Abstract. The strongly anthropophilic behaviour of Anopheles gambiae Giles sensu stricto (Diptera: Culicidae), the most important malaria vector in Africa, has been demonstrated by field and laboratory studies. Other members of the An. gambiae complex express varied degrees of anthropophily. Anopheles quadriannulatus (Theobald) species A and B are more zoophilic members of the complex and hence are considered to be of no medical importance. Olfactometer experiments with An. quadriannulatus species A have demonstrated attraction to both human and cow odour. To extend these olfactometer observations a choice experiment was conducted in an outdoor cage with a human and a calf as baits, using laboratory‐reared mosquitoes. Anopheles gambiae s.s. (from Liberia) and two strains of An. quadriannulatus species A (SKUQUA from South Africa, SANGQUA from Zimbabwe), marked with different coloured fluorescent powders for identification purposes, were released simultaneously and given an equal opportunity to feed on either host. The experiment was repeated six times. Bloodmeals were identified using the precipitin technique. Anopheles gambiae s.s. showed highly anthropophagic behaviour, taking 88% of bloodmeals from the human host. In contrast, both strains of An. quadriannulatus fed with equal frequency on the human or the calf; the response to either host was not significantly different. These results confirm the olfactometer findings and demonstrate anthropophagic behaviour not previously recorded in this species. This finding has implications for prospective manipulation of host preference for genetic control purposes.
Abstract Background This study investigated the adaptation mechanisms of Pigeons, Toads and Lizards during the rainy season in tropical savanna climates. Male Agama Lizards ( Agama agama ), Afep Pigeons ( Columba unicincta ) and Toads ( Sclerophrys perreti ) were captured at a location in Ibadan, Oyo state. Five (5) Lizards marked: L1 to L5, Afep Pigeons marked: B1 to B5 and Toads marked: T1 to T5. Each of the animals was manually constrained within six to eight hours of capture, and a 1.0-ml syringe was used to obtain blood from the heart or coccygeal vein. Blood samples were collected in an EDTA and plain bottle, respectively. Plasma and sera samples were separated by centrifugation at − 4 °C using a cold centrifuge and then analysed for creatinine, urea, glucose, Mg + , k + , Cl − , Na + , albumin, TP, ALP, ALT, AST, GGT, MDA, SOD, CAT, GSH and haematological parameters. Cervical dislocation was performed on the animals before organs such as kidneys and liver were collected from each of the animals. Each organ collected from each animal was placed in separate plain tubes (filled with phosphate buffer). Result The Pigeon had higher body temperature, urea, glucose, ALP, PCV, haemoglobin concentration, neutrophil and triglyceride compared to the Lizard and Toad, while the Toad had higher Na + , Mg + and Cl − , basophil and monocytes compared to Pigeon and Lizard and the Lizard has higher creatinine, lymphocyte and cholesterol compared to the Pigeon and Toad. On the liver oxidative stress markers, the Pigeon has higher superoxide dismutase and reduced glutathione compared to the Lizard and Toad, while the Toad has higher MDA and catalase compared to the Pigeon and Lizard. On the kidney oxidative stress markers, the Pigeon has higher MDA compared to the Lizard and Toad, while the Toad has higher catalase than the Pigeon and Lizard. Conclusions From this study, the elevated level of lymphocytes in Lizard and eosinophil, basophil and monocytes in Toad suggests that Lizards and Toad are more vulnerable to inflammation. The high value of cholesterol in Lizard and triglyceride in Pigeon as observed in this study may relate to the degree of stress. Also, the activation of antioxidant systems under comparative study is a part of the survival strategy of animals like amphibians, reptiles and aves when facing environmental problems.
Abstract The Mokola Virus belongs to the family Rhabdoviridae and is genotype 3 of the Lyssavirus genera. A small number of cases of animal and human encephalomyelitis, mainly scattered over sub-Saharan Africa, have been linked to the Mokola Virus (MOKV). Currently there is no vaccine to protect against MOKV infection in people or animals. It has been proven that rabies vaccination does not confer immunity against MOKV infection, even though MOKV and the rabies virus are related. Using immunoinformatics approaches, this study designed an mRNA vaccine that can protect against all the five glycoproteins of the Mokola virus. NCBI was used to obtain the viral sequences, which were then screened for antigenicity, allergenicity, toxicity, B-cell epitopes, CD8 + T lymphocytes (CTL), and CD4 + T lymphocytes (HTL). These epitopes were used in the construction of the vaccine. Some extra co-translational residues were added to the mRNA vaccine construct. Its molecular weight is 129.19083 kDa, and its estimated pI is 8.58. It interacts rather steadily and with limited deformability with TLR 3, among other human innate immune receptors. Overall, the results show that the produced candidate vaccine is non-allergen, non-toxic, and can elicit T–cell and B–cell immune responses. These findings can further be subjected to in-vivo and in-vitro techniques for validation.
