Diagnosis of seeds supply of leafy vegetables in Yaoundé, Cameroon

The traditional leafy vegetables play a major role in the Cameroonian diet. In the metropolitan zone of Yaoundé, these vegetables are produced year round in family and commercial exploitations. The quality of the seeds, their mode of production and their system of distribution are little known. With the aim to better understand the seed system of traditional  vegetables, a study on the supply, the production and the quality of these seeds was carried out. The data were collected using questionnaires on a sample of 133 traditional leafy vegetable producers of the urban and peri-urban zone of Yaoundé. The data were analyzed using SNAP 9  software. The study showed that the most produced species are amaranth (Amaranthus cruentus), nightshade (Solanum scabrum) and jute mallow (Corchorus olitorius). The market-gardeners are influenced in their choice of vegetable to cultivate by the preference of the customers (85.7% of the respondents) and the productivity of the cultivars (66.2% of the  respondents). More than 40% of the respondents buy seeds in the  markets while 7.5% buy seed from other producers and 10.5% in the agricultural inputs stores. About half (47.4%) of the respondents produce seeds by leaving plants in the field after the first or the second harvest while 36.8% of the market-gardeners select the most vigorous plants for seed production. On average, 58.7% of respondents preserve the seeds in hermetically closed bottles and plastic bag. Storage on field is practiced by a significant part of market-gardeners (41.4%). A total of 79.7% of the producers reported constraints with the produced seeds. Poor seed  germination (81.1% of respondents) and the non uniformity of the seed (48.1% of the producers) were reported as the major constraints. The principal source of seed supply in the metropolitan zone of Yaoundé is the self production with rudimentary production and storage techniques subject to many qualitative constraints.Key words: leafy, vegetables, seeds, supply, qualit

Seroepidemiology of Toxoplasmosis in Pregnant Women Attending the University Teaching Hospital in Yaounde, Cameroon

Purpose: The study was carried out to investigate the epidemiology and associated toxoplasmosis predisposing risk factors in Cameroon. Methods: The survey took place at the Yaounde University Teaching Hospital from May to June 2008. Serum samples were collected from 110 pregnant women attending the ante natal clinic using aseptic techniques after obtaining informed consent. The samples were analysed using toxo-lgG immunocomb and toxo-IgM “capture” ELISA. A structured questionnaire was used to collect information on predisposing risk factors for toxoplamosis from each patient. Data was analysed on Epi-Info using confidence intervals and chi-square statistic test. Results: The average age of the women was 27.9+5.8years and the mean gestational age was 4.1+0.2months. The overall IgG seroprevalence was 65.5% {95% CI: 53.7-71.7%} and that of IgG and IgM co-infection was 2.7%. The seroprevalence was 75% in the first trimester, 60.6% in the second trimester and 50% in the third trimester. No statistically significant relationships were established between anti-toxoplasma IgG and IgM antibodies and abortion history, meat consumption, potable water sources, cat ownership and age. Conclusion: The prevalence of IgG antibodies to Toxoplasma gondii is high and the first trimester in pregnancy carries the highest risk. All pregnant women should be screened for toxoplasmosis and educated on predisposing risk factors during antenatal visits.Keywords: Toxoplasma gondii, Pregnancy, IgG, IgM, Prevalenc

HIV/SIV Infection Primes Monocytes and Dendritic Cells for Apoptosis

Subversion or exacerbation of antigen-presenting cells (APC) death modulates host/pathogen equilibrium. We demonstrated during in vitro differentiation of monocyte-derived macrophages and monocyte-derived dendritic cells (DCs) that HIV sensitizes the cells to undergo apoptosis in response to TRAIL and FasL, respectively. In addition, we found that HIV-1 increased the levels of pro-apoptotic Bax and Bak molecules and decreased the levels of anti-apoptotic Mcl-1 and FLIP proteins. To assess the relevance of these observations in the context of an experimental model of HIV infection, we investigated the death of APC during pathogenic SIV-infection in rhesus macaques (RMs). We demonstrated increased apoptosis, during the acute phase, of both peripheral blood DCs and monocytes (CD14+) from SIV+RMs, associated with a dysregulation in the balance of pro- and anti-apoptotic molecules. Caspase-inhibitor and death receptors antagonists prevented apoptosis of APCs from SIV+RMs. Furthermore, increased levels of FasL in the sera of pathogenic SIV+RMs were detected, compared to non-pathogenic SIV infection of African green monkey. We suggest that inappropriate apoptosis of antigen-presenting cells may contribute to dysregulation of cellular immunity early in the process of HIV/SIV infection

The macrophage in HIV-1 infection: From activation to deactivation?

Macrophages play a crucial role in innate and adaptative immunity in response to microorganisms and are an important cellular target during HIV-1 infection. Recently, the heterogeneity of the macrophage population has been highlighted. Classically activated or type 1 macrophages (M1) induced in particular by IFN-γ display a pro-inflammatory profile. The alternatively activated or type 2 macrophages (M2) induced by Th-2 cytokines, such as IL-4 and IL-13 express anti-inflammatory and tissue repair properties. Finally IL-10 has been described as the prototypic cytokine involved in the deactivation of macrophages (dM). Since the capacity of macrophages to support productive HIV-1 infection is known to be modulated by cytokines, this review shows how modulation of macrophage activation by cytokines impacts the capacity to support productive HIV-1 infection. Based on the activation status of macrophages we propose a model starting with M1 classically activated macrophages with accelerated formation of viral reservoirs in a context of Th1 and proinflammatory cytokines. Then IL-4/IL-13 alternatively activated M2 macrophages will enter into the game that will stop the expansion of the HIV-1 reservoir. Finally IL-10 deactivation of macrophages will lead to immune failure observed at the very late stages of the HIV-1 disease

A look behind closed doors: interaction of persistent viruses with dendritic cells.

International audiencePersistent infections with HIV, hepatitis B virus and hepatitis C virus are major causes of morbidity and mortality worldwide. As sentinels of the immune system, dendritic cells (DCs) are crucial for the generation of protective antiviral immunity. Recent advances in our understanding of the role of DCs during infection with these viruses provide insights into the mechanisms used by these viruses to exploit DC function and evade innate and adaptive immunity. In this Review we highlight the current knowledge about the interaction between DCs and these viruses and the underlying mechanisms that might influence the outcome of viral infections