VACCINATION OF CATTLE IN LATE-TERM PREGNANCY FOR EPIZOOTIC BOVINE ABORTION: IS IT SAFE AND WILL IT CONFER LONG-TERM IMMUNITY TO THE RESULTING OFFSPRING?

• Sponsoring Institution: Cooperating Schools of Veterinary Medicine
• Project Status: COMPLETE
• Funding Source: STATE
• Reporting Frequency: Annual
• Accession No.: 1026456
• Project Start Date: Apr 16, 2021
• Project End Date: Apr 15, 2022
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIVERSITY OF CALIFORNIA, DAVIS
410 MRAK HALL
DAVIS,CA 95616-8671

Performing Department
Pathology, Microbiology & Immunology

Non Technical Summary
Parjaroellobacter abortibovis (P.a.) is the causative agent of epizootic bovine abortion (EBA or foothill abortion), a devastating and costly disease that results in late term abortions or weak calves in pregnant naïve cattle pastured in dry foothill and mountainous areas of CA, NV, OR and AZ. A live, infectious P. a. vaccine has been successfully developed and commercialized. A 60-day window is required between P. a. vaccination and initiation of breeding to prevent early fetal loss; this has created hardship for many producers who wish to vaccinate aged cows but calve too late to provide the minimum vaccination-to-breeding window. Preliminary unpublished studies have demonstrated that fetuses are still susceptible to foothill abortion if exposed as late as 5 months gestation. The current project is designed to determine if pregnant naive cattle can be safely vaccinated in the 3rd trimester without damage to the developing fetus. It also exams if such in utero-exposed calves develop and retain long-term immunity. Both naïve and EBA-immune heifers will be synchronized and bred with sexed (female) semen. Heifers will be vaccinated with the live-virulent foothill vaccine at 6-7 months of gestation and followed through parturition. Their calves will be followed through the 1st 6 months of life to determine if any exhibit signs of foothill abortion or poor health. Body weights will be measured to determine thrift. Serum antibody titers for P.a. will be followed for evidence of passive vs. active immunity. Female offspring will be raised to maturity, synchronized and bred, and then infected with P.a. at 100 days gestation (peak period of susceptibility to EBA) to determine if they developed long-term immunity in utero.

Animal Health Component

50%

Research Effort Categories

Basic

50%

Applied

50%

Developmental

(N/A)

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
315	3310	1090	100%

Knowledge Area
315 - Animal Welfare/Well-Being and Protection;

Subject Of Investigation
3310 - Beef cattle, live animal;

Field Of Science
1090 - Immunology;

Keywords

foothill abortion

epizootic bovine abortion

immunity

safety

in utero immunity

Goals / Objectives
Vaccinate naïve pregnant heifers at approximately 6-7 months gestation with the Pajaroellobacter abortibovis vaccine and determine any impact on fetal health, birth weights and calf weight gains.Establish the presence and persistence of P.a.-specific antibodies in all resulting calves.Breed female offspring (principals and controls) and challenge pregnant animals at approximately 100 days gestation with P. a. to confirm immunity in those receiving in utero P.a. exposure.

Project Methods
Seventy five replacement and first-calf heifers will be synchronized and bred by AI; female sexed semen will be used with replacement heifers to maximize the number of female calves. All will be rested for 2 weeks and bred by natural service for 1 cycle. Ultrasound examinations will be used to determine pregnancy and fetal sex. Bred heifers will be treated with either Pajaroellobacter abortibovis vaccine or placebo at 6-7 months gestation. The same P.a. preparation will be administered to SCID mice to confirm infectivity. All heifers will be tested for exposure to P. a. using serology prior to and following challenge. Abortions or dying neonates will be subjected to diagnostics. Apparently healthy offspring will be followed for thrift (i.e. wt gain) as well as for the presence and persistence of P.a. antibodies. All will be bled three times at two-month intervals between branding and weaning for serology. Female offspring will be bred and challenged with live P. a. to demonstrate presence or absence of in utero-derived immunity.

Progress 04/16/21 to 04/15/22

Outputs
Target Audience:Scientific community, vaccine production companies, animal health experts including veterinarians, university and veterinary extension specialists, beef producers. Changes/Problems:None What opportunities for training and professional development has the project provided?Veterinary students and residents received training in ultrasound based sexing of pregnany cattle and proper diagnosis of EBA How have the results been disseminated to communities of interest?Delivered to producers through the Annual CA Cattlemen's Assocation Meeting and University and Veterinary Extension outreach to producers. Delivered to veterianary students and practioners via formal continuing education programs. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Established that vaccination of naive praegnant heifers greater that 6.5 months of gestation appears to be safe. Pregnant nieve animals less that 6.5 months of gestation can either abort the fetus or give birth to a weak calf. Principal and control female calve's antibody titers were analyzed at approximately 2 month intervals between branding and weaning and again at pre-breeding vaccinations and throughout pregnancy. Data provided compelling evidence that most in utero-exposed calves produced their own antibody, a consistent marker of immunity. Heifer calves were raised to breeding age and were bred and tested for long-term in utero-derived immunity by challenge with the etiologic agent of epizootic bovine abortion (EBA) at 120 days gestation. Eight of ten principals produced healthy calves, one died of dystocia and one aborted due to EBA. All 10 control heifers aborated fetuses which were diagnosed as being due to EBA.

Publications

• Type: Journal Articles Status: Published Year Published: 2022 Citation: Blanchard MT, Teglas MB, Anderson ML, Moore PF, McNabb BR, Collins KM, Yeargan BV, Stott JL. Protection of cattle against Epizootic Bovine Abortion (EBA) using a live Pajaroellobacter abortibovis vaccine. Vaccines (Basel). 2022 Feb 19;10(2):335. doi: 10.3390/vaccines10020335. PMID: 35214793; PMCID: PMC8874702.