Attempts are being made to backcross into Anopheles gambiae s.s. the gene(s) which cause zoophily in Anopheles quadriannulatus. Such a backcrossed strain might be preferable to a Plasmodium-refractory strain as a basis for genetic control because a refractory strain could select for evasion of refractoriness in the wild Plasmodium population. The species composition of the malaria vector population in several Tanzanian villages was overwhelmingly An. gambiae s.s. in a normal rainy season, but consisted of four species, all proved by ELISA and/or PCR to carry P. falciparum sporozoites, at the time of the heavy rains associated with El Niño. Thus any scheme, for malaria transmission control by replacement of vectors by genetically-manipulated non-vectors, would have to be able to replace more than one species.
This study examined sexual dimorphism of head morphology in the ecologically diverse three‐spined stickleback Gasterosteus aculeatus . Male G. aculeatus had longer heads than female G. aculeatus in all 10 anadromous, stream and lake populations examined, and head length growth rates were significantly higher in males in half of the populations sampled, indicating that differences in head size increased with body size in many populations. Despite consistently larger heads in males, there was significant variation in size‐adjusted head length among populations, suggesting that the relationship between head length and body length was flexible. Inter‐population differences in head length were correlated between sexes, thus population‐level factors influenced head length in both sexes despite the sexual dimorphism present. Head shape variation between lake and anadromous populations was greater than that between sexes. The common divergence in head shape between sexes across populations was about twice as important as the sexual dimorphism unique to each population. Finally, much of the sexual dimorphism in head length was due to divergence in the anterior region of the head, where the primary trophic structures were found. It is unclear whether the sexual dimorphism was due to natural selection for niche divergence between sexes or sexual selection. This study improves knowledge of the magnitude, growth rate divergence, inter‐population variation and location of sexual dimorphism in G. aculeatus head morphology.
The progeny of two Anopheles plumbeus, collected biting a human in London, were fed on Plasmodiumfakiparum gametocytes grown in vitro. 18-21days after the blood feed. six out often of the mosquitoes had visible sporozoites in their salivary glands and these glands showed strong positivity in an ELISA test for P. falciparum circumsporozoite protein. This confirms earlier suggestions that, 1DllikeAn. atroparvus, An. plumbeus can nurture completion of sporogony of tropical P. falciparum. Following a case of P. falciparum malaria in the north of England more than 70 years ago in a person who had not travelled to the tropics (Blacklock, 1921), and two much more recent such cases in Germany (Krnger et al., 2001), it was suggested that An, plumbeus could have been the vector. If so, this tree-hole breeding species (Blacklock & Carter, 1920b)must differ in parasite susceptibility from the marshland breeding An. atroparvus, which is accepted as having been the vector of P. vivax in northern Europe (Hackett, 1937), but not being susceptible to tropical P. falciparum (Shute, 1940; Ramsdale & Coluzzi, 1975;Dashkova & Rasnicyn, 1982).There is evidence that P. vivax can develop as rMarchant et al., 1998). It remains to check whether sporogony of P. fa/ciparum could be completed in these mosquitoes.
Abstract To determine which species and populations of Anopheles transmit malaria in any given situation, immunological assays for malaria sporozoite antigen can replace traditional microscopical examination of freshly dissected Anopheles. We developed a wicking assay for use with mosquitoes that identifies the presence or absence of specific peptide epitopes of circumsporozoite (CS) protein of Plasmodium falciparum and two strains of Plasmodium vivax (variants 210 and 247). The resulting assay (VecTest TM Malaria) is a rapid, one‐step procedure using a ‘dipstick’ test strip capable of detecting and distinguishing between P. falciparum and P. vivax infections in mosquitoes. The objective of the present study was to test the efficacy, sensitivity, stability and field‐user acceptability of this wicking dipstick assay. In collaboration with 16 test centres world‐wide, we evaluated more than 40 000 units of this assay, comparing it to the standard CS ELISA. The ‘VecTest TM Malaria’ was found to show 92% sensitivity and 98.1% specificity, with 97.8% accuracy overall. In accelerated storage tests, the dipsticks remained stable for >15 weeks in dry conditions up to 45°C and in humid conditions up to 37°C. Evidently, this quick and easy dipstick test performs at an acceptable level of reliability and offers practical advantages for field workers needing to make rapid surveys of malaria vectors.
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