Two Novel Mosquitocidal Peptides Isolated from the Venom of the Bahia Scarlet Tarantula (Lasiodora klugi).

Effective control of diseases transmitted by Aedes aegypti is primarily achieved through vector control by chemical insecticides. However, the emergence of insecticide resistance in A. aegypti undermines current control efforts. Arachnid venoms are rich in toxins with activity against dipteran insects and we therefore employed a panel of 41 spider and 9 scorpion venoms to screen for mosquitocidal toxins. Using an assay-guided fractionation approach, we isolated two peptides from the venom of the tarantula Lasiodora klugi with activity against adult A. aegypti. The isolated peptides were named U-TRTX-Lk1a and U-TRTX-Lk2a and comprised 41 and 49 residues with monoisotopic masses of 4687.02 Da and 5718.88 Da, respectively. U-TRTX-Lk1a exhibited an LD50 of 38.3 pmol/g when injected into A. aegypti and its modeled structure conformed to the inhibitor cystine knot motif. U-TRTX-Lk2a has an LD50 of 45.4 pmol/g against adult A. aegypti and its predicted structure conforms to the disulfide-directed ß-hairpin motif. These spider-venom peptides represent potential leads for the development of novel control agents for A. aegypti.

Single-Nucleotide Polymorphism Associates' ß-Tubulin Isotype-1 Gene in Onchocerca volvulus Populations in Ivermectin-Treated Communities in Taraba State, Nigeria.

PURPOSE: The occurrence of Single-Nucleotide Polymorphisms (SNPs) associated with repeated ivermectin treatment and sub-optimal responses reported by previous findings is of great concern in Onchocerciasis endemic areas. This study investigated SNPs' occurrence after 15 years of ivermectin intervention in Onchocerciasis endemic communities in two Local Government Areas of Taraba State, Nigeria. METHODS: Microfilariae samples were collected by skin snip from individuals treated with ivermectin for 10-15 years of annual distribution and preserved in RNAlater® in a 1.5 ml micro-centrifuge tube. Genomic DNA was extracted from microfilariae and residual skin, amplification in two regions within the ß-tubulin gene, sequenced and analyzed for SNPs using Bioinformatics tools. RESULTS: Three distinct SNP positions: 1183 (T/G), 1188 (T/C) and 1308 (C/T) on the ß-tubulin gene on the targeted 1083-1568 bp fragment, associate's with the ivermectin-treated population. Furthermore, SNPs positions detected in this study are 1730 (A/G) and 1794 (T/G) in the ß-tub gene in the 1557-1857 (bp) region. The 1794 (T/G) SNP position (Phe243Val) in the exon within the ß-tubulin gene region were observed in this study. CONCLUSION: The present study indicates that SNPs are observed in Onchocerca volvulus, thus strengthening the warning that genetic changes could occur in some parasite populations in some ivermectin-treated areas.

Evaluation of Actin-1 Expression in Wild Caught Wuchereria bancrofti-Infected Mosquito Vectors.

BACKGROUND: Wuchereria bancrofti is the major cause of lymphatic filariasis transmitted by mosquito vectors. In the vector-parasite interaction and among other proteins, actin-1 has been implicated for successful transmission of the pathogen in laboratory-controlled experiments. However, validation of this finding from the pathogen's natural environment is required. OBJECTIVE: This study is aimed at evaluating actin-1 expression upon Wuchereria bancrofti infection in mosquito vectors collected during an epidemiology study in Tsafe Local Government Area of Zamfara State, Nigeria. METHODS: Mosquitoes were collected and identified using morphological keys, which include length of maxillary palps, pale spots on the wings, and scale patterns on the abdomen. This was followed by detection of the 188 bp SspI marker of Wuchereria bancrofti infection using polymerase chain reaction (PCR). The mRNA levels of the actin-1 gene were evaluated in the infected Anopheles gambiae sl and Culex quinquefasciatus and their controls, which were adult reared from the larvae in the study area. RESULTS: The mosquitoes were identified to be Anopheles gambiae sl and Culex quinquefasciatus, while infection by Wuchereria bancrofti was confirmed by amplification of the 188 bp SspI marker. A 4.85 and 4.09 relative fold increase in actin-1 gene expression in Wuchereria bancrofti-infected Anopheles gambiae sl and Culex quinquefasciatus was observed. Thus, for the first time we reported that the actin-1 gene in wild caught mosquito vectors (Anopheles gambiae sl and Culex quinquefasciatus) infected with Wuchereria bancrofti is upregulated. CONCLUSION: The actin-1 gene is upregulated and similarly expressed during W. bancrofti infection in mosquito vectors in the study area and this may likely serve as a biomarker and viable strategy for the control of parasite transmission in endemic areas.

