The origin of Plasmodium falciparum in South America is controversial. Some studies suggest a recent introduction during the European colonizations and the transatlantic slave trade. Other evidence—archeological and genetic—suggests a much older origin. We collected and analyzed P. falciparum isolates from different regions of the world, encompassing the distribution range of the parasite, including populations from sub-Saharan Africa, the Middle East, Southeast Asia, and South America. Analyses of microsatellite and SNP polymorphisms show that the populations of P. falciparum in South America are subdivided in two main genetic clusters (northern and southern). Phylogenetic analyses, as well as Approximate Bayesian Computation methods suggest independent introductions of the two clusters from African sources. Our estimates of divergence time between the South American populations and their likely sources favor a likely introduction from Africa during the transatlantic slave trade.
Observational studies on the humoural immune responses of the Warao indigenous people from Delta Amacuro, an isolated area, were compared with urban residents of the Venezuelan capital. Mycobacterium tuberculosisspecific reactivities (IgM, IgE, sIgA, IgG and IgG subclasses) Key words: tuberculosis -Warao -Creole -IgG subclasses -purified protein derivative -diagnosis Tuberculosis (TB) diagnosis needs to be improved, as it largely depends upon clinical examination and radiographic findings, mainly confirmed by sputum smear microscopy and bacterial culture (Murray et al. 1980). The latter requires a long cultivation period and diagnostic confirmation still relies on sputum smear examinations. Many alternative methodologies have been applied in TB diagnosis, such as western blot, microscopic observed direct sensitivity culture, PCR and cell-mediated immune response reactions (Moore et al. 2006, Negi et al. 2006. These methods require trained personnel and specific laboratory conditions, which hinder their implementation in many areas of high TB endemicity (mainly low-income countries) and field work application. On the other hand, there are other options that are currently under evaluation, including antibody detection by serology. While specific antibody detection by serology is under evaluation for a definitive demonstration that the humoural response can be used as a tool for the diagnosis of TB, future studies should be carried out in order to combine serological and cellular methods, such as T.SPOT-TB or Quantiferon Gold assay, which are considered to be approved tools. Regarding the immunodiagnosis of TB based on the T cell response to ESAT-6 and purified protein derivative (PPD) antigens, recently it has been reported that the IFN-γ assay using ESAT-6 as an antigenic stimulus has the potential to be used as a tool for the immunodiagnosis of early TB in children ( Van-Lume et al. 2008).The demand for a rapid, reliable, cost-effective and easy TB diagnostic tool focuses on antibody detection by serology (Bothamley 1995). It has been reported that the isotypic restriction of antibodies correlates with the biochemical nature of antigens; most antibodies against proteins are of IgG1 and IgG3 isotypes, while in those against carbohydrates IgG2 is over-represented (Chiang et al. 1997, Gupta et al. 2005. This is reflected in vivo where, for instance, antibody responses to viral proteins are mainly of the IgG1 and IgG3 subclasses. In contrast, bacteria carbohydrates usually induce type 2 T-independent responses, mainly of the IgG1 and IgG2 isotypes. Several ELISA tests have been attempted and results have presented a large variability in their accuracy depending on the antigen employed (one alone or a pool) (Chiang et al. 1997, Gupta et al. 2005, the immunoglobulin (Ig) class, the subclass measured (Radin et al. 1983, Daniel & Debane 1987, Pottumarthy et al. 2000, Conde et al. 2004, Imaz et al. 2004 and Mycobacterium tuberculosis strain variation (Alde et al. 1989, Zheng et al. 1994, Raja et al. 2002. This indicate...
A monoclonal antibody (MoAb) 2C6111 specific for Plasmodium vivax erythrocytic stages was shown to detect parasitized erythrocytes in blood samples collected in the field. This MoAb binds to the mature trophozoite, schizont and gametes of P. vivax and upon examination of 43 wild isolates no evidence of polymorphism was found. To search for P. vivax parasites in human blood a MoAb immunofluorescent test (MoAb-IFT) was developed. The assay is based on the ability of fluorescein isothiocyanate labelled MoAb 2C6111 to combine with parasitized erythrocytes on thin blood smears. A preliminary field trial was carried out in Venezuela to determine the usefulness of MoAb-IFT for the specific diagnosis of P. vivax malaria. Blood samples collected from malarious and non-malarious individuals were examined both by standard microscopy of Giemsa stained thick blood smears (G-TS) and MoAb-IFT. The latter was specific and gave a 100% correlation with G-TS. Sensitivity was close to that usually achieved with Giemsa stained blood films.
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