Role of NF-kβ factor Rel2 during Plasmodium falciparum and bacterial infection in Anopheles dirus.
BACKGROUND
Anopheles mosquitoes transmit malaria which is one of the world's most threatening diseases. Anopheles dirus (sensu stricto) is among the main vectors of malaria in South East Asia. The mosquito innate immune response is the first line of defence against malaria parasites during its development. The immune deficiency (IMD) pathway, a conserved immune signaling pathway, influences anti-Plasmodium falciparum activity in Anopheles gambiae, An. stephensi and An. albimanus. The aim of the study was to determine the role of Rel2, an IMD pathway-controlled NF-kappaβ transcription factor, in An. dirus.


METHODS
RACE (Rapid amplification of cDNA ends) was performed on the Rel2 gene. Double-stranded Rel2 was constructed and injected into the thorax of female mosquitoes. The injected mosquitoes were fed on a P. falciparum gametocyte culture and dissected on day 7-9 post-feeding in order to count the oocysts. A survival analysis was conducted by exposing the dsRNA injected mosquitoes to Gram-positive and Gram-negative bacteria.


RESULTS
This study demonstrated that the Rel2 gene in An. dirus has two isoforms, short length and full length. RNA interference-mediated gene silencing of Rel2 showed that the latter is involved in protection against P. falciparum, Gram-positive bacteria (Micrococcus luteus) with Lys-type peptidoglycan and Gram-negative bacteria (Escherichia coli) with DAP-type peptidoglycan.


CONCLUSIONS
This study suggested that there are similarities in the splicing events and functionality of the Rel2 gene, between the Anopheles species. Among all the important anophelines, the immunity of only a few has been thoroughly investigated. In order to develop novel vector-based control strategies and restrict malaria transmission, the immune pathways of these important vectors should be thoroughly investigated.
Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
Mohammad Behram
MB
Khan
Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
Jonathan Wee Kent
JW
Liew
Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
Cherng Shii
CS
Leong
Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia. lauyeeling@um.edu.my.
Yee-Ling
YL
Lau
Anopheles dirus; Bacterial infection; IMD pathway; Plasmodium falciparum; Rel2
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