WAVLD Symposium Handbook_V4.indd - csiro

World Association of Veterinary Laboratory Diagnosticians – 13 th International Symposium, Melbourne, Australia, 11-14 November 2007
HOW MANY PESTIVIRUSES CIRCULATE IN NATURE? PESTIRUSES IN FREE-LIVING ANIMALS:
PRESENT STATUS AND PROBLEMS
S.Vilcek 1* , P.F. Nettleton 2
1 University of Veterinary Medicine, Kosice, Slovakia; 2 Moredun Research Institute, Pentlands Science Park, Penicuik, Midlothian EH26
0PZ, UK
Four pestivirus species infect domestic animals. BVDV-1 and BVDV-2 mostly infect cattle, CSFV – swine,
BDV – sheep. Pestiviruses are not strictly host specific because they can infect many other animals. Genetic
analysis of pestiviruses by rapid sequencing of PCR products coupled with phylogenetic analysis revealed
new viral genotypes, some of them in free-living animals.
Mainly BVDV specific antibodies have been reported in captive and free-living animals. Pestivirus specific
antibodies were detected in over 40 animal species but the isolation of viruses from wild animals is relatively
rare. It is generally known that CSFV infects not only domestic pigs but also wild boars which are significant
reservoirs of this virus. The BVDV-1 isolates were already detected for example in deer, roe deer, mouse
deer, lama, yak, eland, buffalo, bison. Recently, a pestivirus isolated from reindeer has been typed as BDV-2
genotype (Becher et al., 2003). Pestivirus identified in chamois has been typed as BDV-4 genotype causing
significant problems in chamois population in Pyrenees (Arnal et al., 2004). The first giraffe pestivirus strain
was identified in 60-ties, the second giraffe strain just several years ago. Both strains belong to the
unclassified pestivirus species and in the phylogenetic analysis form a giraffe pestivirus genotype (Avalos-
Raminez et al., 2001). Pestivirus isolated from a pronghorn antelope found dead in Wyoming (Vilcek et al.,
2005) as well as recently identified Bungowannah pestivirus in pig (Kirkland et al., 2007) are representants of
two most distinct pestivirus genotypes so far.
All together six pestivirus genotypes (CSFV, BVDV-1, BDV-2, BDV-4, giraffe and pronghorn antelope) have
been identified in wild animal population. Viruses of BVDV-2, BDV-1 or BDV-3 genotype infecting mostly
cattle and sheep have not been found in wild animals yet.
Most data presented in scientific literature suggest that pestivruses are more likely transmitted from domestic
animals to wildlife population. The transmission in opposite way is not exactly proved but theoretically it can
not be excluded that transmission of highly virulent pestivirus strain from domestic to wild animals or vice
versa could have a devastating effect on the eradication programmes as well as on wildlife population.
There are potential problems with the identification of new pestiviruses:
i/ selection of the correct virus for use in serological studies
ii/ use of the correct cells for the isolation of new pestiviruses
iii/ proper selection of RT-PCR primers for the detection of new pestivirus genomes
All data suggest that pestiviruses are highly efficient viruses infecting domestic and many free-living animal
species and they evolved well-adapted strategy to survive in nature. Taking into account present status with
the identification of new pestiviruses we can conclude that wild animals may be infected with more
pestiviruses than we have identified at present. No doubt that there is a need for more systematic research
focused on the occurrence of pestiviruses in free-living animals.
References
Arnal, M., et al.: J. Gen. Virol., 85, 3653, 2004.
Avalos-Raminez, R., et al.: Virology 286, 456, 2001.
Becher, P., et al.: Virology 311, 96, 2003.
Kirkland, P.D. et al. : Virus Res., 129, 26, 2007.
Vilcek S., et al.: Virus Res., 108, 187, 2005.
