Investigation of risk factors associated with infections caused by small ruminant lentiviruses

Barquero, N.; Gómez-Lucı́a, Esperanza; Arjona, Álvaro; Toural, Cristina; Heras, Ángeles; Fernández‐Garayzábal, J. F.; Quiteria, Jose Antonio Ruíz-Santa; Doménech, Ana

doi:10.2478/bvip-2013-0082

Cited by 14 publications

(18 citation statements)

References 24 publications

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“…The possibility that inflammation produced by pathologies other than SRLV infection (bacterial infection, traumatism, etc. ) and increased somatic cell counts (SCC) would affect proviral detection has been analysed in other study, where we found no association between PCR results and the SCC or presence of mastitis [26]. A third possibility could be the intermittent shedding of provirus due to seasonal factors, or even to pregnancy and lactation.…”

Section: Discussionmentioning

confidence: 87%

Evolution of Specific Antibodies and Proviral DNA in Milk of Small Ruminants Infected by Small Ruminant Lentivirus

Barquero

Gómez-Lucı́a

Arjona

et al. 2013

Viruses

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The diagnosis of Small Ruminant Lentivirus (SRLV) is based on clinical signs, pathological lesions and laboratory testing. No standard reference test for the diagnosis of maedi visna has been validated up to the present, and it is puzzling that tests which detect antibodies against the virus and tests which detect the proviral genome may render opposite results. The aim of this study was to evaluate the presence in milk throughout a lactation period of specific antibodies by ELISA and of SRLV proviral DNA by a PCR of the highly conserved pol region. A six-month study was conducted with the milk of 28 ewes and 31 goats intensively reared. The percentage of animals with antibodies against SRLV increased throughout the study period. Seroprevalence in sheep was 28% at the beginning of the study and by the end it had increased up to 52.4%. In goats, initial seroprevalence of 5.6% increased to 16%. The percentage of PCR positive ewes was stable throughout the study period. Of the positive sheep, 21.4% were PCR-positive before antibodies could be detected and most of them became PCR-negative shortly after the first detection of antibodies. This might suggest that antibodies have a neutralizing effect. In addition, an equal percentage of sheep were always PCR-negative but either became ELISA-positive or was always ELISA-positive, which might support this hypothesis. On the other hand, the PCR results in goats did not follow any pattern and oscillated between 35.3% and 55.6% depending on the month. Most goats positive by PCR failed to develop antibodies in the 6 months tested. We may conclude that the infection and the antibody response to it follow a different trend in sheep and goats.

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Section: Discussionmentioning

confidence: 87%

Evolution of Specific Antibodies and Proviral DNA in Milk of Small Ruminants Infected by Small Ruminant Lentivirus

Barquero

Gómez-Lucı́a

Arjona

et al. 2013

Viruses

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“… 1 In addition, there are uncertainties that they are functionally important in vivo, since SRLVs are cell-associated viruses and can spread by cell-to-cell contact, and neutralization may not interfere with viral spread. 1 , 46 Even though the humoral response is not enough to eliminate the viral infection (which is lifelong lasting), some studies have shown that it limits the spread of the viruses. 47 Antibodies do not always help fighting against the infection.…”

Section: The Virus Spreads – and The Body Reactsmentioning

confidence: 99%

“…Exercise intolerance is one of the first clinical signs to be noticed, followed by dyspnea at rest, accompanied by abdominal breathing, neck extension, expansion of the nostrils, and breathing with mouth open. 46 As the disease progresses, the animal suffers from anorexia, weight loss, and finally cachexia. Nasal exudate appears only when there are secondary bacterial infections.…”

Section: The Virus Spreads – and The Body Reactsmentioning

confidence: 99%

“…The prevalence is much higher in developed countries, which seems to be related to the system of feeding lambs or kids with a pool of colostrum or milk from the tank, a practice that favors transmission, 6 and to the management system. 7 , 8 …”

Section: Introductionmentioning

confidence: 99%

“…The route of transmission is related to body fluids, mainly respiratory exudates and milk or colostrum, which may contain infected monocytes and macrophages. 9 The main transmission routes are airborne, favored by overcrowding (stabling), 7 and milk borne. 10 , 11 It is not clear if the transmission among animals occurs through the presence of free virions and/or through infected cells.…”

Section: Introductionmentioning

confidence: 99%

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Maedi-Visna virus: current perspectives

Gómez-Lucı́a

Barquero

Doménech

2018

VMRR

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Maedi-Visna virus (MVV) and caprine arthritis-encephalitis virus are commonly known as small ruminant lentiviruses (SRLVs) due to their genetic, structural, and pathogenic similarities. They produce lifelong lasting infections in their hosts, which are characterized by slow progression till overt disease happens. There are four major clinical forms derived from a chronic inflammatory response due to the constant low grade production of viruses from monocyte-derived macrophages: respiratory (caused by interstitial pneumonia), mammary (which may produce a decrease in milk production due to subclinical mastitis), joint (characterized by lameness), and neurological (characterized by chronic nonpurulent meningoencephalomyelitis). There are three levels which try to eliminate the virus: cellular, body, and the flock level. However, SRLVs have ways to counteract these defenses. This review examines some of them.

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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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Investigation of risk factors associated with infections caused by small ruminant lentiviruses

Cited by 14 publications

References 24 publications

Evolution of Specific Antibodies and Proviral DNA in Milk of Small Ruminants Infected by Small Ruminant Lentivirus

Evolution of Specific Antibodies and Proviral DNA in Milk of Small Ruminants Infected by Small Ruminant Lentivirus

Maedi-Visna virus: current perspectives

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

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