New mosquito records of an area known for Japanese encephalitis hyperendemicity, Gorakhpur District, Uttar Pradesh, India

First report of molecular confirmation and phylogenetic analysis of ocular seteriasis in buffalo in India using 12S rRNA

An adult Indian buffalo (Bubalus bubalis) presented with corneal opacity, irritation, and excessive lacrimation from the left eye in the Referral Veterinary Polyclinic-Teaching Veterinary Clinical Complex (RVC-TVCC), Indian Veterinary Research Institute, Izatnagar. Clinical examination revealed a whitish thread-like worm in the left eye's anterior chamber. The worm was surgically removed from the eye with supportive nerve blocks. Light microscopy was used for parasite morphological identification, which provided insight into the worm as female Setaria sp. Genomic DNA was isolated, and polymerase chain reaction amplification of 12S rRNA was conducted for molecular confirmation of the parasite. The amplicon was sequenced and analysed by bioinformatics software. Sequence data showed an amplicon size of 243 bp. Phylogenetic analysis with reference data from the NCBI Genbank database revealed the worm was S. digitata, with a similarity of 99.17%. The common predilection site of S. digitata is in the peritoneal cavity of natural hosts like cattle and buffalo and is mostly non-pathogenic. The aberrant migration of the parasite larva to the brain and eye commonly occurs in goats, sheep, and horses, causing clinical conditions like cerebrospinal nematodiasis (lumbar paralysis) and ocular setariasis, respectively. Nevertheless, until now, there have been no reports of ocular setariasis in buffalo. This report is the first unusual occurrence of ocular setariasis in buffalo and its molecular confirmation and phylogenetic analysis using 12S rRNA.

Functions of Armigeres subalbatus C-type lectins in innate immunity

C-type lectins (CTLs) are a superfamily of calcium-dependent carbohydrate binding proteins containing at least one carbohydrate-recognition domain (CRD) and they are present in almost all metazoans. Insect CTLs may function as pattern-recognition receptors and play important roles in innate immunity. In this study, we selected five AsCTLs from the mosquito Armigeres subalbatus, a natural vector of filarial nematodes, and performed both in vitro and in vivo studies to elucidate their functions in innate immunity. AsCTLMA15, AsCTLGA5 and AsCTL15 were mainly expressed in hemocytes, AsCTL16 was expressed in fat body, while AsCTLMA11 was expressed in both hemocytes and fat body, and only AsCTLMA11 and AsCTL16 were expressed at high levels in adult females. In vitro binding assays showed that all five recombinant AsCTLs could bind to different microbial cell wall components, including lipopolysaccharide (LPS), lipid A, peptidoglycan (PG), lipoteichoic acid (LTA), zymosan and laminarin (beta-1,3-glucan). Recombinant AsCTLs also bound to several Gram-negative and Gram-positive bacteria, and could agglutinate bacterial cells. Injection of double-stranded RNAs (dsRNAs) could significantly reduce expression of the five AsCTL mRNAs, and the survival of mosquitoes treated with dsRNA to AsCTLGA5 was significantly decreased after Escherichia coli infection, but did not change significantly after Micrococcus luteus infection compared to the control groups, suggesting that Ar. subalbatus AsCTLGA5 may participate in innate immunity against E. coli.

Evaluation of larvicidal activity of medicinal plant extracts against three mosquito vectors

OBJECTIVE

To evaluate the mosquito larvicidal activity of plant extracts.

METHODS

The hexane, chloroform, ethyl acetate, acetone, and methanol leaf, flower and seed extracts of Abrus precatorius (A. precatorius), Croton bonplandianum (C. bonplandianum), Cynodon dactylon (C. dactylon), Musa paradisiaca (M. paradisiaca) and Syzygium aromaticum (S. aromaticum) were tested against fourth instar larvae of Anopheles vagus (An. vagus), Armigeres subalbatus (Ar. subalbatus) and Culex vishnui (Cx. vishnui).

RESULTS

The highest larval mortality was found in seed ethyl acetate extracts of A. precatorius and leaf extracts of C. bonplandianum, flower chloroform and methanol extracts of M. paradisiaca, and flower bud hexane extract of S. aromaticum against An. vagus with LC(50) values of 19.31, 39.96, 35.18, 79.90 and 85.90 μg/mL; leaf ethyl acetate and methanol extracts of C. dactylon, flower methanol extract of M. paradisiaca, flower bud methanol extract of S. aromaticum against Ar. subalbatus with LC(50) values of 21.67, 32.62, 48.90 and 78.28 μg/mL, and seed methanol of A. precatorius, flower methanol extract of M. paradisiaca, flower bud hexane extract of S. aromaticum against Cx. vishnui with LC(50) values of 136.84, 103.36 and 149.56 μg/mL, respectively.

CONCLUSIONS

These results suggest that the effective plant crude extracts have the potential to be used as an ideal ecofriendly approach for the control of disease vectors. This study provides the first report on the larvicidal activity of crude solvent extracts of different mosquitoes.

Mosquito records from a hot and dry climatic area experiencing frequent outbreaks of Japanese encephalitis, Bellary district, Karnataka, India

Mosquito species occurring in Bellary district, Karnataka, India were surveyed for Japanese encephalitis (JE) and West Nile virus (WNV) from 2001 to 2003. A total of 37 mosquito species in 6 genera were recovered from larval and adult habitats. Aedes, Anopheles and Culex were represented by 11 species each, Mansonia by 2 species, and Armigeres and Lutzia by a single species. A total of 68,506 mosquitoes belonging to 20 species were collected at dusk. Most (74.6%) were Cx. tritaeniorhynchus and occurred in 2 peaks of abundance in February (304 per man hour density [PMHD]) and October (465 PMHD). The mosquito fauna of Bellary district is not diverse, possibly because of the hot and dry climatic conditions in the area.

Construction and characterization of an expressed sequenced tag library for the mosquito vector Armigeres subalbatus

Background

The mosquito, Armigeres subalbatus, mounts a distinctively robust innate immune response when infected with the nematode Brugia malayi, a causative agent of lymphatic filariasis. In order to mine the transcriptome for new insight into the cascade of events that takes place in response to infection in this mosquito, 6 cDNA libraries were generated from tissues of adult female mosquitoes subjected to immune-response activation treatments that lead to well-characterized responses, and from aging, naïve mosquitoes. Expressed sequence tags (ESTs) from each library were produced, annotated, and subjected to comparative analyses.

Results

Six libraries were constructed and used to generate 44,940 expressed sequence tags, of which 38,079 passed quality filters to be included in the annotation project and subsequent analyses. All of these sequences were collapsed into clusters resulting in 8,020 unique sequence clusters or singletons. EST clusters were annotated and curated manually within ASAP (A Systematic Annotation Package for Community Analysis of Genomes) web portal according to BLAST results from comparisons to Genbank, and the Anopheles gambiae and Drosophila melanogaster genome projects.

Conclusion

The resulting dataset is the first of its kind for this mosquito vector and provides a basis for future studies of mosquito vectors regarding the cascade of events that occurs in response to infection, and thereby providing insight into vector competence and innate immunity.