Céline Nguefeu Nkenfou

Depletion of macrophages in mice results in higher dengue virus titers and highlights the role of macrophages for virus control.

Monocytes and macrophages are target cells for dengue infection. Besides their potential role for virus replication, activated monocytes/macrophages produce cytokines that may be critical for dengue pathology. To study the in vivo role of monocytes and macrophages for virus replication, we depleted monocytes and macrophages in IFN‐αβγR knockout mice with clodronate liposomes before dengue infection. Although less virus was first recovered in the draining LN in the absence of macrophages, monocyte/macrophage depletion eventually resulted in a ten‐fold higher systemic viral titer. A massive infiltration of CD11b+CD11clowLy6Clow monocytes into infected organs was observed in parallel with increasing virus titers before viremia was controlled. Depletion of monocytes in the blood before or after local infection had no impact on virus titers, suggesting that monocytes are not required as “virus‐shuttles”. Our data provide evidence that systemic viremia is established independently of tissue macrophages present at the site of infection and blood monocytes. Instead, we demonstrate the importance of monocytes/macrophages for the control of dengue virus.

Intestinal parasitic infections in HIV infected and non-infected patients in a low HIV prevalence region, West-Cameroon.

The magnitude of intestinal parasitic infection in acquired immunodeficiency syndrome patients requires careful consideration in the developing world where poor nutrition is associated with poor hygiene and several tropical diseases. However, there have been very few studies addressing this issue in Cameroon. This study was conducted to determine the prevalence of intestinal parasitosis in HIV/AIDS patients in Dschang -Cameroon. Stool and blood specimens from HIV/AIDS patients and control group were screened respectively for intestinal parasites and for HIV antibodies. Intestinal parasites were identified using direct microscopy, formalin-ether concentration and Ziehl Neelsen methods. Out of 396 participants recruited among patients consulting at hospital, 42 (10.6%) were HIV positive, thirty of them treatment naïve. The overall prevalence of intestinal parasites was 14.64%. Out of 42 HIV/AIDS patients, 59.5% (25/42) were infected with intestinal parasites, while only 9.32% (33/354) of the HIV negative patients were infected with intestinal parasites. The parasites detected in our study population included Crystosporidium parvum (2.53%), Entamoeba histolytica (7.52%), Entamoeba coli (4.04%), Giardia lamblia (0.25%), Trichuris trichura (0.25%), Strongyloides stercoralis (0.25%) and Taenia spp. (0.25%). In the HIV infected group, Crystosporidium parvum (19.04%), Entamoeba histolytica (19.04%), Entamoeba coli (21.42%), Giardia lamblia (2.38%), Strongyloides stercoralis (0.25%) and Taenia spp. (0.25%) were found. Crystosporidium parvum was found to be significantly higher in HIV/AIDS patients than in controls (P<0.05). Multivariate analysis showed that the HIV status and the quality of water were the major risk factors for intestinal parasitosis. Routine examinations of stool samples for parasites would significantly benefit the HIV patients by contributing in reducing morbidity and improving the efficiency of antiretroviral treatment. Even after the introduction of free anti-retroviral drugs, opportunistic intestinal infections are still a threat. HIV patients should be screened routinely for intestinal parasites and treated for their overall well being.

Distribution of CCR5-Delta32, CCR5 promoter 59029 A/G, CCR2-64I and SDF1-3'A genetic polymorphisms in HIV-1 infected and uninfected patients in the West Region of Cameroon

