Infection Dynamics of Influenza Virus A in California Sea Lions and Northern Elephant Seals
- Infectious disease
Abstract
To understand susceptibility of wild California sea lions and Northern elephant seals to influenza A virus (IAV), we developed an ex vivo respiratory explant model and used it to compare infection kinetics for multiple IAV subtypes. We first established the approach using explants from colonized rhesus macaques, a model for human IAV. Trachea, bronchi, and lungs from 11 California sea lions, 2 Northern elephant seals, and 10 rhesus macaques were inoculated within 24 h postmortem with 6 strains representing 4 IAV subtypes. Explants from the 3 species showed similar IAV infection kinetics, with peak viral titers 48 to 72 h post-inoculation that increased by 2 to 4 log10 PFU/explant relative to the inoculum. Immunohistochemistry localized IAV infection to apical epithelial cells. These results demonstrate that respiratory tissue explants from wild marine mammals support IAV infection. In the absence of the ability to perform experimental infections of marine mammals, this ex vivo culture of respiratory tissues mirrors the in vivo environment and serves as a tool to study IAV susceptibility, host range, and tissue tropism. IMPORTANCE Although influenza A virus can infect marine mammals, a dearth of marine mammal cell lines and ethical and logistical challenges prohibiting experimental infections of living marine mammals mean that little is known about IAV infection kinetics in these species. We circumvented these limitations by adapting a respiratory tract explant model first to establish the approach with rhesus macaques and then for use with explants from wild marine mammals euthanized for nonrespiratory medical conditions. We observed that multiple strains representing 4 IAV subtypes infected trachea, bronchi, and lungs of macaques and marine mammals with variable peak titers and kinetics. This ex vivo model can define infection dynamics for IAV in marine mammals. Further, use of explants from animals euthanized for other reasons reduces use of animals in research.
Liu, H., Plancarte, M., Ball, E.E., Weiss, C.M., Gonzales-Viera, O., Holcomb, K., Ma, Z.M., Allen, A.M., Reader, J.R., Duignan, P.J. and Halaska, B., 2020. Respiratory tract explant infection dynamics of influenza A virus in California sea lions, northern elephant seals, and rhesus macaques. Journal of Virology, pp.JVI-00403.
Pádraig Duignan
Meet The Experts
{"image":"\/People\/Portrait\/cropped-images\/Padraig Duignan-0-56-635-496-1601760621.jpg","alt":"Padraig Duignan","title":"P\u00e1draig Duignan","text":"Director of Pathology","link_url":"https:\/\/www.marinemammalcenter.org\/person\/padraig-duignan","link_text":"Read Bio"}
Related Publications
{"image":"\/Animals\/Wild\/Other species\/nz-sea-lion-shutterstock.jpg","alt":"New Zealand sea lion","title":"Causes of Death in Two Populations of New Zealand Sea Lions","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/causes-of-death-in-two-populations-of-new-zealand-sea-lions","label":"Research Paper"}
{"image":"\/Animals\/Patients\/California sea lions\/csl-by-bill-hunnewell-c-the-marine-mammal-center-6.jpg","alt":"California sea lions","title":"Zoonotic Bacteria Persistence and Susceptibility","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/zoonotic-bacteria-persistence-and-susceptibility","label":"Research Paper"}
{"image":"\/Animals\/Patients\/California sea lions\/cropped-images\/csl-photo-by-bill-hunnewell-c-the-marine-mammal-center-1-0-0-2358-1722-1600891644.jpg","alt":"California sea lions","title":"Emerging Viruses in Marine Mammals","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/emerging-viruses-in-marine-mammals","label":"Research Paper"}
{"image":"\/Animals\/Patients\/California sea lions\/csl-photo-by-bill-hunnewell-c-the-marine-mammal-center-12.jpg","alt":"two California sea lions","title":"Multi-Phase Muscle Breakdown in California Sea Lions","link_url":"https:\/\/www.marinemammalcenter.org\/publications\/multi-phase-muscle-breakdown-in-california-sea-lions","label":"Research Paper"}
Recent News
{"image":"\/Animals\/Patients\/Harbor seals\/cropped-images\/hs-group-with-hats-photo-by-bill-hunnewell-c-the-marine-mammal-center-34-0-1270-992-1750873865.jpg","alt":"Four harbor seals with small ID tags on their heads swim in a rehabilitation pool.","title":"How Our Patients are Named and Identified","link_url":"https:\/\/www.marinemammalcenter.org\/news\/how-our-patients-are-named-and-identified","label":"Patient Update","date":"2025-06-26 02:00:00"}
{"image":"\/Animals\/Wild\/Gray whale\/cropped-images\/gray-whale-oreo-by-josie-slaathaug-c-the-marine-mammal-center-108-0-1270-992-1750880575.jpg","alt":"Gray whale fluke above the water","title":"Los Angeles Times: The numbers of gray whales migrating along the California coast continue to plummet","link_url":"https:\/\/www.marinemammalcenter.org\/news\/los-angeles-times-the-numbers-of-gray-whales-migrating-along-the-california-coast-continue-to-plummet","label":"In the News","date":"2025-06-25 02:00:00"}
Los Angeles Times: The numbers of gray whales migrating along the California coast continue to plummet
June 25, 2025
Read More{"image":"\/Animals\/Wild\/Harbor seal\/cropped-images\/harbor-seal-pup-photo-by-Ruvim-Miksanskiy-251-0-1270-992-1750880392.jpg","alt":"Harbor seal pup resting on the beach","title":"ABC7 San Francisco: Animal trauma could be linked to bad human behavior, Bay Area marine mammal experts say","link_url":"https:\/\/www.marinemammalcenter.org\/news\/abc7-san-francisco-animal-trauma-could-be-linked-to-bad-human-behavior-bay-area-marine-mammal-experts-say","label":"In the News","date":"2025-06-24 02:00:00"}
ABC7 San Francisco: Animal trauma could be linked to bad human behavior, Bay Area marine mammal experts say
June 24, 2025
Read More{"image":"\/People\/Action\/Response\/cropped-images\/mbo-crew-es-rope-rescue-photo-by-lesley-simms-c-the-marine-mammal-center-2-0-0-1270-992-1749571082.jpg","alt":"MBO crew carrying a crate up a cliff","title":"The Marine Mammal Center reports high levels of marine mammal disturbance in Central and Northern California for third year in a row","link_url":"https:\/\/www.marinemammalcenter.org\/news\/the-marine-mammal-center-reports-high-levels-of-marine-mammal-disturbance-in-central-and-northern-california-for-third-year-in-a-row","label":"Press Release","date":"2025-06-10 02:00:00"}
The Marine Mammal Center reports high levels of marine mammal disturbance in Central and Northern California for third year in a row
June 10, 2025
Read More