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Title: Role of bibersteinia trehalosi, respiratory syncytial virus, and parainfluenza-3 virus in bighorn sheep pneumonia

item DASSANAYAKE, ROHANA - Washington State University
item SHANTHALINGAM, SUDARVILI - Washington State University
item SUBRAMANIAM, RENUKA - Washington State University
item BAVANANTHASIVAM, JEGARUBEE - Washington State University
item HALDORSON, GARY - Washington State University
item FOREYT, WILLIAM - Washington State University
item EVERMANN, JAMES - Washington State University
item HERRMANN-HOESING, LYNN - Washington State University
item Knowles Jr, Donald
item SRIKUMARAN, SUBRAMANIAM - Washington State University

Submitted to: Veterinary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/30/2012
Publication Date: 2/22/2013
Citation: Dassanayake, R.P., Shanthalingam, S., Subramaniam, R., Bavananthasivam, J., Haldorson, G.J., Foreyt, W.J., Evermann, J.F., Herrmann-Hoesing, L.M., Knowles Jr, D.P., Srikumaran, S. 2013. Role of bibersteinia trehalosi, respiratory syncytial virus, and parainfluenza-3 virus in bighorn sheep pneumonia. Veterinary Microbiology. 162(1):166-172.

Interpretive Summary: Historically, bighorn sheep (BHS) were abundant throughout western North America, but their numbers declined substantially between mid-19th and 20th centuries due to a variety of factors including loss of habitat, predators, competition with domestic livestock for forage, and diseases. Despite significant efforts to restore populations, respiratory diseases, principally pneumonia caused by bacterial pathogens (and perhaps viruses) remains an important factor limiting the growth of BHS populations. Bacteria that are commonly associated with BHS pneumonia include Mannheimia haemolytica, Bibersteinia trehalosi, Pasteurella multocida and Mycoplasma ovipneumoniae. Antibodies to respiratory syncytial virus (RSV) and parainfluenza-3 virus (PI-3) have been detected in several BHS herds. Furthermore, RSV and PI-3 have been isolated or detected from captive and free ranging BHS. M. haemolytica has been shown to consistently cause fatal pneumonia in BHS under experimental conditions. However, whether B. trehalosi and RSV/PI-3 have the ability to cause fatal pneumonia in BHS has not been extensively studied yet. Administration of leukotoxin-positive B. trehalosi and M. haemolytica resulted in fatal pneumonia in BHS. However RSV/PI-3 and lekuotoxin-negative B. trehalosi were unable to cause fatal pneumonia in BHS in this study. Together with our previous studies in BHS, these new findings should help us develop strategies to control pneumonia out breaks in wild BHS

Technical Abstract: Pneumonic bighorn sheep (BHS) have been found to be culture- and/or sero-positive for Bibersteinia trehalosi, respiratory syncytial virus (RSV), and parainfluenza-3 virus (PI-3). The objective of this study was to determine whether these pathogens can cause fatal pneumonia in BHS. In the first study, two groups of four BHS each were intra-tracheally administered with leukotoxin-positive (Group I) or leukotoxin-negative (Group II) B. trehalosi. All four animals in Group I developed severe pneumonia, and two of them died within 3 days. The other two animals showed severe pneumonic lesions on euthanasia and necropsy. Animals in Group II neither died nor showed gross pneumonic lesions on necropsy, suggesting that leukotoxin-positive, but not leukotoxin-negative, B. trehalosi can cause fatal pneumonia in BHS. In the second study, two other groups of four BHS (Groups III and IV) were intra-nasally administered with a mixture of RSV and PI-3. Four days later, RSV/PI-3-inoculated Group IV and another group of four BHS (Group V, positive control) were intra-nasally administered with Mannheimia haemolytica, the pathogen that consistently causes fatal pneumonia in BHS. All four animals in group III developed pneumonia, but did not die during the study period. However all four animals in Group IV, and three animals in Group V developed severe pneumonia and died within two days of M. haemolytica inoculation. The fourth animal in Group V showed severe pneumonic lesions on euthanasia and necropsy. These findings suggest that RSV/PI-3 can cause non-fatal pneumonia, but are not necessary predisposing agents for M. haemolytica-caused pneumonia of BHS.