented and this parasite is the main target for malaria eradication, other Plasmodium species persist, and these require more attention in Africa. Information on the epidemiological situation of non-P. falciparum species infections is scarce in many countries, including in the Democratic Republic of the Congo (hereafter Republic of the Congo) where malaria is highly endemic. The aim of this study was to determine the prevalence and distribution of non-P. falciparum species infections in the region south of Brazzaville. METHODS: A cross-sectional survey was conducted in volunteers living in rural and urban settings during the dry and rainy seasons in 2021. Socio-demographic and clinical parameters were recorded. Plasmodium infection in blood samples was detected by microscopic analysis and nested PCR (sub-microscopic analysis). RESULTS: Of the 773 participants enrolled in the study, 93.7% were from the rural area, of whom 97% were afebrile. The prevalence of microscopic and sub-microscopic Plasmodium spp. infection was 31.2% and 63.7%, respectively. Microscopic Plasmodium malariae infection was found in 1.3% of participants, while sub-microscopic studies detected a prevalence of 14.9% for P. malariae and 5.3% for Plasmodium ovale. The rate of co-infection of P. malariae or P. ovale with P. falciparum was 8.3% and 2.6%, respectively. Higher rates of sub-microscopic infection were reported for the urban area without seasonal fluctuation. In contrast, non-P. falciparum species infection was more pronounced in the rural area, with the associated risk of the prevalence of sub-microscopic P. malariae infection increasing during the dry season. CONCLUSION: There is a need to include non-P. falciparum species in malaria control programs, surveillance measures and eradication strategies in the Republic of the Congo.

Dengue virus serological markers among potential blood donors: an evidence of asymptomatic dengue virus transmission in Cameroon.

INTRODUCTION: the risk of dengue virus or its antibodies which can be transmitted through blood transfusion by asymptomatic individuals infected, has been a major concern all over the world. Dengue is an endemic disease in sub-Saharan Africa, particularly in Cameroon. The purpose of this study is to determine the frequency of dengue virus (DENV) infection among potential blood donors at Yaounde Jamot Hospital. METHODS: serum samples were collected from 310 potential adult blood donors aged 18-57 years, who signed a written informed consent and completed the questionnaire between March 2019 and August 2019. This serum is used to screen for the presence of serological markers of DENV infection (NS1, IgM and IgG) using immunochromatographic tests (Zhuhai Encode Medical Engineering Co., Ltd, China). IgM/IgG positive samples were confirmed by enzyme-linked immunosorbent assays (ELISA). RESULTS: the overall prevalence was 24.8% among potential blood donors were subdivided as follows: 4.5% (14/310), 12.3% (38/310) and 6.1% (19/310) showed mono-positivity to DENV-NS1 antigen, anti-DENV IgM and anti-DENV IgG antibodies respectively. 1.9% (6/310) of potential blood donors showed dual positivity to anti-DENV IgM antibodies and anti-DENV IgG antibodies. The presence of DENV-NS1 antigen show asymptomatic viremia of dengue at the time of donation, while the presence of IgG antibodies reflects the high endemicity of dengue disease in the city of Yaoundé. CONCLUSION: these findings demonstrate the high level of risk of the DENV transmission among potential blood donors to needy recipients, underscoring the importance of establishing dengue fever blood screening in different services and blood collection units in Cameroon to improve safety transfusion and control the dissemination of the DENV.

Performance of the BD FACSPresto near to patient analyzer in comparison with representative conventional CD4 instruments in Cameroon.

