DETECTION OF SARS-COV-2 NEUTRALIZING ANTIBODIES IN RETROPHARYNGEAL LYMPH NODE EXUDATES OF WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS) FROM NEBRASKA, USA.

Disease surveillance testing for emerging zoonotic pathogens in wildlife is a key component in understanding the epidemiology of these agents and potential risk to human populations. Recent emergence of SARS-CoV-2 in humans, and subsequent detection of this virus in wildlife, highlights the need for developing new One Health surveillance strategies. We used lymph node exudate, a sample type that is routinely collected in hunter-harvested white-tailed deer (WTD, Odocoileus virginianus) for surveillance of chronic wasting disease, to assess anti-SARS-CoV-2 neutralizing antibodies. A total of 132 pairs of retropharyngeal lymph nodes collected from Nebraska WTD harvested in Nebraska, US, in 2019 (pre-SARS-CoV-2 pandemic) and 2021 (post-SARS-CoV-2 pandemic) were tested for SARS-CoV-2 with reverse transcription PCR. Thereafter, exudates obtained from these same lymph nodes were tested for SARS-CoV-2 neutralizing antibodies using a surrogate virus neutralization test. Neutralizing antibodies were detected in the exudates with high diagnostic specificity (100% at proposed cutoff of 40% inhibition). Application of this testing approach to samples collected for use in other disease surveillance activities may provide additional epidemiological data on SARS-CoV-2 exposure, and there is further potential to apply this sample type to detection of other pathogens of interest.

Bighorn sheep show similar in-host responses to the same pathogen strain in two contrasting environments.

Ecological context-the biotic and abiotic environment, along with its influence on population mixing dynamics and individual susceptibility-is thought to have major bearing on epidemic outcomes. However, direct comparisons of wildlife disease events in contrasting ecological contexts are often confounded by concurrent differences in host genetics, exposure histories, or pathogen strains. Here, we compare disease dynamics of a Mycoplasma ovipneumoniae spillover event that affected bighorn sheep populations in two contrasting ecological contexts. One event occurred on the herd's home range near the Rio Grande Gorge in New Mexico, while the other occurred in a captive facility at Hardware Ranch in Utah. While data collection regimens varied, general patterns of antibody signal strength and symptom emergence were conserved between the two sites. Symptoms appeared in the captive setting an average of 12.9 days postexposure, average time to seroconversion was 24.9 days, and clinical signs peaked at approximately 36 days postinfection. These patterns were consistent with serological testing and subsequent declines in symptom intensity in the free-ranging herd. At the captive site, older animals exhibited more severe declines in body condition and loin thickness, higher symptom burdens, and slower antibody response to the pathogen than younger animals. Younger animals were more likely than older animals to clear infection by the time of sampling at both sites. The patterns presented here suggest that environment may not be a major determinant of epidemiological outcomes in the bighorn sheep-M. ovipneumoniae system, elevating the possibility that host- or pathogen-factors may be responsible for observed variation.