Interorgan Molecular Communication Strategies of “Local” and “Systemic” Innate Immune Responses in Mosquito Anopheles stephensi

Abstract

Mosquitoes that transmit many deadly infectious diseases also need to keep fighting against many microbial infections. Constitutive expression of multiple antimicrobial peptides (AMPs) in almost all body tissues is believed to facilitate the effective management of these local infections. When any infection breaches the local barrier, AMPs are induced rapidly in non-target tissues such as hemocytes (HCs) and establish their co-ordination with systemic immune effectors to clear off the body infection. But how interorgan immune communication is managed during local and systemic infections remain largely unknown. To understand this interorgan molecular relationship, we identified, extensively profiled and compared the expression of AMPs in three important mosquito tissues viz. midgut, fat body (FB), and HCs. dsRNA-mediated AMPs silencing suggests that mosquito tissues are able to manage an optimal expression of AMPs at the physiological level. We also examined the possible contribution of two important immune regulator genes relish (REL) and nitric oxide synthase, controlling AMPs expression in these tissues during local or systemic infections. We show that each tissue has a unique ability to respond to local/systemic challenges, but HCs are more specialized to recognize and discriminate-specific antigens than gut and FB. Our investigation also revealed that both REL and NO participate in the overall management of the interorgan immune responses, but at the same time each tissue also has its own ability to maintain the interorgan flow of signals. In our knowledge, this is the first large-scale study examining the interorgan immune relationship in the mosquito.

Altered gut microbiota and immunity defines Plasmodium vivax survival in Anopheles stephensi

“…Thus, we hypothesize first 24 hrs of gut-microbe-Plasmodium interaction in the gut lumen are crucial for Plasmodium survival, where it may limit the availability of iron/nutrient required for bacterial growth (Clark, Goheen et al 2014). Corroborating to earlier studies, we also observed that mosquitoes were able to restore basal level of gut flora within 30hrs of uninfected blood meal digestion (Das De et al, 2018). However, surprisingly, P. vivax infection caused a major shift in gut flora restoration to an enriched state after 48 hrs in P. vivax infection.…”

“…A constant 28±2°C temperature and relative humidity of ~80% was maintained in the insectarium. Live rabbit was offered for blood meal for egg maturation and gonotrophic cycle maintenance (Sharma et al 2015;Das De, Sharma et al 2018).…”

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

“…Briefly, post confirmation of P. vivax infection, ~20-25 mosquitoes were dissected at 3-6Days Post Infection (DPI) and 8-10 DPI for midgut, 9-12DPI for hemocytes and 12-14DPI for salivary glands in PBS and collected in trizol reagent. Total RNA was isolated from each dissected tissue sample, and respective double stranded cDNA library was prepared using well established protocol, described earlier (De et al, 2018;Dixit et al, 2011;Sharma et al, 2015). The sequencing of whole transcriptomes was performed on Illumina NextSeq.…”

“…Our initial attempt of mapping of cleaned reads (filtered low quality, microbial and P. vivax origin) to the available draft reference genome was unsuccessful. Alternatively, we mapped all the high quality reads against denovo assembled reference map, as described earlier (De et al, 2018;Sharma et al, 2015;. Though, a read density map analysis revealed P. vivax infection causes a significant suppression in the salivary glands and midgut transcripts, but cause a greater shift in the read density of the infected hemocyte transcripts (Fig.2).…”

“…A standard GO annotation was performed and P. vivax transcripts were analyzed for functional prediction. The gene expression analysis of the selected mosquito and/or P. vivax transcripts was monitored as described earlier (De et al, 2018;; also see…”