Genetic changes of P. vivax tempers host tissue-specific responses in Anopheles stephensi

Abstract

In our preceding study (Sharma et al., 2019; BioRxiv) we showed that in the gut lumen Plasmodium vivax follows a unique strategy of immuno-suppression by disabling gut flora proliferation. Here, we further demonstrate that post gut invasion, a shrewd molecular relationship with individual tissues such as midgut, hemocyte, salivary glands, and strategic changes in the genetic makeup of P. vivax favors its survival in the mosquito host. A transient suppression of 'metabolic machinery by early oocysts, and increased immunity' against late oocysts suggested a unique mechanism of gut homeostasis restoration and Plasmodium population regulation. Though a hyper immune response of hemocyte was a key to remove free circulating sporozoites, but a strong suppression of salivary metabolic activities, may favor successful survival of invaded sporozoites. Finally, genetic alteration of P. vivax ensures evasion of mosquito responses. Conclusively, our system-wide RNAseq analysis provides first genetic evidences of direct mosquito-Plasmodium interaction and establishes a functional correlation.Author Summary: Malaria transmission dynamics is heavily influenced by mosquito -parasite interaction. When passing through tissue specific barriers, Plasmodium have to compromise by losing its own population, but genetic relation is unknown. To win the developmental race Plasmodium need to overcome two important immuno-physiological barriers. First one accounts an indirect 24-30hr long pre-invasive gut-microbe-parasite interaction in the gut lumen. And second one follows a direct post gut invasive 14-18 days interaction with midgut, hemocyte and salivary glands. During pre-invasive phase of interaction, we showed Plasmodium vivax follows immuno-suppression strategy by restricting microbial growth in the gut lumen. Here, we demonstrate that switch of parasite from one stage to another stage within mosquito vector is accompanied by genetic changes of parasite. Our data suggests genetic makeup change enables the parasite to manipulate the metabolism of mosquito tissues. This strategy not only clear off multifaceted mosquito's tissue specific immune responses, but also favors Plasmodium own survival and transmission. Comprehending this tissue specific interaction between host and parasite at molecular level could provide new tool to intervene the plasmodium life cycle within vector.

Hemocyte‐specific FREP13 abrogates the exogenous bacterial population in the hemolymph and promotes midgut endosymbionts in Anopheles stephensi

“…For multiple sequence alignment, full-length sequences of translated proteins were aligned in ClustalX2 and a phylogenetic tree was prepared by applying neighbor-joining method using MEGA X software. To further select hemocytespecific FREPs, we manually screened in-house preannotated RNA-seq databases originating from na€ ıve, sugar-fed, blood-fed, bacterial-challenged and P. vivax-infected mosquito hemocytes 38,39,40 , and cross-matched the aforesaid genome-predicted catalogs to label accordingly.…”

“…stephensi mosquitoes. While annotating, we enumerated several putative transcripts, which may have a specific function against either bacteria or Plasmodium infection 38,39,40 . Because FREPs are major pattern recognition receptors and immune activators, here, we analyzed the FREPs distinctly expressed in the hemocytes of An.…”

“…stephensi mosquitoes though artificial membrane feeders. 34,40 After confirmation of positive infection, 20 or 25 hemocytes and midgut samples of the mosquitoes were collected.…”

SalivaryAsHPX12influence pre-blood meal associated behavioral properties in the mosquitoAnopheles stephensi

“…Several studies suggest that during blood feeding the salivary cocktail composition is rapidly depleted (24), but how the host-odor activated salivary glands manages 'prior and post' blood-meal associated changing physiologies is largely unknown (26). We aimed to screen and test the possible role of HPX12, whose transcripts enriched in response to P. vivax infection (39) in the regulation of changing physiological homeostasis. Sequence conservation of AsHPX12 with other mosquito species suggested its conserved functions in the blood-feeding behavior of hematophagous insects (41).…”

“…Our recent RNAseq study demonstrates that P. vivax sporozoites significantly modulates the molecular architecture of the mosquitoes' salivary glands (39). To identify the transcripts having a crucial impact on salivary physiology and antioxidant defense responses, we selectively cataloged at least six transcripts encoding heme-peroxidase homologous proteins (Table-1) from transcriptomic data (38).…”