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ABSTRACT Herbivorous insects tolerate chemical and metabolic variation in their host plant diet by modulating physiological traits. Insect immune response is one such trait that plays a crucial role in maintaining fitness but can be heavily influenced by variation in host plant quality. An important question is how the use of different host plants affects the ability of herbivorous insects to resist viral pathogens. Furthermore, the transcriptional changes associated with this interaction of diet and viral pathogens remain understudied. The Melissa blue butterfly (Lycaeides melissa) has colonised the exotic legumeMedicago sativaas a larval host within the past 200 years. We used this system to study the interplay between the effects of host plant variation and viral infection on physiological responses and global gene expression. We measured immune strength in response to infection by the Junonia coenia densovirus (JcDV) in two ways: (1) direct measurement of phenoloxidase activity and melanisation, and (2) transcriptional sequencing of individuals exposed to different viral and host plant treatments. Our results demonstrate that viral infection caused total phenoloxidase (total PO) to increase and viral infection and host plant interactively affected total PO such that for infected larvae, total PO was significantly higher for larvae consuming the native host plant. Additionally,L. melissalarvae differentially expressed several hundred genes in response to host plant treatment, but with minimal changes in gene expression in response to viral infection. Not only immune genes, but several detoxification, transporter, and oxidase genes were differentially expressed in response to host plant treatments. These results demonstrate that in herbivorous insects, consumption of a novel host plant can alter both physiological and transcriptional responses relevant to viral infection, emphasising the importance of considering immune and detoxification mechanisms into models of evolution of host range in herbivorous insects.
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This content will become publicly available on August 1, 2026
Molecular Mechanisms Underlying Response to Influenza in Grey Seals ( Halichoerus grypus ), a Potential Wild Reservoir
ABSTRACT RNA viruses are infamous for their ability to cross species barriers, posing threats to global health and security. Influenza A virus (IAV) is naturally found in avian hosts but periodically spills over into marine wildlife. IAV outbreaks occur in the Northwest Atlantic, but grey seals (Halichoerus grypus) appear to be less susceptible to IAV compared to other species. The subclinical nature of IAV infection in addition to life history factors suggest grey seals are a potential wild reservoir host for IAV. We investigated differential gene expression among grey seals naturally exposed to IAV to elucidate genetic mechanisms involved in grey seal disease resistance. RNA sequencing was conducted on blood samples (N = 31) collected from grey seal pups in Massachusetts, US between 2014 and 2019. Samples were grouped for analysis based on presence/absence of viral RNA and antibodies. In the presence of IAV RNA, we observed widespread down‐regulation of genes, including immune genes, potentially as a result of IAV‐induced host shutoff. Immune down‐regulation occurred in acute stage of IAV infection (+ viral RNA, − antibodies), followed by up‐regulation of protein production in peak stage (+ viral RNA, + antibodies), possibly as a result of increased viral replication. Evidence of an activated immune response was observed in late stage of infection (− viral RNA, + antibodies) with up‐regulated adaptive immunity genes. We hypothesize that the combination of down‐ and up‐regulated immune gene expression may prevent overstimulation of the immune response, acting as an adaptation in grey seals to resist IAV‐associated mortality.
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- Award ID(s):
- 1922560
- PAR ID:
- 10654457
- Publisher / Repository:
- Wiley
- Date Published:
- Journal Name:
- Molecular Ecology
- Volume:
- 34
- Issue:
- 15
- ISSN:
- 0962-1083
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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