Objective—To inoculate white-tailed deer (Odocoileus virginianus) during the sixth or seventh week of gestation with bovine viral diarrhea virus (BVDV) and observe for signs of reproductive tract disease during a 182-day period.
Animals—10 pregnant white-tailed deer (8 seronegative and 2 seropositive [control deer] for BVDV).
Procedures—Deer were inoculated with 1 of 2 deer-derived BVDV strains (RO3-20663 or RO3-24272). Serum anti-BVDV antibody titers were determined prior to and 21 or 35 days after inoculation. Virus isolation (VI) procedures were performed on tissues from fetuses and does that died and on blood samples collected from live fawns. Ear notch specimens obtained from live fawns were assessed by use of BVDV antigen-capture ELISA (ACE).
Results—Both RO3-20663–inoculated seropositive deer gave birth to apparently normal fawns. Among the RO3-24272–inoculated seronegative deer, 1 died, and 1 aborted and 1 resorbed their fetuses; among the RO3-20663–inoculated seronegative deer, 3 died, 1 aborted its fetus, and 1 gave birth to 2 fawns that were likely persistently infected. On the basis of VI and ACE results, those 2 fawns were positive for BVDV; both had no detectable neutralizing anti-BVDV antibodies in serum.
Conclusions and Clinical Relevance—Reproductive tract disease that developed in pregnant white-tailed deer following BVDV inoculation was similar to that which develops in BVDV-exposed cattle. Methods developed for BVDV detection in cattle (VI, immunohistochemical evaluations, and ACE) can be applied in assessments of white-tailed deer. Fawns from does that had serum anti-BVDV antibodies prior to inoculation were protected against BVDV infection in utero.
Objective—To evaluate persistence of bovine viral
diarrhea virus (BVDV) in semen after inoculation of
Animals—Three 2-year-old bulls and five 6-month-old
Procedure—3 seronegative 2-year-old bulls were
inoculated intranasally with BVDV. Serum and semen
samples were obtained at regular intervals until 7
months after inoculation. Serum samples were tested
for BVDV by use of virus isolation (VI) and reverse
transcription-nested polymerase chain reaction (RTnPCR)
tests. Semen samples were tested for virus by
use of VI and RT-nPCR tests. Testicular biopsy specimens
were obtained 7 months after inoculation and
tested for BVDV by use of immunohistochemical
analysis and VI and RT-nPCR tests. Semen samples
collected from 1 bull immediately before and 5 and 7
months after inoculation were administered IV to
seronegative calves, which were monitored for subsequent
viremia and seroconversion.
Results—Use of VI and RT-nPCR tests detected transient
virus in serum of all bulls. The VI test detected
BVDV in semen of 2 bulls for < 21 days after inoculation,
whereas RT-nPCR assay detected BVDV until 7
months after inoculation. Virus was detected in testicular
biopsy specimens of these 2 bulls by use of
immunohistochemical analysis and RT-nPCR assay
but could only be isolated from the biopsy specimen
of 1 bull. Of the calves administered semen IV to
detect infectious virus, only the recipient of semen
collected 5 months after inoculation of the adult bull
was viremic and seroconverted.
Conclusions and Clinical Relevance—Bovine viral
diarrhea virus can persist in semen of acutely infected
bulls for several months after exposure.
(Am J Vet Res 2003;64:428–434)
Objective—To determine whether administration of 2 doses of a multivalent, modified-live virus vaccine prior to breeding of heifers would provide protection against abortion and fetal infection following exposure of pregnant heifers to cattle persistently infected (PI) with bovine viral diarrhea virus (BVDV) and cattle with acute bovine herpesvirus 1 (BHV1) infection.
Procedures—20 of 22 vaccinated and 10 of 11 unvaccinated heifers became pregnant and were commingled with 3 steers PI with BVDV type 1a, 1b, or 2 for 56 days beginning 102 days after the second vaccination (administered 30 days after the first vaccination). Eighty days following removal of BVDV-PI steers, heifers were commingled with 3 bulls with acute BHV1 infection for 14 days.
Results—After BVDV exposure, 1 fetus (not evaluated) was aborted by a vaccinated heifer; BVDV was detected in 0 of 19 calves from vaccinated heifers and in all 4 fetuses (aborted after BHV1 exposure) and 6 calves from unvaccinated heifers. Bovine herpesvirus 1 was not detected in any fetus or calf and associated fetal membranes in either treatment group. Vaccinated heifers had longer gestation periods and calves with greater birth weights, weaning weights, average daily gains, and market value at weaning, compared with those for calves born to unvaccinated heifers.
Conclusions and Clinical Relevance—Prebreeding administration of a modified-live virus vaccine to heifers resulted in fewer abortions and BVDV-PI offspring and improved growth and increased market value of weaned calves.
Objective—To determine the prevalence of bovine viral diarrhea virus (BVDV)–infected alpaca herds in the United States and investigate factors associated with seropositive herd status and, subsequently, determine the proportion of animals within seropositive alpaca herds that are persistently infected (PI) carriers for BVDV, obtain information regarding previous herd exposure to BVDV, determine titers of anti-BVDV antibodies of dams, and ascertain whether individual seropositive crias had received supplemental colostrum at birth.
Animals—63 alpaca herds with ≥ 12 registered female alpacas.
Procedures—250 alpaca breeders were randomly selected from 562 eligible herds listed in the Alpaca Owner and Breeders Association membership directory and mailed a voluntary participation request. Sixty-three alpaca breeders participated in the study. From each herd, blood samples from ≥ 4 crias were tested for BVDV, BVDV RNA, and serum neutralizing antibodies against BVDV. A region of the genome of BVDV recovered from PI crias was sequenced to determine genetic homology.
Results—Among the 63 herds, 16 (25.4%) had seropositive crias and 4 (6.3%) had PI crias. Infections in 3 of the 4 herds with PI crias were linked as evidence by the genetic homologies of viruses. In addition to PI crias, feeding supplemental colostrum was associated with herd seropositivity.
Conclusions and Clinical Relevance—Results confirmed the importance of BVDV infections in alpacas in the United States and highlighted the importance of determining the BVDV infection status of animals before they are commingled to limit exposure of herds to BVDV infection.