Use of a modified-live vaccine to prevent persistent testicular infection with bovine viral diarrhea virus.

A commercial vaccine containing modified-live bovine viral diarrhea virus (BVDV; types 1 and 2) was administered to one group of 22 peripubertal bulls 28 days before intranasal inoculation with a type 1 strain of BVDV. A second group of 23 peripubertal bulls did not receive the modified-live BVDV vaccine before intranasal inoculation. Ten of 23 unvaccinated bulls--but none of the vaccinated bulls--developed a persistent testicular infection as determined by immunohistochemistry and polymerase chain reaction.

Fetal protection following exposure to calves persistently infected with bovine viral diarrhea virus type 2 sixteen months after primary vaccination of the dams.

This study demonstrated that the bovine viral diarrhea virus (BVDV; types 1 and 2) fractions of a multivalent vaccine protected pregnant heifers and their fetuses at 149 to 217 days of gestation against exposure to calves persistently infected with BVDV type 2a. Eighty percent (eight of 10) of the control heifers were viremic at least 1 day following challenge, whereas all (20 of 20) BVDV-vaccinated heifers were virus isolation-negative on all postchallenge assessment days. Ninety percent (nine of 10) of the calves born to control heifers but only 5% (one of 20) of calves born to BVDV-vaccinated heifers seroconverted to BVDV type 2 before ingesting colostrum.

Evaluation of the efficacy of a modified-live combination vaccine against bovine viral diarrhea virus types 1 and 2 challenge exposures in a one-year duration-of-immunity fetal protection study.

This study demonstrated that the modified-live bovine viral diarrhea virus (BVDV) type 1 and 2 fractions of a multivalent vaccine protected pregnant heifers and their fetuses against virulent BVDV types 1 and 2 challenge exposures at 370 days after vaccination. All BVDV vaccinated heifers inoculated with either BVDV type 1 or 2 at approximately 62 to 94 days of gestation delivered fetuses or calves that were negative for BVDV by ear-notch immunohistochemistry and virus isolation and serum neutralization on a prenursing serum sample. In comparison, eight of nine and 10 of 10 fetuses or calves from non-BVDV-vaccinated heifers were considered persistently infected following exposure to BVDV type 1 and type 2, respectively.

Evaluation of the efficacy of a modified-live combination vaccine against abortion caused by virulent bovine herpesvirus type 1 in a one-year duration-of-immunity study.

This study demonstrated that a multivalent vaccine containing modified-live bovine herpesvirus type 1 (BHV-1) protected pregnant heifers and their fetuses against virulent BHV-1 challenge exposure at 365 days after vaccination. The percentage of abortions or fetal deaths caused by BHV-1 was significantly higher in control heifers (10 of 10 [100.0%]) than BHV-1-vaccinated heifers (three of 19 [15.

Effects of modified-live bovine viral diarrhea virus vaccines containing either type 1 or types 1 and 2 BVDV on heifers and their offspring after challenge with noncytopathic type 2 BVDV during gestation.

Objective: To compare the efficacy of modified-live virus (MLV) vaccines containing either type 1 bovine viral diarrhea virus (BVDV) or types 1 and 2 BVDV in protecting heifers and their offspring against infection associated with heterologous noncytopathic type 2 BVDV challenge during gestation.

Design: Randomized controlled study.

Animals: 160 heifers and their offspring.

Safety of a modified-live combination vaccine against respiratory and reproductive diseases in pregnant cows.

A combination vaccine (Bovi-Shield FP4 + L5, Pfizer Animal Health) containing modified-live virus (MLV) components against bovine herpesvirus-1 (BHV-1), bovine viral diarrhea virus BVDV), parainfluenza virus-3 (PI3), bovine respiratory syncytial virus (BRSV), and inactivated cultures of Leptospira canicola, grippotyphosa, hardjo, icterohaemorrhagiae, and pomona was evaluated for safety in pregnant beef and dairy animals. Heifers vaccinated prebreeding with the minimum immunizing dose (lowest antigen level initiating immunizing effects) of the vaccine's MLV BHV-1 or BVDV components and during pregnancy (approximately 200 days of gestation) with vaccine containing 10x doses of the same BHV-1 and BVDV components delivered live, healthy calves that were determined to be serologically negative (titer less than 1:2) for neutralizing antibodies to BHV-1 and BVDV prior to nursing. Additionally, in three field safety studies, previously vaccinated cows and heifers that received a field dose (vaccine containing antigen levels required for commercial sale of the MLV combination vaccine during either the first, second, or third trimester of pregnancy had abortion rates similar to those of pregnant cows and heifers vaccinated during the same stage of pregnancy with sterile water diluent.