Rapid Transplacental Infection with Bovine Pestivirus Following Intranasal Inoculation of Ewes in Early Pregnancy

Abstract

Abstract. Despite the importance of congenital viral infections in both veterinary and human medicine, only limited experimental work has been carried out to elucidate the mechanisms involved in transplacental virus infections. To further an understanding of fetal infection with pestiviruses, the distribution of bovine pestivirus in the uterine and fetal tissues of ewes in early pregnancy, following a natural route of infection, was investigated. On the 18th day of pregnancy, nine ewes were inoculated by the intranasal route with 1 ϫ 10 5 50% tissue culture infective doses of an Australian isolate of noncytopathic bovine pestivirus (bovine viral diarrhea virus genotype 1). All ewes were ovariohysterectomized at approximately 100 hours postinfection. Samples from the reproductive tract and conceptus were examined histologically and tested for bovine pestivirus by nested reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry and for interferon-tau mRNA expression by nonnested RT-PCR. Although no histopathologic changes were observed in the maternal or fetal tissues, virus was detected in the reproductive tract of all nine ewes and in all of the conceptuses examined. At the time of surgery, only two of the nine ewes were demonstrably viremic. This study demonstrates that bovine pestivirus can spread from a natural site of infection to the ovine fetus within 4 days in the absence of maternal immunity and despite the presence of interferon expression in the reproductive tract.

Experimental infection of pregnant goats with bovine viral diarrhea virus (BVDV) 1 or 2

“…Infections in pregnant small ruminants may result in uteroplacental pathology and pregnancy loss by fetal resorption or abortions [9]. In sheep, BVDV rapidly crosses the placental barrier, and the virus was detected in fetal tissues by RT-PCR and immunohistochemistry approximately 100 h following infection [20]. While transplacental BVDV infection in sheep can result in pregnancy losses and non-viability of lambs, reports of viable PI offspring are also common [6,21].…”

Innate Immune Responses of Calves during Transient Infection with a Noncytopathic Strain of Bovine Viral Diarrhea Virus

“…BVDV is unusual due to the existence of two differing biotypes, namely, cytopathic (cpBVDV) and noncytopathic (ncpBVDV) virus types. Following transplacental infection during the first trimester of gestation, ncpBVDV is likely to provoke in the immunologically immature fetus a state of viral immunotolerance leading to lifelong virus persistence (52,53). Persistently infected animals usually succumb to mucosal disease later in life either upon superinfection with or endogenous generation of an antigenically homologous cpBVDV (55,57).…”

Role of bovine viral diarrhea virus biotype in the establishment of fetal infections

“…Ribonucleic acid transcripts were electroporated into RD420 cells to recover live BVDV, as described. Ten cows were inoculated via intranasal aerosol of 10 mL of cell culture supernatant containing 10 7 median tissue culture infective doses (TCID 50 ) of i-VVNADL (ie, infectious clone-derived BVDV) or NADL-A (ie, wild-type BVDV a ). c Viruses were titered by endpoint dilution in RD420 cells, as described.…”