Search Results

You are looking at 1 - 2 of 2 items for

  • Author or Editor: Douglas D. Pedersen x
  • Refine by Access: All Content x
Clear All Modify Search

Abstract

Objective—To determine humoral responses to an equine encephalitis vaccine in healthy alpacas.

Design—Clinical trial.

Animals—39 healthy alpacas on 1 farm and 86 healthy alpacas on a second farm.

Procedures—All alpacas were given 3 doses IM of a bivalent, killed-virus equine encephalitis vaccine, with 4 weeks between doses. Eastern equine encephalitis (EEE) virus neutralizing antibody responses were determined with a plaque reduction neutralization assay every 14 days in alpacas on the first farm and 70 days after the first dose of vaccine on the second farm.

Results—For alpacas on the first farm, geometric mean virus neutralizing antibody titer peaked 2 weeks after the third vaccine dose was given (ie, day 70). At this time, 29 of 38 (76%) animals were seropositive for antibodies against EEE virus, and percentage of animals ≤ 2 years old that were seropositive (16/17) was significantly higher than percentage of animals > 6 years old that were seropositive (1/5). For alpacas on the second farm, 76 (88%) were seropositive on day 70, and percentage of animals ≤ 2 years old that were seropositive (24/24) was significantly higher than percentage of animals > 6 years old that were seropositive (27/33). For both farms, geometric mean titer on day 70 was significantly higher in animals < 2 years old than in animals > 6 years old.

Conclusions and Clinical Relevance—Results suggested that inoculation of alpacas with 3 doses of a bivalent, killed-virus equine encephalitis vaccine induced a humoral antibody response against EEE virus.

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To compare neutralizing antibody response between horses vaccinated against West Nile virus (WNV) and horses that survived naturally occurring infection.

Design—Cross-sectional observational study.

Animals—187 horses vaccinated with a killed WNV vaccine and 37 horses with confirmed clinical WNV infection.

Procedure—Serum was collected from vaccinated horses prior to and 4 to 6 weeks after completion of an initial vaccination series (2 doses) and 5 to 7 months later. Serum was collected from affected horses 4 to 6 weeks after laboratory diagnosis of infection and 5 to 7 months after the first sample was obtained. The IgM capture ELISA, plaque reduction neutralization test (PRNT), and microtiter virus neutralization test were used.

Results—All affected horses had PRNT titers ≥ 1:100 at 4 to 6 weeks after onset of disease, and 90% (18/20) maintained this titer for 5 to 7 months. After the second vaccination, 67% of vaccinated horses had PRNT titers ≥ 1:100 and 14% had titers < 1:10. Five to 7 months later, 33% (28/84) of vaccinated horses had PRNT titers ≥ 1:100, whereas 29% (24/84) had titers < 1:10. Vaccinated and clinically affected horses' end point titers had decreased by 5 to 7 months after vaccination.

Conclusions and Clinical Relevance—A portion of horses vaccinated against WNV may respond poorly. Vaccination every 6 months may be indicated in certain horses and in areas of high vector activity. Other preventative methods such as mosquito control are warranted to prevent WNV infection in horses. (J Am Vet Med Assoc 2005;226:240–245)

Restricted access
in Journal of the American Veterinary Medical Association