BackgroundGenetic variants of the genes encoding Human Immunodeficiency Virus-1 (HIV-1) co-receptors and their ligands, like CC-Chemokine Receptor 5 delta 32 mutation (CCR5-Delta32), CCR5 promoter A/G (Adenine/Guanine), CC-Chemokine Receptor 2 mutation 64 isoleucine (CCR2-64I) and the Stromal cell-derived Factor 3’A mutation (SDF1-3’A), are involved in the susceptibility to HIV-1 infection and progression. The prevalence of these mutations varies by Region. However, little is known about their distribution in the population of Dschang, located in the West Region of Cameroon. The prevalence of HIV in the West Region of Cameroon is lower than elsewhere in Cameroon. The objectives of this study were to determine the distribution of four AIDS Related Gene (ARG) variants in HIV-infected and non-infected population of Cameroon especially in the West Region and to estimate the contribution of these variants to the susceptibility or resistance to HIV infection. We also aimed to evaluate the effectiveness of genotyping using dried blood spot (DBS) samples.MethodsA total of 179 participants were recruited from two hospitals in Dschang in the West Region of Cameroon. Their genotypes for CCR5-Delta32, CCR5 promoter 59029A/G, CCR2-64I and SDF1-3’A were analyzed using polymerase chain reaction (PCR) and restriction fragment length polymorphisms.ResultsA total of 179 participants were enrolled in the study. Among them, 32 (17.9%) were HIV positive and 147 (82.1%) were HIV negative. The allelic frequencies of these genes were: 0%, 49.72%, 17.6% and 100% respectively for CCR5-Delta32, CCR5 promoter 59029A/G, CCR2-64I and SDF1-3’A. No individual was found to carry the CCR5-Delta 32 mutation. All participants recruited were heterozygous for the SDF1-3’A allele.ConclusionOur data suggest that the CCR5-Delta32 cannot account for the protection as it was completely absent in our population. SDF1-3’A variants, may be in association with other polymorphisms, may account for the overall protection from HIV-1 infection in participants recruited as everyone carries this allele. The CCR5 promoter 59029 G/G genotype may be associated with the risk for HIV-1 infection in this population, while the CCR2-64I (A/A genotype) may account for the protection against HIV infection. The results of genotyping from fresh blood and DBS were comparable.

HIV-1 Early Infant Diagnosis is an Effective Indicator of the Prevention of Mother-to-Child Transmission Program Performance: Experience from Cameroon.

BACKGROUND Despite improvement in HIV prevention of mother-to-child transmission (PMTCT), there are still over 1,500 African infants newly infected daily. PMTCT elimination requires antiretroviral therapy (ART) throughout pregnancy and breastfeeding periods, while early infant diagnosis (EID) of HIV implies early treatment for those infected. Our study aimed at assessing the utility of EID program data in evaluating the implementation of PMTCT program in Cameroon, and in identifying the efficacy of existing PMTCT interventions and breastfeeding options on the events of HIV vertical transmission. METHODS A study was conducted from 2010-2011 using PMTCT data from EID sites of six regions of Cameroon. PMTCT ARV regimens, breastfeeding options, and the childs HIV DNA-polymerase chain reaction (PCR) results were recorded. Statistical analyses were performed using Mann Whitney U and Fisher exact tests, with p<0.05 considered significant. RESULTS A total of 2,505 mother-child pairs received ART, resulting is 4.3% (93) vertical transmission, against 31.3% (284/906) among mother-child pairs without exposure to any PMTCT intervention; p<0.00001. A statistically significant difference (p<0.00001) was also found between formula feeding (FF) (5.9%) versus exclusive breastfeeding (EBF) (12.5%), as well as between EBF versus mixed feeding (MF) (30%). With FF, when both mother-child pairs received PMTCT, only 2.9% (47/1603) vertical transmission was recorded versus 19.9% (48/241) for mother-child pairs without intervention; p<0.00001. Transmission rates were similar across infant age range [2.7% (10/376) for age ≤6 weeks, versus 2.5% (43/1807) for age >6 weeks-6 months]. Interestingly, babies aged 6 weeks receiving FF showed a significantly lower transmission rate (3.2%, 9/277) as compared to their counterparts with EBF (7.7%, 12/156); p<0.00001. CONCLUSION Using EID dataset, it appears that considerable reduction in HIV MTCT may be achievable through access to ARV (option B+) and adequate infant feeding option (especially FF) in Cameroon. EID programme is therefore an effective routine approach for PMTCT programme evaluation in resource-limited settings.

Anti-mycobacterial activity of polyketides from Penicillium sp. endophyte isolated from Garcinia nobilis against Mycobacteriumsmegmatis.

