PCR detection of colostrum-associated Maedi-Visna virus (MVV) infection and relationship with ELISA-antibody status in lambs

Álvarez, Vega; Daltabuit-Test, Mara; Arranz, J.; Leginagoikoa, I.; Juste, Ramón A.; Amorena, B.; Andrés, D. de; Luján, Lluís; Badiola, Juan José; Berriatua, E.

doi:10.1016/j.rvsc.2005.05.008

Cited by 56 publications

(66 citation statements)

References 22 publications

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“…This is the first study comparing the MVV-seroprevalence in intensive semiintensive and extensive commercial sheep flocks in an MVV-endemic country and was carried out to provide some field evidence that horizontal transmission is the key route for MVV-infection and that lactogenic transmission alone may be insufficient to insure MVV-persistence in infected flocks, as suspected from previous experimental studies [2,3,17]. The results obtained strongly suggest that in sheep production systems where sheep do not have close contact, MVV-transmission is scarce and the opposite occurs when sheep are confined together most of the time.…”

Section: Discussionmentioning

confidence: 90%

“…Seroprevalence (95% CI) in males and females was, respectively, 75% and 77% in intensive flocks (p > 0.05), 19% and 25% in semi-intensive flocks (p < 0.05) and 8% (3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14) and 5% (4-6) in extensive flocks (p > 0.05).…”

Section: Mvv-seroprevalencementioning

confidence: 93%

“…However, different numbers of flocks from each system were selected because average flock sizes varied between systems, there was no data on seroprevalence of MVV-infection in the extensive Manchega cross-bred flocks and it was necessary to accommodate the study design to detect MVV in this system. Furthermore, given the good knowledge of the epidemiology of MVV-infection in semiintensive Latxa flocks available [2,3,6,17], it was decided to allocate more resources to investigating MVV in other sheep production systems.…”

Section: Study Design and Populationmentioning

confidence: 99%

“…Moreover, there is some recent evidence that SRLV-infection is low or even absent in extensively reared sheep flocks and goat herds in Patagonia [25,26]. The risk of lactogenic SRLV-infection has only been partially quantified and the percentage of naturally raised lambs that become infected from suckling colostrum from seropositive dams has been estimated at approximately only 20% [2,3]. If the risk of lactogenic infection during the preweaning period is below 1 (100%) then it is evident that some other form of infection is necessary to achieve an R e (effective reproduction ratio: average number of secondary infections produced by one infected individual) value above one, necessary for infection to last in the population [4].…”

Section: Introductionmentioning

confidence: 99%

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Extensive rearing hinders Maedi-Visna Virus (MVV) infection in sheep

et al. 2006

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-Maedi-Visna Virus (MVV) seroprevalence and its relationship with housing and mode of rearing of replacement ewe-lambs was investigated in 38 non-randomly selected sheep-flocks in Spain. They included extensive lamb-producing Manchega cross-bred flocks raised almost permanently at pasture, semi-intensive Latxa dairy flocks housed 2-8 months/year and intensively raised Assaf dairy flocks housed most time and at higher stocking density in less ventilated buildings than other flocks. Most flocks raised replacement lambs naturally with their dams until weaning and as a separate flock thereafter until lambing at one year of age. Seroprevalence (95% confidence intervals) was 77%, 25% and 5% (4-6) in intensive, semi-intensive and extensive flocks, respectively and the median (interquartile range) flock-seroprevalence was 82% (66-94) in intensive flocks, 31% (14-31) in semi-intensive flocks and 4% (0-7) in extensive flocks. Seroprevalence was lowest in one year-old sheep and increased to flock levels during the year after introduction into the adult flock in most intensive flocks and more gradually in other flocks. Adult flock seroprevalence was associated with housing time but this relationship was not evident within a particular rearing system, indicating that other unknown factors are critical in horizontal MVV-transmission. Low seroprevalence in extensive flocks further supports previous indications that lactogenic MVV-infection is relatively inefficient and horizontal transmission is necessary to ensure long-term maintenance of MVV and this could explain that MVV has not been reported from countries with mainly extensively reared sheep such as Australia and New Zealand. Moreover, it indicates that MVV-control in extensive and semi-intensive flocks can be simple and inexpensive.Maedi-Visna Virus / sheep / seroprevalence / intensive and extensive rearing / Spain

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Section: Discussionmentioning

confidence: 90%

Section: Mvv-seroprevalencementioning

confidence: 93%

Section: Study Design and Populationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Extensive rearing hinders Maedi-Visna Virus (MVV) infection in sheep

et al. 2006

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“…Different studies have used molecular or serological methods such as PCR, ELISA and AGID in order to survey the presence of MVV in milk samples [5,6,8,9,14,15]. Unfortunately, serological methods aren't able to detect infected animals prior to seroconversion, and the result of the tests cannot be interpreted during the first 6 months of life because of passively acquired antibodies in non-infected offspring [16]. Presence of SRLV antibodies in ovine milk was detected by Ploumi et al [17], which indicated that MVV-seropositive sheep flocks are commonly associated with mastitis incidence.…”

Section: Discussionmentioning

confidence: 99%

Study on Correlation of Maedi-Visna Virus (MVV) with Ovine Subclinical Mastitis in Iran

et al. 2013

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Maedi-Visna is an important slow viral disease of sheep leading to progressive pneumonia, encephalitis and mastitis. Udder is one of the organs affected by MVV. Despite the fact that in Iran Maedi-Visna is known since 2000, to the authors' knowledge correlation of subclinical mastitis and infection with MVV has not been assayed. In this study 50 milk samples from 10 flocks in East Azerbaijan Province of Iran were tested. None of the animals exhibited any clinical signs of the disease. Forty samples were collected from CMT positive ewes and ten were taken from CMT negative ewes. Milk samples were analyzed using PCR targeting gag sequence. Presence of provirus DNA was detected in one sample from CMT negative and seven samples from CMT positive ewes. These data demonstrate that 16.5 % of sheep with subclinical mastitis were infected to MVV. Thus this virus can be considered one of the main pathogenic agents of mastitis and can be dramatically transmitted to lambs by milk.

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Visna in a UK flock and the biosecurity risk arising from the onward sale of likely infected pedigree stock

Evans

Caldow²,

Del-Pozo

et al. 2021

Vet Record Case Reports

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Small Ruminant Lentivirus infections in sheep most commonly present with respiratory signs (maedi) and indurative mastitis, while primary neurological signs (visna) have rarely been reported in Great Britain. Most reports of visna describe signs referable to myelitis, although central signs associated with encephalitis may feature. In this case, visna was diagnosed in a 4-year-old ewe in a small pedigree sheep flock, recently imported to GB from northern Europe. Initial clinical findings were of a head tilt, circling, facial tremors and a unilaterally reduced menace response. These neurological signs progressed to include hyperaesthesia, ipsilateral hemiparesis and recumbency. Flock level infection had recently been diagnosed by serology, and the diagnosis in this individual case was confirmed by serology and histopathology. The subsequent sale of animals from the flock through a large national auction and at private sales raises significant ethical questions and serves as a reminder of the importance of biosecurity precautions.

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PCR detection of colostrum-associated Maedi-Visna virus (MVV) infection and relationship with ELISA-antibody status in lambs

Cited by 56 publications

References 22 publications

Extensive rearing hinders Maedi-Visna Virus (MVV) infection in sheep

Extensive rearing hinders Maedi-Visna Virus (MVV) infection in sheep

Study on Correlation of Maedi-Visna Virus (MVV) with Ovine Subclinical Mastitis in Iran

Visna in a UK flock and the biosecurity risk arising from the onward sale of likely infected pedigree stock

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