title: PCR detection of colostrum-associated Maedi-Visna virus (MVV) infection and relationship with ELISA-antibody status in lambs.
abstract: 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.
authors.affiliation: Instituto Vasco de Investigación y Desarrollo Agrario (NEIKER), Sanidad Animal, 48160-Derio, Vizcaya, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Alvarez
authors.forename: M
authors.initials: M
authors.lastname: Daltabuit-Test
authors.forename: J
authors.initials: J
authors.lastname: Arranz
authors.forename: I
authors.initials: I
authors.lastname: Leginagoikoa
authors.forename: R A
authors.initials: RA
authors.lastname: Juste
authors.forename: B
authors.initials: B
authors.lastname: Amorena
authors.forename: D
authors.initials: D
authors.lastname: de Andrés
authors.forename: Ll
authors.initials: L
authors.lastname: Luján
authors.forename: J J
authors.initials: JJ
authors.lastname: Badiola
authors.forename: E
authors.initials: E
authors.lastname: Berriatua
mesh_terms: 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*
chemical_list: D000914:Antibodies, Viral