Objective/background: According to estimates by the World Health Organization, there were 9.6 million new tuberculosis (TB) cases in 2014: 5.4 million among men, 3.2 million among women, and 1.0 million among children. There were also 1.5 million TB deaths. Although there are potent anti-TB molecules, the misuse of these drugs in addition to inconsistent or partial treatment have led to the development of multidrug-resistant TB and extensively drug-resistant TB. It is established that plants harbor microorganisms, collectively known as endophytes, which also produce metabolites. Exploring the as-yet untapped natural products from the endophytes increases the chances of finding novel and active compounds. The present study was aimed to investigate the antimycobacterial activity of the crude extract and compounds isolated from Penicillium sp. endophyte associated with Garcinia nobilis against Mycobacterium smegmatis. Methods: Liquid culture obtained from the fermentation of Penicillium sp. was extracted using ethylacetate and the liquid chromatography–mass spectrometry monitored fractionation of crude extracts yielded six compounds. Their structures were elucidated with spectroscopic analyses including two-dimensional nuclear magnetic resonance, high resolution mass spectrometry by dereplication using Antibase, and by comparison to literature data. All compounds and the crude extract from the liquid medium were evaluated for their antimycobacterial activity against M. smegmatis. Results: In this study, the activity of penialidins A–C (1–3), citromycetin (4), p-hydroxy phenyl glyoxalaldoxime (5), and Brefeldin A (6) were tested against nonpathogenic M. smegmatis. Penialidin C was the most active compound with a minimum inhibitory concentration of 15.6μg/mL. Conclusion: Isolated compounds from Penicillium sp. harbored in G. nobilis exhibited promising antimycobacterial activity against M. smegmatis thus supporting the immensity of the potential of antimycobacterial drug discovery from endophytes from medicinal plants. Penialidin C could further be investigated for antimycobacterial drug development.

The pros and cons of the QuantiFERON test for the diagnosis of tuberculosis, prediction of disease progression, and treatment monitoring.

Objective/Background: Tuberculosis (TB) is a re-emerging disease with the advent of human immunodeficiency virus/AIDS infections. Discovered in 1959, diagnosed by various approaches and treated with antibiotics, the treatment of TB infection still poses public health concerns. Many cases of resistance and cross-resistance are observed. Diagnosis by culture, which is considered as the standard method, takes too long (20–30days) and is not suitable for extrapulmonary TB. QuantiFERON test, which is an indirect immunoassay based on blood, was developed. Much hope was placed in this new approach because it is based on blood, and many research teams have used it. We discuss the results of these different research groups who have used QuantiFERON for diagnosis, prediction of disease progression, or monitoring patients during the treatment of TB. Methods: rticles published in PubMed and documents published on Google were searched with the keywords: diagnosis and TB and QuantiFERON; TB and QuantiFERON and therapeutic monitoring; interferon-γ release assay; disease progression. These articles were read and analyzed. Results: The results were controversial with regards to using the QuantiFERON test for the diagnosis of TB according to the study population (ethnic group, bacillus Calmette–Guérin vaccine use) and according to the state of the immune system of the people studied (human immunodeficiency virus immunosuppression in cancer medication, hypertension). Also, research findings were controversial with regards to using QuantiFERON for monitoring TB patients on anti-TB medications. Also, the predictive positive value for the progression to TB among immigrant close contacts of both interferon-γ release assays was not better than that of the tuberculin skin test. Conclusion: The QuantiFERON has advantages and limitations depending on the type of population studied. Recommendations are made to improve the sensitivity and specificity and to differentiate between latent and active TB by adding other specific proteins in the Mycobacterium tuberculosis antigen cocktail.

In vitro antimycobacterial activity of six Cameroonian medicinal plants using microplate alamarBlue assay.

OBJECTIVE/BACKGROUND The latest incidence of tuberculosis (TB) (per 100,000 people) in Cameroon was 243.00 as of 2011. Over the past 21 years, the value for this indicator has fluctuated between 112.00 in 1990 and 320.00 in 2003. Worldwide, this incidence has also increased, bringing back TB as a reemerging disease. On the same note, resistance to anti-TB drugs has increased, urging the search for new molecules. METHODS This study was carried out to evaluate the antimycobacterial activity of six medicinal plants on the virulent strain, H37Rv, using the microplate alamarBlue assay. Mycobacterium tuberculosis (H37Rv strain) was incubated with decreased concentrations of six plant extracts, ranging from 250 μg/mL to 31.25 μg/mL. After 7 days of incubation at 37 °C, the effects of these plant extracts on the viability of the mycobacteria were evaluated. For each plant extract, the minimal inhibitory concentration was determined. RESULTS The results showed that the compounds MBC1, MBC24, MBC68, MBC81, MBC117, and MBC118 were the best candidates with minimal inhibitory concentrations of 31.25, 62.5, 125, 62.5, and 125 μg/mL, respectively. CONCLUSION These results confirm and validate the traditional use of these plants to treat respiratory diseases, which could be good sources and alternatives of plant metabolites for anti-TB-drug development.