BACKGROUND: In the context of scaling the viral load in resource limited settings, following HIV infected patient's adults and children with CD4+ T-lymphocyte count still very important in settings where the decentralization of treatment still has some challenges. Effective HIV monitoring in these resource-constrained settings needs affordable and reliable CD4+ T lymphocytes enumeration methods. We investigated the validity of a BD FACSPresto POC which is a dedicated system for enumeration that uses immunofluorescent technologies. In this study, we have assessed the sensitivity, specificity and correlation between most representative flow cytometry instruments present in Cameroon with more than 5000 CD4 T cells tests per year including FACSCalibur, FACSCount, and PIMA POC from Becton-Dickinson and ALERE respectively. METHODS: 268 patients aged from 1 to 72 years old were enrolled and included in the study after inform consent. The BD FACSPresto POC CD4+ T cell technology was placed at CIRCB and operated by technician staff. HIV infected patients were from Chantal BIYA international reference Center (CIRCB), Centre de Sante Catholique de NKOLODOM, Centre de Sante Catholique de BIKOP and CASS de Nkolndongo-Yaounde We compared the accuracy of the BD FACSPresto and three existing reference technologies with more than 5000 tests per year like FACSCalibur, FACSCount and PIMA according to the number of CD4 test done per year and their repartition in the country. Bland-Altman method and correlation analysis were used to estimate mean bias and 95% limits of agreement and to compare the methods, including analysis by subgroup of participant gestational age. In addition sensitivity and specificity were determined. Statistical significance was set at P-value < 0.05. RESULTS: The BD FACSPresto POC system has excellent precision, accuracy and linearity for CD4+ T lymphocytes enumeration. Good correlations were obtained between the BD FACSPresto poc system and other single platform methods. Bland-Altman plots showed interchangeability between two machines mean bias BD-FACSPresto vs PIMA = - 126,522(- 161,221 to - 91,822) BD-FACSPresto vs FACSCount = - 38,708 (- 58,935 to - 18,482) and FACSPresto vs FACSCALIBUR = 0.791(- 11,908 to 13,491). Mean difference with Absolute CD4+ T-lymphocyte values obtained from the BD FACSPresto system correlated well with PIMA, FACSCount, and FACSCalibur method with R2 equal to 0.88, 0.92 and 0.968 respectively with P < 0.001 for all. The mean comparison between values obtained from BD FACSPresto with PIMA, FACSCount, and FACSCalibur using paired T test give P = 0.17, P = 0.5 and P = 0.6 respectively meaning that there is no significant differences between values obtained with BD FACSPresto and PIMA, FACSCount or FACSCalibur CD4 enumeration machines. Further analysis revealed close agreement between all the three instruments with no significant difference between the forth methods (P = 0.91). CONCLUSION: This BD-FACSPresto POC system is a simple, robust and reliable system for enumeration of absolute and percentage of CD4+ T-lymphocytes especially suitable for remote areas with limited resources. Having one BD-FACSPresto POC system easy to use, should reduce the cost and thus increase and improved access to CD4 testing for HIV infected patients in resource-constrained countries. BD-FACSPresto POC CD4 will enable reduction in patient time and improve the overall quality of ART service count and may improve test access in remote areas. This technology can allow for greater decentralization and wider access to CD4 testing and ART.

In vivo targeting of protein antigens to dendritic cells using anti-DEC-205 single chain antibody improves HIV Gag specific CD4+ T cell responses protecting from airway challenge with recombinant vaccinia-gag virus.

INTRODUCTION: Targeting antigens to dendritic cells (DCs) in vivo via a DC-restricted endocytic receptor, DEC205, has been validated to enhance immunity in several vaccine platforms. Particularly atttractive is selected delivery of proteins to DCs in vivo because it enables proteins to be more immunogenic and provides a cheaper and effective way for repeated immunizations. METHODS: In this study, we tested the efficacy of a single chain antibody to DEC205 (scDEC) to deliver protein antigens selectively to DCs in vivo and to induce protective immunity. RESULTS: In comparison to soluble Ovalbumin (OVA) antigen, when recombinant scDEC:OVA protein was injected subcutaneously (s.c.) into mice, the OVA protein was selectively presented by DCs to both TCR transgenic CD8+ and CD4+ T cells approximately 500 and 100 times more efficient than soluble OVA, respectively, and could persist for seven days following s.c. injection of the scDEC205:OVA. Similarly selective targeting of HIV Gag P24 to DCs in vivo using scDEC-Gag protein plus polyICLC vaccine resulted in strong, long lasting, polyfuntional CD4+ T cells in mice which were protective against airway challenge by a recombinant vaccinia-gag virus. CONCLUSION: Thus targeting protein antigens to DCs using scDEC can be used either alone or in combination with other strategies for effective immunization.

Filaria specific antibody response profiling in plasma from anti-retroviral naïve Loa loa microfilaraemic HIV-1 infected people.