Mon 12 November
Mon 12 November
World Association of Veterinary Laboratory Diagnosticians – 13 th International Symposium, Melbourne, Australia, 11-14 November 2007
CHARACTERIZATION AND DETECTION OF BVDV RELATED
REPRODUCTIVE DISEASE IN WHITE-TAILED DEER
J.F. Ridpath 1* , E.A. Driskell 2 , C.C. Chase 3 , J.D. Neill 1
1 NADC/ARS/USDA, Ames, IA, 2 University of Georgia, Athens, GA, 3 South Dakota State University, Brookings, SD
Introduction
Bovine viral diarrhea viruses (BVDV) are the causative agent of reproductive and respiratory disease in
cattle resulting in significant economic loss to the beef and dairy industries. The primary consequences of
reproductive infection are due to the direct infection of the fetus and the outcome depends on the stage of
gestation in which the fetal infection occurs 1 . Although abortions and weak calves have been attributed to
BVDV infection in late gestation 6 , infections occurring earlier in gestation generally have greater impact.
Fetal infections in cattle, occurring during the first trimester, result in fetal reabsorption, mummification,
abortion or the establishment of persistently infected (PI) animals. PI cattle are considered the main vector
for introduction of the virus to naïve herds.
BVDV also replicates in white-tailed deer (Odocoileus virginianus) 2-5 . Free ranging white-tailed deer
populations are frequently in contact with domestic cattle in the U.S., therefore, possible transfer of BVDV
between cattle and deer has significant implications for proposed BVDV control programs. The goal of this
study was to examine the effects of BVDV infection in pregnant white-tailed deer
Material & methods
Eleven white-tailed does were purchased from a commercial breeder and housed in BSL2 containment.
Pregnancy status was confirmed and the calculated stage of pregnancy was based on date of contact with
buck. Does were inoculated with one of two BVDV previously recovered from wild white-tailed deer. Levels
of BVDV neutralizing serum antibodies were determined prior to inoculation and 21 or 35 days post
inoculation. Virus isolation was performed on tissues from aborted fetuses, tissues from does that died and
from blood samples from live fawns. Additionally, ear notches of live fawns were tested for BVDV antigen by
antigen capture ELISA (ACE).
Results
Two of the does had serum antibody titers against BVDV (>512) prior to inoculation; the remaining 9 does
were seronegative. Both seropositive animals gave birth to normal fawns. Of the remaining 9 seronegative
animals, one was not pregnant at the start of the study, four died (death between 8 to 79 days post
inoculation), one apparently readsorbed its fetus, two aborted and one gave birth to two probable PI fawns.
BVDV was isolated from fetuses, maternal tissues and PI fawns. Ear notches of PI fawns were positive by
ACE.
Discussions & conclusions
Following BVDV infection of deer we confirmed infection of fetal tissues within the first 7 – 8 days of
infection. We observed abortion and mummification following infection and the birth of apparently
persistently infected fawns. The fawns of does that had serum neutralizing antibodies against BVDV at the
time of inoculation were protected. These observations are consistent with the clinical presentation of BVDV
associated reproductive disease in cattle following exposure before 125 days gestation. Further research
needs to be done to determine if the similarities between BVDV associated reproductive disease in whitetailed
deer and cattle hold at later stages of gestation and to determine, more exactly, the window of fetal
vulnerability for development of persistent BVDV infection in white-tailed deer.
References
1 Brock KV, Grooms DL, Givens MD: 2005, Reproductive disease and persistent infections. In: Bovine viral
diarrhea virus: diagnossis, management and control, eds. Goyal SMRidpath JF, pp. 145-156.
Blackwell Publishing, Ames, IA.
2 Chase CCL, Braun LJ, Leslie-Steen P, et al.: 2007, Evidence of bovine viral diarrhea virus persistent
infection in two white-tailed deer in southeastern South Dakota. Journal of Wildlife Diseases In
press.
3 Passler T, Walz PH, Ditchkoff SS, et al.: 2007, Experimental persistent infection with bovine viral diarrhea
virus in white-tailed deer. Vet Microbiol 122:350-356.
4 Ridpath JF, Mark CS, Chase CCL, et al.: 2007, Febrile response and decrease in circulating lymphocytes
following acute infection of white tail deer fawns with either a BVDV1 or a BVDV2 strain Journal of
Wildlife Diseases 43:In press.
5 Van Campen H, Williams ES, Edwards J, et al.: 1997, Experimental infection of deer with bovine viral
diarrhea virus. J Wildl Dis 33:567-573.
6 Ward GM, Roberts SJ, McEntee K, Gillespie JH: 1969, A study of experimentally induced bovine viral
diarrhea-mucosal disease in pregnant cows and their progeny. Cornell Vet 59:525-538.