Anopheles stephensi (Asian malaria mosquito, SDA-500) Assembly and Gene Annotation

About Anopheles stephensi

Range

Anopheles stephensi is a major malaria vector with a geographical range from the Middle East through the Indian subcontinent and China. Throughout its natural range, Anopheles stephensi is an important vector for both Plasmodium falciparum and Plasmodium vivax. The strain used for this genome sequencing project is the Indian Wild Type strain originally established at the Walter Reed Army Institute of Research. It belongs to the
"type
" biological form and has a segregating 2Rb inversion.

Habitats

Larvae of An. stephensi breed in various artificial containers in homes and collections of water associated with construction sites and other industrial locations. In rural areas, An. stephensi larvae utilise fresh-water pools, stream margins and stream beds, catch basins, seepage canals, wells and domestic water-storage containers. Larvae have also been found in domestic wells, overhead water tanks, room coolers, cisterns and roof gutters in the city of Delhi, but greater numbers of larvae are typically found outdoors compared with indoors. Larvae of the mysorensis form (distinguishable by egg morphology) appear to exclusively inhabit stone pots and earthenware containers. In rural areas of Gujarat, An. stephensi is associated with canal-irrigated, non-irrigated and riverine villages all year round, but generally in low densities. In urban areas, An. stephensi is found throughout the year, but is most abundant in the summer months (between June and August), which coincides with the peak period of malaria transmission.

Resting and feeding preferences

An. stephensi is generally considered to be an endophilic and endophagic species even though it will bite outdoors during the warmer summer months due to greater outdoor activity of humans and domestic animals. This species rests primarily in temporary or poorly constructed human and animal shelters rather than brick structures. Outdoor blood-feeding activity varies seasonally, with females feeding later in the night during the summer months compared to the winter months. However, indoor biting frequencies of An. stephensi appear to show no marked seasonal variation during different months of the year. Blood-meal analyses of An. stephensi females collected in urban areas indicated an increased tendency to feed on humans rather than cattle and other indications of variable anthropophily have been observed, depending on the availability of alternative hosts.

Vectorial capacity

An. stephensi is recognised as an important vector of malaria in urban areas bordering the Persian Gulf, including western and northwestern India. There are three known forms of An. stephensi including the typical form which is an efficient vector of urban malaria, the intermediate form, which is typically found in rural villages and peri-urban areas, but very little is known about its vector status, and the mysorensis form which is restricted to rural areas with poor vectorial capacity due to its highly zoophilic behaviour. The mysorensis form is, however, considered an important vector in Iran.

This text was modified from Sinka ME et al. (2011) The dominant Anopheles vectors of human malaria in Asia-Pacific: occurrence data, distribution maps and bionomic précis Parasites & Vectors 4:89.

SDA-500 strain

Originally isolated from Pakistan, isofemale selection was performed prior to genome sequencing.

For more details about the strain:

Neafsey et al (121 authors). 2015. Highly evolvable malaria vectors: The genomes of 16 Anopheles mosquitoes. Science. Published Online November 27 2014

Source: VectorBase

Picture credit: Jim Gathany, CDC Public domain via Wikimedia Commons (Image source)

AsteS1 assembly

This assembly was generated using 101 bp paired-end Illumina HiSeq2000 reads generated from three libraries: a 180 bp insert 'fragment' library, a 1.5 kb 'jump' library, and a 38 kb 'fosill' library. Sequencing template for the fragment and jump libraries was derived from genomic DNA extracted from a single individual, which was preserved by freezing at -80C. Native genomic DNA was used for the fragment library and whole genome amplified DNA was used for the jump library. Template for the fosill library was generated from a pooled extraction of many individuals. Reads were assembled at the Broad Institute using the ALLPATHS LG algorithm, with the Haploidify option enabled to address high allelic heterozygosity in the template.

AsteS1.8 gene set

Community annotation patch build for July 2019

References

1. Mosquito genomics. Highly evolvable malaria vectors: the genomes of 16 Anopheles mosquitoes.
   Neafsey DE et al (121 authors). 2015. Science. 347(6217)
2. Genome analysis of a major urban malaria vector mosquito, Anopheles stephensi.
   Jiang X, Peery A, Hall AB, Sharma A, Chen XG, Waterhouse RM, Komissarov A, Riehle MM, Shouche Y, Sharakhova MV et al. 2014. Genome Biol.. 15(9)
3. The dominant Anopheles vectors of human malaria in the Asia-Pacific region: occurrence data, distribution maps and bionomic prcis.
   Sinka ME, Bangs MJ, Manguin S, Chareonviriyaphap T, Patil AP, Temperley WH, Gething PW, Elyazar IR, Kabaria CW, Harbach RE et al. 2011. Parasit Vectors. 4

Picture credit: VectorBase.org