BACKGROUND: In West and Central Africa areas of endemic Loa loa infections overlap with regions of high prevalence of human immunodeficiency virus type 1 (HIV-1) infections. Because individuals in this region are exposed to filarial parasites from birth, most HIV-1 infected individuals invariably also have a history of filarial parasite infection. Since HIV-1 infection both depletes immune system and maintains it in perpetual inflammation, this can hamper Loa loa filarial parasite mediated immune modulation, leading to enhanced loaisis. METHODS: In this study we have assessed in plasma from asymptomatic anti-retroviral (ARV) naïve Loa loa microfilaraemic HIV-1 infected people the filarial antibody responses specific to a filariasis composite antigen consisting of Wbgp29-BmR1-BmM14-WbSXP. The antibody responses specific to the filariasis composite antigen was determined by enzyme linked immunosorbent assay (ELISA) in plasma from ARV naïve Loa loa microfilaraemic HIV-1 infected participants. In addition the filarial antigen specific IgG antibody subclass profiles were also determined for both HIV-1 positive and negative people. RESULTS: Both Loa loa microfilaraemic HIV-1 positive and negative individuals showed significantly higher plasma levels of IgG1 (P < 0.0001), IgG2 (P < 0.0001) and IgM (P < 0.0001) relative to amicrofilaraemic participants. A significant increase in IgE (P < 0.0001) was observed exclusively in Loa loa microfilaraemic HIV-1 infected people. In contrast there was a significant reduction in the level of IgG4 (p < 0.0001) and IgG3 (P < 0.0001) in Loa loa microfilaraemic HIV-1 infected individuals. CONCLUSIONS: Loa loa microfilaraemia in ARV naïve HIV-1 infected people through differential reduction of plasma levels of filarial antigen specific IgG3, IgG4 and a significant increase in plasma levels of filarial antigen specific IgE could diminish Loa loa mediated immune-regulation. This in effect can result to increase loaisis mediated immunopathology in antiretroviral naive HIV-1 infected people.

Dendritic cell targeted HIV-1 gag protein vaccine provides help to a recombinant Newcastle disease virus vectored vaccine including mobilization of protective CD8+ T cells.

INTRODUCTION: Recombinant Newcastle Disease virus (rNDV) vectored vaccines are safe mucosal applicable vaccines with intrinsic immune-modulatory properties for the induction of efficient immunity. Like all viral vectored vaccines repeated inoculation via mucosal routes invariably results to immunity against viral vaccine vectors. To obviate immunity against viral vaccine vectors and improve the ability of rNDV vectored vaccines in inducing T cell immunity in murine air way we have directed dendritic cell targeted HIV-1 gag protein (DEC-Gag) vaccine; for the induction of helper CD4+ T cells to a Recombinant Newcastle disease virus expressing codon optimized HIV-1 Gag P55 (rNDV-L-Gag) vaccine. METHODS: We do so through successive administration of anti-DEC205-gagP24 protein plus polyICLC (DEC-Gag) vaccine and rNDV-L-Gag. First strong gag specific helper CD4+ T cells are induced in mice by selected targeting of anti-DEC205-gagP24 protein vaccine to dendritic cells (DC) in situ together with polyICLC as adjuvant. This targeting helped T cell immunity develop to a subsequent rNDV-L-Gag vaccine and improved both systemic and mucosal gag specific immunity. RESULTS: This sequential DEC-Gag vaccine prime followed by an rNDV-L-gag boost results to improved viral vectored immunization in murine airway, including mobilization of protective CD8+ T cells to a pathogenic virus infection site. CONCLUSION: Thus, complementary prime boost vaccination, in which prime and boost favor distinct types of T cell immunity, improves viral vectored immunization, including mobilization of protective CD8+ T cells to a pathogenic virus infection site such as the murine airway.

Seroprevalence of dengue virus among children presenting with febrile illness in some public health facilities in Cameroon.

INTRODUCTION: A routine diagnosis of Dengue virus (DENV) infection is not usually conducted in hospitals. Because symptoms overlap, many potential febrile illnesses due to DENV may be confused for malaria, typhoid or paratyphoid (enteric) fever. The absence of data on DENV exposure rates among children attending health facilities could undermine management of this disease. This study aimed to investigate the seroprevalence of dengue virus infection in children presenting febrile illness in some public health facilities in Cameroon. METHODS: A cross-sectional study was performed in children ≤ 15 years attending seven urban and three semi-urban public hospitals of Cameroon. From each volunteer, 2ml of whole blood was collected and tested for dengue virus IgM, malaria (Pf/Pan antigens) and enteric fever (Typhoid IgM) using rapid diagnostic tests (RDT); in order to allow the healthcare workers to quickly put the positive cases under appropriate treatment. Positive cases of dengue virus infection were confirmed by indirect ELISA. Data analysis were performed using the statistical package for social sciences software, version 22.1. RESULTS: A total of 961 children were enrolled in the study and 492 (51.2%) were infected with at least one of the three pathogens. Overall, DENV IgM seroprevalence among febrile children was 14.4% (138/961). About 390 (40.6%) and 22 (2.3%) had malaria (Pf/Pan Ag) and enteric fever (Typhoid IgM) respectively. Co-infection with dengue virus was found in 51 (5.3%) participants. The dengue virus IgM seroprevalence was higher in Bankim (19.3%), Ntui (18.3%) and Douala (18.2%). CONCLUSION: Dengue virus infection seroprevalence appears to be low in children presenting with febrile illness in the studied health centres in Cameroon but call for more attention and research to further characterise the circulating strains of the dengue virus.

Phenotypic characterization of regulatory T cells from antiretroviral-naive HIV-1-infected people.

Regulatory T (Treg) cells play a key role in dampening excessive immune activation. However, antiretroviral therapy (ART) -naive HIV-1 infection maintains the immune system in a sustained state of activation that could alter both Treg cell surface markers and functions. As Treg cell surface markers are directly linked to their functions the overall objective of this study was to determine how ART-naive HIV infection affects the phenotypic properties of Treg cells. Our data showed that in ART-naive HIV-1 infection, Treg cells are dominated by effector (CD45RA+  CD27-  CCR7- CD62L- ) and effector memory (CD45RA-  CD27-  CCR7-  CD62L- ) cells. In contrast Treg cells from HIV-negative individuals were mainly naive (CD45RA+  CD27+  CCR7+  CD62L+ ) and central memory (CD45RA- CD27+  CCR7+  CD62L+ ) cells. Whereas effector and effector memory Treg cells showed enhanced expression of CD39 (P < 0·05), CD73 (P < 0·001), HLA-DR and CD38 (P < 0·001); naive and central memory Treg cells showed a significant reduction in the expression of these markers. Overall Treg cell frequencies within total CD4+ T cells correlated positively with plasmatic HIV-1 viral load. As increased viral load is associated with augmented CD4+ T-cell destruction; this could suggest a resistance of peripheral Treg cells to HIV-1 destruction. Hence the modulation of Treg cell phenotype and frequencies could be considered in designing immunotherapeutic strategies targeting immune system restoration during HIV-1 infection.

The Effect of Antiretroviral Naïve HIV-1 Infection on the Ability of Natural Killer Cells to Produce IFN-γ upon Exposure to Plasmodium falciparum-Infected Erythrocytes.

BACKGROUND: In sub-Saharan Africa, intense perennial Plasmodium species transmission coincides with areas of high prevalence of the human immunodeficiency virus type 1 (HIV) infection. This implies that antiretroviral naïve HIV-infected people living within these regions are repeatedly exposed to Plasmodium species infection and consequently malaria. Natural killer (NK) cells are known to contribute to malaria immunity through the production of IFN-γ after exposure to Plasmodium falciparum-infected erythrocytes (infected red blood cells [iRBC]). However, in antiretroviral naïve HIV-1 infection, these functions could be impaired. In this study we assess the ability of NK cells from antiretroviral naïve HIV-1-infected people to respond to iRBC. METHOD: Magnetically sorted NK cells from antiretroviral naïve HIV-1-infected people were tested for their ability to respond to iRBC following in vitro coculture. NK cell IFN-γ production after coculture was measured through multiparametric flow cytometry analysis. RESULTS: Our data show a significant reduction (p = 0.03) in IFN-γ production by NK cells from antiretroviral naïve HIV-1-infected people after coculture with iRBCs. This was in contrast to the NK cell response from healthy controls, which demonstrated elevated IFN-γ production. NK cell IFN-γ production from untreated HIV-1-infected participants correlated inversely with the viral load (r = -0.5, p = 0.02) and positively with total helper CD4+ T-cell count (r = 0.4, p = 0.04). Thus, antiretroviral naïve HIV-1 infection can dampen NK cell-mediated immunity to P. falciparum infection in malaria-intense regions. This could in effect escalate morbidity and mortality in people chronically infected with HIV-1.