Kolaviron shows anti-proliferative effect and down regulation of vascular endothelial growth factor-C and toll like receptor-2 in Wuchereria bancrofti infected blood lymphocytes.

The anti-proliferative effect and down regulation of vascular endothelial growth factor C and toll like receptor-2 by kolaviron on Wuchereria bancrofti infected peripheral blood lymphocytes were investigated. Blood were collected from consenting volunteers in Talata Mafara, Nigeria, between the hours of 10pm to 12am, and microscopically identified for microfilariae. W. bancrofti positive samples were cultured for 72h treated with Doxycycline (2µg/ml) and kolaviron (5µg/ml) in vitro. Mitotic index, expression of vascular endothelial growth factor-C (VEGF-c), toll like receptor-2 (TLR-2) were determined using standard procedures. Mitotic index was significantly (P<0.05) reduced in the kolaviron treated group compared to negative control. Kolaviron also significantly (P<0.05) down regulated the expression of VEGF-c and TLR-2 when compared with the untreated group. In both cases, the effects of kolaviron was not significantly different (P<0.05) to that of doxycycline. Furthermore, strong positive correlations between mitotic index, VEGF-c and TLR-2 expressions were observed. The study suggests that kolaviron rich portion of Garcinia kola exhibited anti-proliferative effect and down regulation of VEGF-c and TLR-2 in W. bancrofti infected blood. Thus, the results from this study might have unravelled the potency of kolaviron in the management of complications associated with lymphatic filariasis.

Distribution of pfmdr1 and pfcrt chloroquine drug resistance alleles in north-western Nigeria.

BACKGROUND: In Nigeria, decline in the sensitivity of Plasmodium falciparum to Artemisinin Combination Therapy (ACT) has prompted the unofficial use of chloroquine (CQ) for self-medication. This study was designed to determine the prevalence and distribution of CQ resistant/susceptible alleles of CQ resistance transporter (Pfcrt) and P. falciparum multidrug resistance gene 1 (Pfmdr1) in view of the possible re-introduction of CQ for malaria treatment. MATERIALS AND METHODS: Four hundred and sixty six (466) P. falciparum positive samples were randomly collected from five states of northwest Nigeria. The samples were amplified using RT- PCR at codon 76 for Pfcrt and codon 86 for Pfmdr1. Data was analysed using chi-square, odds ratios and paired t-tests. RESULTS: Drug susceptible alleles (N86) were most prevalent in the study population (47.9%; 223/466), followed by the drug resistance alleles 86Y (28.3%; 132/466), followed by the drug susceptible alleles K76 (17.4%; 81/466), the resistant alleles 76T (12.4%; 58/466) and finally the mixed infection mutation K76T (3.6%; 17/466). Differences between the distributions of the Pfmdr1 and Pfcrt alleles were significant (P<0.05). There were significant differences (P<0.05) between N86 and 86Y alleles, but no significant differences between K76 and 76T alleles, including the prevalence of the various alleles across the different age groups. CONCLUSION: The results of this study suggest the possibility of (re)introducing CQ for malaria treatment in north-western Nigeria and provide insight in the genetic background of P. falciparum in the study area.

Building sustainable neuroscience capacity in Africa: the role of non-profit organisations.

While advances in neuroscience are helping to improve many aspects of human life, inequalities exist in this field between Africa and more scientifically-advanced continents. Many African countries lack the infrastructure and appropriately-trained scientists for neuroscience education and research. Addressing these challenges would require the development of innovative approaches to help improve scientific competence for neuroscience across the continent. In recent years, science-based non-profit organisations (NPOs) have been supporting the African neuroscience community to build state-of-the-art scientific capacity for sustainable education and research. Some of these contributions have included: the establishment of training courses and workshops to introduce African scientists to powerful-yet-cost-effective experimental model systems; research infrastructural support and assistance to establish research institutes. Other contributions have come in the form of the promotion of scientific networking, public engagement and advocacy for improved neuroscience funding. Here, we discuss the contributions of NPOs to the development of neuroscience in Africa.