Induction of multiple immune signaling pathways in Gryllodes sigillatus crickets during overt viral infections

Authors: Duffield, Kristin; FOQUET, BERT - Illinois State University; Stasko, Judith; HUNT, JOHN - Western Sydney University; SADD, BEN - Illinois State University; SAKALUK, SCOTT - Illinois State University; Ramirez, Jose

Submitted to: Viruses
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/30/2022
Publication Date: 12/3/2022
Citation: Duffield, K.R., Foquet, B., Stasko, J.A., Hunt, J., Sadd, B.M., Sakaluk, S.K., Ramirez, J.L. 2022. Induction of multiple immune signaling pathways in Gryllodes sigillatus crickets during overt viral infections. Viruses. 14(12). Article 2712. https://doi.org/10.3390/v14122712.
DOI: https://doi.org/10.3390/v14122712

Interpretive Summary: Despite decades of focus on crickets as a popular commodity and model organism, we still know very little about their immune responses to microbial (e.g., viral) pathogens. Furthermore, the prevalence of covert viral infections (i.e., asymptomatic infections with low viral loads) in insect populations is becoming increasingly apparent, yet we do not fully understand the mechanisms that maintain low viral loads. To better understand how crickets defend against active viral infections, we measured the expression of cricket immune defense genes in populations with covert and active viral infections. Our results indicate that crickets with active viral infections are activating several genes known to be involved in the defense against viral infection in insects. Overall, this study provides the first insight into cricket antiviral defenses at the molecular level and will aid future studies aimed at understanding cricket resistance to infection during mass-reared commercial applications.

Technical Abstract: Despite decades of focus on crickets (family: Gryllidae) as a popular commodity and model organism, we still know very little about their immune responses to microbial pathogens. Previous studies have measured downstream immune effects (e.g., encapsulation response, circulating hemocytes) following an immune challenge in crickets, but almost none have identified and quantified the expression of immune genes during an active pathogenic infection. Furthermore, the prevalence of covert (i.e., asymptomatic) infections within insect populations is becoming increasingly apparent, yet we do not fully understand the mechanisms that maintain low viral loads. In the present study, we measured the expression of several genes across multiple immune pathways in Gryllodes sigillatus crickets with an active or covert infection of cricket iridovirus (CrIV). Crickets with active infections had higher relative expression of key pathway component genes across the Toll, Imd, Jak/STAT, RNAi, and Pvr pathways. These results indicate that crickets can tolerate low viral infections but can mount a robust immune response during an active CrIV infection. Moreover, this study provides insight into the immune strategy of crickets following viral infection and will aid future studies looking to quantify immune investment and improve resistance to pathogens.