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ARS Home » Midwest Area » Ames, Iowa » National Animal Disease Center » Virus and Prion Research » Research » Research Project #437901

Research Project: ARS Streptococcus Equi Ssp. Zooepidemicus Challenge Study

Location: Virus and Prion Research

Project Number: 5030-32000-119-17-I
Project Type: Interagency Reimbursable Agreement

Start Date: Jan 1, 2020
End Date: Dec 30, 2020

Objective:
Determine the potential threat of Steptococcus equi zooepidemicus (SEZ) to the U.S. swine industry.

Approach:
In the initial study ARS will challenge five sows each with three different isolates of S. zooepidemicus, the isolate from the high mortality event in swine in Tennessee, and two others isolated from non-swine species. This will be modeled after Streptococcus suis challenge studies ARS has performed. Fifteen sows will initially challenge oral-nasally with 10e8-10e9 cfu. Three strains will be used based on expected virulence, with five sows exposed to each strain. Challenged animals will be monitored for two weeks maximum to determine if disease will develop. Samples will be taken starting two weeks prior to the challenge and then regularly during the challenge until death or euthanasia. Samples taken will include blood samples for serum and respiratory swabs and tissues for culture. The pigs will be observed for clinical signs such as lameness, lethargy/depression, dyspnea, neurological signs or other indicators of septicemia, polyserositis, arthritis, or meningitis. If these signs develop the pigs will be euthanized and samples collected for culture and pathology. Samples include swabs from serosal surfaces (pericardium, pleura, and peritoneum), joint fluid, cerebrospinal fluid, lung/lung lavage, liver, spleen, kidney, mandibular lymph nodes, tonsil, serum, or any other clearly abnormal tissues for culture and similar tissues for histopath. The second study will follow a similar design except finisher or market swine will be used.