Dear MARMAM, On behalf of my co-authors, I am excited to share two recently published papers on grey seal response to influenza A virus: McCosker CM, Unal E, Gigliotti A, Puryear WB, Runstadler JA, Murray KT, King BL, Cammen KM. (2025). Molecular mechanisms underlying response to influenza in grey seals (*Halichoerus grypus*), a potential wild reservoir. Molecular Ecology. e70012. Article Link: Molecular Ecology <https://onlinelibrary.wiley.com/doi/10.1111/mec.70012?logout=true> 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. McCosker CM, Levin M, Puryear WB, Runstadler JA, Murray KT, Cammen KM. (2025). Gray Seal (*Halichoerus grypus*) Pups Fail to Mount an Inflammatory Cytokine Response to Influenza A Virus. Journal of Wildlife Disease. 61(3): 628–641. Article link: Journal of Wildlife Diseases <https://meridian.allenpress.com/jwd/article/doi/10.7589/JWD-D-24-00166/507061/Gray-Seal-Halichoerus-grypus-Pups-Fail-to-Mount-an> Abstract: Infectious disease is a naturally occurring phenomenon in healthy ecosystems, but anthropogenic pressures have led to an increase in the spread and intensity of disease outbreaks in recent decades. Ecosystem health and functioning can be monitored through sentinel organisms, such as marine mammals for coastal environments. In the northwest Atlantic Ocean, gray (*Halichoerus grypus*) and harbor (*Phoca **vitulina*) seals are exposed to influenza A virus (IAV) but exhibit apparent differences in disease severity, as gray seals largely remain asymptomatic while harbor seals experience IAV-associated morbidity and mortality. This study aimed to investigate gray seal response to IAV through cytokines, which are signaling proteins responsible for initiating and regulating an immune response. Swabs (nasal, conjunctival, and rectal) and blood samples were collected from wild gray seal pups (n¼116) and used to detect IAV infection and to measure 13 serum cytokines. There was no significant difference in cytokine profiles across IAV infection status, age (as determined by molt stage), or body condition (a proxy of overall health), but individual cytokines were identified as important in differentiating between seals across these categorical variables, and a general trend of lower cytokine detection rates was observed among IAV-infected pups. These results suggest that gray seal pups lack a strong cytokine response during IAV infections. Understanding the immune response of pinnipeds, and mammals more broadly, to viral pathogens is important for predicting how the increased emergence and spread of infectious disease will shape the future of global terrestrial and marine mammal populations. Warm regards, Christina McCosker -- Christina McCosker, PhD School of Marine Sciences, One Health & Environment NRT University of Maine Orono, ME, USA