Vijay S, Rawat M, Adak T, Dixit R, Nanda N, Srivastava H, Sharma JK, Prasad GBKS, Sharma A. Parasite killing in malaria non-vector mosquito Anopheles culicifacies species B: implication of nitric oxide synthase upregulation.
PLoS One 2011;
6:e18400. [PMID:
21483693 PMCID:
PMC3070730 DOI:
10.1371/journal.pone.0018400]
[Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Accepted: 03/07/2011] [Indexed: 02/05/2023] Open
Abstract
Background
Anopheles culicifacies, the main vector of human malaria in
rural India, is a complex of five sibling species. Despite being
phylogenetically related, a naturally selected subgroup species B of this
sibling species complex is found to be a poor vector of malaria. We have
attempted to understand the differences between vector and non-vector
Anopheles culicifacies mosquitoes in terms of
transcriptionally activated nitric oxide synthase (AcNOS)
physiologies to elucidate the mechanism of refractoriness. Identification of
the differences between genes and gene products that may impart refractory
phenotype can facilitate development of novel malaria transmission blocking
strategies.
Methodology/Principal Findings
We conducted a study on phylogenetically related susceptible (species A) and
refractory (species B) sibling species of An. culicifacies
mosquitoes to characterize biochemical and molecular differences in
AcNOS gene and gene elements and their ability to
inhibit oocyst growth. We demonstrate that in species B, AcNOS specific
activity and nitrite/nitrates in mid-guts and haemolymph were higher as
compared to species A after invasion of the mid-gut by P.
vivax at the beginning and during the course of blood feeding.
Semiquantitative RT-PCR and real time PCR data of AcNOS
concluded that this gene is more abundantly expressed in midgut of species B
than in species A and is transcriptionally upregulated post blood meals.
Dietary feeding of L-NAME along with blood meals significantly inhibited
midgut AcNOS activity leading to an increase in oocyst production in
An. culicifacies species B.
Conclusions/Significance
We hypothesize that upregulation of mosquito innate cytotoxicity due to NOS
in refractory strain to Plasmodium vivax infection may
contribute to natural refractoriness in An. culicifacies
mosquito population. This innate capacity of refractory mosquitoes could
represent the ancestral function of the mosquito immune system against the
parasite and could be utilized to understand the molecular basis of
refractoriness in planning effective vector control strategies.
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