PCR detection of colostrum-associated Maedi-Visna virus (MVV) infection and relationship with ELISA-antibody status in lambs.
A recent large-scale experimental study showed that bottle-feeding ovine colostrum from seropositive ewes results in high MVV-seroconversion in lambs. In contrast, relatively few lambs that naturally suckled colostrum from seropositive dams seroconverted as a result of it. Furthermore, lambs fed uninfected bovine colostrum readily seroconverted when mixed with ovine-colostrum lambs indicating that horizontal MVV transmission between lambs was efficient. MVV-infection was further investigated in the same samples using two PCR tests targeting sequences in the long-terminal repeats (LTR) and POL MVV genes. PCR-tests confirmed previous serological findings. However, the LTR-PCR was more sensitive and allowed detecting infection earlier than the other tests, including 5-8% of new-born lambs from seropositive dams, providing more evidence that prenatal MVV-infection may be more important than considered. The degree of agreement between PCR and antibody tests in individual samples was low up to 6 months of age and moderate at 10 months-old. Nine percent of lambs were always PCR-negative but seroconverted and 19% of lambs were PCR-positive at least once and did not seroconvert. However, seroconversion was associated with increasing number of times lambs were PCR-positive and ovine colostrum-fed lambs were more frequently PCR-positive than other lambs. The significance of these findings in terms of MVV-infection, epidemiology and control is discussed.
Alvarez
V
V
Instituto Vasco de Investigación y Desarrollo Agrario (NEIKER), Sanidad Animal, 48160-Derio, Vizcaya, Spain.
Daltabuit-Test
M
M
Arranz
J
J
Leginagoikoa
I
I
Juste
R A
RA
Amorena
B
B
de Andrés
D
D
Luján
Ll
L
Badiola
J J
JJ
Berriatua
E
E
D000375:Aging; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D003126:Colostrum / Q000821:virology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D005260:Female; D018445:Infectious Disease Transmission, Vertical / Q000662:veterinary*; D008297:Male; D016017:Odds Ratio; D011021:Pneumonia, Progressive Interstitial, of Sheep / Q000097:blood / Q000276:immunology* / Q000635:transmission* / Q000821:virology; D016133:Polymerase Chain Reaction / Q000662:veterinary; D012756:Sheep; D014790:Visna-maedi virus / Q000235:genetics* / Q000302:isolation & purification*
D000914:Antibodies, Viral