Bioinformatics Probing of Tissue-Specific MiRNAs Overexpressed in Active Tuberculosis Reveals Induction of Multiple Cancer Pathways

This study attempts to discern the genes and pathways of tissue-specific miRNAs overexpressed in active tuberculosis (TB). The chosen 11 miRNAs were grouped into serum (S1), sputum (S2), and peripheral blood mononuclear cell (PBMC) (S3) classes. DIANA-miRPath v3 was used for the bioinformatics analyses. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) practices were used to pinpoint the key regulatory channels and functional annotations associated with the latent state. ECMreceptor interaction, transcriptional misregulation in cancer, nonsmall cell lung cancer, proteoglycans, and pathways in cancer were identified as the prime pathways in TB-related miRNAs. S1 and S3 transcripts showed the unifying ECM-receptor interaction with collagen (COL) and laminin (LAM) genes common to both datasets. Further research on these cancer-related cascades could provide mechanistic and therapeutic insights into TB pathophysiology.

Expression Level of Plasma Soluble Toll like Receptor 2 and 6 in the Mother toChild Transmission of Human Immunodeficiency Virus Type 1

Background and context: Dysregulation of the immune system by the Human immunodeficiency virus (HIV) has an impact on innate immune components such as Toll-like receptors (TLRs). Objective: We looked at the plasma concentration of soluble TLR2 and sTLR6 in mother-to-child transmission. Methods: Two hundred and eighty three mothers with their newborn were recruited. Mothers were classified into five groups: transmitter with prevention (TWP), transmitter without prevention (TWDP), non-transmitter with prevention (NTWP), non-transmitter without prevention (NTWDP) and controls. Mothers’ blood samples were collected in EDTA tubes. Levels of sTLR2/6 were determined using sandwich enzyme-linked immunosorbent assays. HIV status of new-born was determined using PCR-DNA on dried blood spots. Results: HIV infected mothers have a statistically higher level of sTLR2 than HIV non-infected mothers (p=0.001). The highest concentration was found in the NTWDP >TWP >NTWP >TWDP. There was a significant difference between all the medians comparing groups two by two. For sTLR6 there was neither a significant difference (p=0.156) between HIV infected and non-infected mothers, nor between groups. The median concentration was higher in NTWDP > NTWP > TWP > TWDP. Conclusion: sTLR2 and sTLR6 plasma concentration may be associated to the prevention of mother-to-child transmission. But antiretroviral treatment could also dim down this protective effect.

Chronic obstructive pulmonary disease (COPD) : neutrophils, macrophages and lymphocytes in patients with anterior tuberculosis compared to tobacco related COPD

ObjectiveThe inflammatory profile of chronic obstructive pulmonary disease (COPD) related to tobacco is known in certain studies while that of the post tuberculosis form is not yet known. This study aimed to evaluate the levels of neutrophils, macrophages and lymphocytes cells in sputum of COPD patients with history of smoking or anterior tuberculosis. Enumeration of cells in samples was analyzed using standard microscopy.ResultsWe enrolled 92 participants, 46 (50%) were COPD subjects comprising 22 (47.83%) smokers and 24 (52.17%) with anterior tuberculosis while 46 (50%) healthy persons constituted the control group. The levels of neutrophils, lymphocytes and monocytes were statistically higher in COPD patients compared to the control group with p-values of 0.0001 respectively. Neutrophils levels were higher in COPD patients with history of tobacco than in COPD patients with anterior tuberculosis with a mean rate of 4.72 × 106/ml and 2.48 × 106/ml respectively (p = 0.04). The monocytes and lymphocytes levels were not statistically different between the two sub-groups of COPD patients with p-value of 0.052 and 0.91 respectively. Neutrophils are the only inflammatory cells that were significantly higher in COPD patients with history of smoking as compared to COPD patients with anterior tuberculosis.