Modulation of sex hormone secretion in cows by acute infection with bovine viral diarrhoea virus.
Bovine viral diarrhoea virus (BVDV) is a major pathogen of cattle and is responsible for considerable reproductive loss. In this study, the in vivo responses in six multiparous cows were investigated after a non-cytopathogenic BVDV challenge (strain Pe 515; 5 x 10(6) tissue culture infective dose 50) given 9 days before a synchronized ovulation. Six similar cows challenged with non-infectious culture medium served as controls. The experimental noncytopathogenic BVDV infection was followed by a viraemia and leucopenia at days 5-9 after challenge, but no other clinical signs of infection were detected. However, the BVDV infection altered endocrine function. Mean LH pulse frequency immediately before CIDR withdrawal was lower (P < or = 0.05) in the BVDV-infected (2.17 +/- 0.34 pulses per 8 h) compared with the sham-infected (4.83 +/- 1.04 pulses per 8 h) animals. At day 3 after CIDR withdrawal, plasma oestradiol concentrations remained high (P < 0.05) in the infected cows (2.19 +/- 0.51 pg ml(-1)) compared with the sham-infected controls (0.72 +/- 0.29 pg ml(-1)). However, there was no difference in the peak oestradiol concentration (BVDV: 2.31 +/- 0.29 versus sham: 2.34 +/- 0.41 pg ml(-1)). In addition, non-cytopathogenic BVDV significantly (P < 0.05) increased the duration of the interval between ovulation and onset of the postovulatory progesterone increase (values 1.0 ng ml(-1)) (BVDV: 3.0 +/- 0.26 versus sham: 4.0 +/- 0.26 days). The viral infection also significantly (P < 0.01) decreased mean plasma progesterone concentrations between day 3 and day 11 after ovulation (BVDV: 2.59 +/- 0.32 versus sham: 4.13 +/- 0.27 ng ml(-1)). These data show that non-cytopathogenic BVDV viraemias during the follicular phase can modulate the secretion of gonadotrophins and sex steroids, in particular progesterone, during a synchronized oestrous cycle. Therefore, viraemias during the follicular phase may reduce the fertility of cattle by disrupting the capacity of the ovulatory follicle to form a competent corpus luteum, thereby compromising early embryo development and maternal recognition of pregnancy.
Fray
M D
MD
Institute for Animal Health, Compton, Newbury RG20 7NN, UK. m.fray@har.mrc.ac.uk
Mann
G E
GE
Bleach
E C L
EC
Knight
P G
PG
Clarke
M C
MC
Charleston
B
B
D000208:Acute Disease; D000704:Analysis of Variance; D000818:Animals; D000956:Antigens, Viral / Q000032:analysis; D001912:Bovine Virus Diarrhea-Mucosal Disease / Q000097:blood / Q000276:immunology / Q000503:physiopathology*; D002417:Cattle; D030241:Diarrhea Virus 1, Bovine Viral; D004958:Estradiol / Q000097:blood / Q000378:metabolism; D030762:Estrous Cycle / Q000097:blood; D004973:Estrus Synchronization; D005260:Female; D012739:Gonadal Steroid Hormones / Q000097:blood / Q000378:metabolism*; D007986:Luteinizing Hormone / Q000378:metabolism; D010053:Ovary / Q000276:immunology; D011374:Progesterone / Q000097:blood / Q000378:metabolism; D011897:Random Allocation; D014766:Viremia / Q000276:immunology / Q000503:physiopathology*
D000956:Antigens, Viral; D012739:Gonadal Steroid Hormones; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone