Ovine lentivirus induced indurative lymphocytic mastitis and its effect on the growth of lambs

Pekelder, J. J.; Veenink, G. J.; Akkermans, J. P. W. M.; Eldik, P. van; Elving, L.D.; Houwers, D. J.

doi:10.1136/vr.134.14.348

Cited by 43 publications

(25 citation statements)

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“…In the present study positive correlation were demonstrated between CMT and infection. This result is in agreement with Pekelder et al [19] who indicated that MVV infection increases SCC in sheep. It is reported that PCR has a sensitivity and specificity of 94.7 and 84.5 %, respectively, relative to the p28 ELISA [20].…”

Section: Discussionsupporting

confidence: 83%

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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Section: Discussionsupporting

confidence: 83%

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

et al. 2013

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“…For an average weight of animals around 30 kg, the weight loss estimated in this study is a much smaller percentage (2% to 8%) of live weight than found for other sheep diseases (Kirkwood, 1980;Coop et al, 1985;Pekelder, 1994;Sargison et al, 1995;Mackay et al, 1998). The effect is similar to a 6.7% reduction in lamb output due to footrot in ewes estimated from results presented by Symons (1978) but much lower than the 30% found by Stewart et al (1984).…”

Section: Discussioncontrasting

confidence: 59%

“…For example, estimates of the reduction of live weight in lambs infected with internal parasites range from 6.2% to 23% (Coop et al, 1985;Mackay et al, 1998). Sheep scab leads to a 53% reduction in growth rate in lambs (Kirkwood, 1980) and a 10% loss in birth weight (Sargison et al, 1995), while losses in lamb weaning weight due to Maedi-Visna have been estimated at 12% for the most severe cases (Pekelder, 1994). Based on results of Symons (1978) and Stewart et al (1984) it can be estimated that ewes infected with footrot have a reduced lamb output of 18%.…”

Section: Introductionmentioning

confidence: 99%

The effect of footrot on weight gain in sheep

Nieuwhof¹,

Bishop

Hill

et al. 2008

Animal

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Footrot is a highly contagious bacterial disease of sheep affecting the interdigital skin and surrounding soft and hard horn of a hoof, often resulting in severe lameness. This study was aimed at estimating the effect of footrot on weight gain of affected animals, and characterising the variation between animals in terms of phenotypic, environmental and genetic components. A general approach was developed describing the relationship between the disease and weight gain, defining new traits such as the maximum weight loss as a result of disease and the time after infection that this occurs. In two trials, 1267 Merino sheep were artificially challenged with footrot when 10 months old and re-infected through exposure to footrot on pasture 33 weeks later. Their feet were scored for footrot and live weights were measured approximately every 3 weeks. From data on animals that were not affected by footrot throughout each trial, normal growth curves were calculated and applied to affected animals to predict their growth had they remained healthy, so that weight loss as a result of footrot could be predicted. Animals with average footrot severity in the two trials suffered weight losses of 0.5 to 2.5 kg live weight, but most animals regained lost live weight later in the trials as footrot healed following vaccination. The estimates of the heritabilities of weight loss, adjusted for the severity of footrot, were about 0.30 and 0.15 in the experimental and natural challenge groups, respectively. Animals with higher genotypic values for weights at the start of each trial appeared to cope better with infections, in terms of lower weight losses. The time of highest footrot score and the time of maximum weight loss after infection had only very small genetic components.

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“…This type of mastitis is clinically difficult to detect and mainly consists in a diffuse hardening of the mammary gland often observed after parturition [12,25,26]. The main clinical sign is the lack of milk production, which is normally detected by a deficient growth of the lamb [34]. In all the target organs, lesions appear to be the consequence of viral replication in tissue macrophages [35].…”

Section: Introductionmentioning

confidence: 99%

Maedi-visna virus infection of ovine mammary epithelial cells

et al. 2006

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-The aim of this work was to perform a complete study of maedi-visna virus (MVV) infected mammary glands of naturally-infected sheep, and to determine if cells other than macrophages undergo a productive viral infection in this organ. Fifteen seropositive and two seronegative ewes were selected from MVV-infected flocks on the basis of clinical indurative mastitis and three sheep from an MVV-free flock. Within the mammary gland, MVV-positive cells were located by immunohistochemistry in the stroma and the epithelial alveolar barrier, most likely the ovine mammary epithelial cells (OMEC) of the acini. In situ hybridization confirmed these findings. Ultrastructural studies showed the presence of lentivirus-like particles budding off the cell surface in the alveolar barrier and also free in the acinar lumen. The presence of mammary histopathological lesions and MVV together with clear indications of productive infection (demonstration of a cytopathic effect in OMEC cultures and infection of co-cultures) were observed in the 15 seropositive and one of the seronegative sheep from the infected flock. These findings demonstrate that the OMEC were infected in vivo and probably underwent productive infection when studied ex-vivo. The OMEC of MVV-free sheep, which had subsequently been infected in vitro with MVV, also showed productive infection when challenged in vitro, confirming the replication of MVV in OMEC in vitro. The presence of MVV-infected OMEC in the mammary gland from infected animals, the productive infection in these OMEC and the release of lentiviral particles to the acinar lumen may have relevance in the pathogenesis and transmission of MVV infection. maedi-visna / mammary gland / epithelial cells / indurative mastitis / ovine

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Ovine lentivirus induced indurative lymphocytic mastitis and its effect on the growth of lambs

Cited by 43 publications

References 0 publications

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

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

The effect of footrot on weight gain in sheep

Maedi-visna virus infection of ovine mammary epithelial cells

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