TY - JOUR

T1 - Transplacental transmission of field and rescued strains of BTV-2 and BTV-8 in experimentally infected sheep

AU - Rasmussen, Lasse Dam

AU - Savini, Giovanni

AU - Lorusso, Alessio

AU - Bellacicco, Anna

AU - Palmarini, Massimo

AU - Caporale, Marco

AU - Rasmussen, Thomas Bruun

AU - Belsham, Graham J

AU - Bøtner, Anette

PY - 2013/9/5

Y1 - 2013/9/5

N2 - Transplacental transmission of bluetongue virus has been shown previously for the North European strain of serotype 8 (BTV-8) and for tissue culture or chicken egg-adapted vaccine strains but not for field strains of other serotypes. In this study, pregnant ewes (6 per group) were inoculated with either field or rescued strains of BTV-2 and BTV-8 in order to determine the ability of these viruses to cross the placental barrier. The field BTV-2 and BTV-8 strains was passaged once in Culicoides KC cells and once in mammalian cells. All virus inoculated sheep became infected and seroconverted against the different BTV strains used in this study. BTV RNA was detectable in the blood of all but two ewes for over 28 days but infectious virus could only be detected in the blood for a much shorter period. Interestingly, transplacental transmission of BTV-2 (both field and rescued strains) was demonstrated at high efficiency (6 out of 13 lambs born to BTV-2 infected ewes) while only 1 lamb of 12 born to BTV-8 infected ewes showed evidence of in utero infection. In addition, evidence for horizontal transmission of BTV-2 between ewes was observed. As expected, the parental BTV-2 and BTV-8 viruses and the viruses rescued by reverse genetics showed very similar properties to each other. This study showed, for the first time, that transplacental transmission of BTV-2, which had been minimally passaged in cell culture, can occur; hence such transmission might be more frequent than previously thought.

AB - Transplacental transmission of bluetongue virus has been shown previously for the North European strain of serotype 8 (BTV-8) and for tissue culture or chicken egg-adapted vaccine strains but not for field strains of other serotypes. In this study, pregnant ewes (6 per group) were inoculated with either field or rescued strains of BTV-2 and BTV-8 in order to determine the ability of these viruses to cross the placental barrier. The field BTV-2 and BTV-8 strains was passaged once in Culicoides KC cells and once in mammalian cells. All virus inoculated sheep became infected and seroconverted against the different BTV strains used in this study. BTV RNA was detectable in the blood of all but two ewes for over 28 days but infectious virus could only be detected in the blood for a much shorter period. Interestingly, transplacental transmission of BTV-2 (both field and rescued strains) was demonstrated at high efficiency (6 out of 13 lambs born to BTV-2 infected ewes) while only 1 lamb of 12 born to BTV-8 infected ewes showed evidence of in utero infection. In addition, evidence for horizontal transmission of BTV-2 between ewes was observed. As expected, the parental BTV-2 and BTV-8 viruses and the viruses rescued by reverse genetics showed very similar properties to each other. This study showed, for the first time, that transplacental transmission of BTV-2, which had been minimally passaged in cell culture, can occur; hence such transmission might be more frequent than previously thought.

KW - Animals

KW - Antibodies, Viral/analysis

KW - Bluetongue/transmission

KW - Bluetongue virus/genetics

KW - Cells, Cultured

KW - Ceratopogonidae/virology

KW - Choroid Plexus/virology

KW - Female

KW - Infectious Disease Transmission, Vertical/veterinary

KW - Milk/virology

KW - Placenta/virology

KW - Polymerase Chain Reaction/veterinary

KW - Pregnancy

KW - Sheep

KW - Sheep Diseases/transmission

U2 - 10.1186/1297-9716-44-75

DO - 10.1186/1297-9716-44-75

M3 - Journal article

C2 - 24007601

VL - 44

SP - 75

JO - Veterinary Research

JF - Veterinary Research

SN - 0928-4249

ER -