Impact of placental Plasmodium falciparum malaria on the profile of some oxidative stress biomarkers in women living in Yaoundé, Cameroon.

BACKGROUND: Impact of the pathophysiology of Plasmodium falciparum placental malaria (PM) on the profile of some oxidative stress biomarkers and their relationship with poor pregnancy outcomes in women remain unknown. METHODS: Between 2013 and 2014, peripheral blood and placenta tissue from 120 Cameroonian women at delivery were assessed for maternal haemoglobin and, parasitaemia respectively. Parasite accumulation in the placenta was investigated histologically. The levels of oxidative stress biomarkers Malondialdehyde (MDA), Nitric Oxide (NO), Superoxide dismutase (SOD), Catalase (CAT) and Gluthatione (GSH) in the supernatant of teased placenta tissues were determined by Colorimetric enzymatic assays. RESULTS: Parasitaemia was inversely related to haemoglobin levels and birth weight (P <0.001 and 0.012, respectively). The level of lipid peroxide product (MDA) was significantly higher in the malaria infected (P = 0.0047) and anaemic (P = 0.024) women compared to their non-infected and non-anaemic counterparts, respectively. A similar trend was observed with SOD levels, though not significant. The levels of MDA also correlated positively with parasitaemia (P = 0.0024) but negatively with haemoglobin levels (P = 0.002). There was no association between parasitaemia, haemoglobin level and the other oxidative stress biomarkers. From histological studies, levels of MDA associated positively and significantly with placenta malaria infection and the presence of malaria pigments. The levels of SOD, NO and CAT increased with decreasing leukocyte accumulation in the intervillous space. Baby birth weight increased significantly with SOD and CAT levels, but decreased with levels of GSH. CONCLUSIONS: Placental P. falciparum infection may cause oxidative stress of the placenta tissue with MDA as a potential biomarker of PM, which alongside GSH could lead to poor pregnancy outcomes (anaemia and low birth weight). This finding contributes to the understanding of the pathophysiology of P. falciparum placental malaria in women.

Placental malaria and modulation of immune and hormonal responses in Cameroonian women.

Adverse pregnancy outcomes place the lives of mother and new born babies in jeopardy, especially in Sub Saharan Africa. Although a well-balanced network of the pregnancy-associated hormones and lipid fractions is necessary for healthy pregnancy, the profiles of some of these biomarkers alongside those of some cytokines in relation to placental malaria (PM) and poor pregnancy outcomes are unknown. Therefore between 2013 and 2014, paired peripheral and placental blood samples were collected from 135 Cameroonian women at delivery. Parasitaemia was determined microscopically and haemoglobin levels using Coulter counter. Plasma levels of cytokines (IFN-γ, IL-1ß and IL-7) and pregnancy-associated hormones (17ß oestradiol and progesterone) were measured by ELISA and the levels of lipid fractions: total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglycerides (TG) determined by Colorimetric enzymatic methods. Parasitaemia was inversely related to parity, haemoglobin levels and birth weight (P≤0.019). While the levels of IFN-γ and cholesterol (total, HDL and LDL) were higher in peripheral plasma, those of IL-1ß, 17ß oestradiol, progesterone and triglyceride were higher in placental blood (P<0.001). Absence of PM was significantly associated with high plasma levels of IFN-γ, IL-7 and HDL-C and low plasma levels of 17ß oestradiol and TG. Moreover, IL-7 levels correlated positively and significantly with haemoglobin levels and with both peripheral and placental levels of progesterone. Baby birth weight increased with plasma levels of progesterone and HDL-C. Levels of IFN-γ correlated positively and significantly with HDL-C, but negatively with LDL-C; thus, might prevent pregnant women from atherogenic risk. Study of the inter-relationship between hormones, cytokines and lipids revealed that the association between IL-7 and progesterone and/or some lipid fractions followed inverse trends from that of IFN-γ. These results suggest that in PM, IFN-γ and IL-7 might protect against poor pregnancy outcomes, which decrease plasma levels of progesterone, maternal haemoglobin and HDL-C, leading to low birth weight. However, these cytokines may act differently with regards to progesterone and some lipid fractions. PM may also lower plasma levels of HDL-C and increase that of TG which is the most important risk factor for cardiovascular disorders and consequently poor pregnancy outcomes.