Analysis of the risk of introduction and spread of porcine reproductive and respiratory syndrome virus through importation of raw pigmeat into New Zealand

AIMS: To determine the frequency with which porcine reproductive and respiratory syndrome (PRRS) virus (PRRSv) would become established in a non-commercial pig herd in New Zealand due to illegal feeding of uncooked food waste containing virus-contaminated pigmeat. To determine the likelihood of a single incursion resulting in a multi-farm outbreak of the disease, and describe the spatio-temporal characteristics of such an outbreak.

METHODS: A Monte Carlo simulation model was constructed to determine the expected annual frequency of PRRSv infection being initiated in a non-commercial pig herd as a result of inadvertent feeding of pigmeat imported from countries endemically infected with the disease. Once the likelihood of PRRSv becoming established in a single pig herd was determined, stochastic spatially explicit infectious disease modelling software was utilised to model the temporal and spatial characteristics of the resulting epidemic.

RESULTS: Assuming the proportion of imported pigmeat remained at current levels, consumption patterns of pigmeat in households in New Zealand remained steady, and limited compliance with recently reintroduced regulations to prevent feeding of uncooked food waste, at least 4.3 pig herds per year were predicted to become infected with PRRSv. Simulation modelling of PRRSv epidemics related to initial infection of a non-commercial farm produced an estimate that 36% of these incursions would spread from the initial herd, and that these outbreaks would involve 93 herds on average in the first year. By increasing the estimated persistence of PRRSv infection in small herds, an average of 205 herds became infected in the first year.

CONCLUSIONS: Given a mean of 4.3 infected premises per year and a 36% probability of infection spreading beyond the initial infected herd, there was a 95% likelihood of a multi-farm PRRS outbreak occurring within 3 years.

CLINICAL RELEVANCE: Introduction of PRRSv through importation of virus-contaminated pigmeat presents a high risk for establishment of the disease in the pig industry in New Zealand.     

Potential Proteomic-Based Strategies for Understanding Laminitis: Predictions and Pathogenesis

With today's understanding of the genome, advanced molecular techniques, and our growing ability to analyze complex biologic data, proteomics, the broad-based study of the repertoire of proteins expressed by cells or organisms, offers great promise for understanding the causes of complex diseases. Identifying and measuring novel protein biomarkers present in blood that predict the onset and resolution of laminitis would both aid clinical management of at-risk equine patients and shed light on underlying mechanisms with the intent of developing novel preventive strategies and therapeutic approaches. Identifying alterations in the profiles of proteins present in tissues of horses that develop laminitis or within in vitro model systems also can advance our understanding of this puzzling disease.     

杂交改良对撒坝猪肉品质的影响——肌肉食用品质及肌纤维特性分析

 研究选用24kg左右的去势撒坝猪及其约长撒三元杂交猪各7头，根据基因型分成两组, 按活重变化分为3个试验期 （前:20～35kg，中: 35～60kg和后期60～90kg），在同一试验期内饲喂同样的日粮进行饲养试验，当活重达90kg进行屠宰试验，研究杂交改良对云南省本地猪种撒坝猪肉品质和肌纤维特性的影响。撒坝猪通过杂交改良后，生长速度和瘦肉率显著提高，但其肉品质均有不同程度的下降。杂交后代肌肉水分显著地增加（P<0.01），相反，肌肉粗蛋白（P<0.05）、粗脂肪和肌内脂肪（P<0.01）显著地降低。杂交后代的系水率、保水率、肉色、嫩度等指标均有不同程度的下降（差异不显著P>0.05），然而，大理石纹、熟肉率、滋味、多汁性和汤味显著下降（P<0.05）。肌纤维直径和密度变化较为显著。杂交后显著地降低了腰肌、股二头肌和背最长肌肌纤维密度（P<0.001）；腰肌、股二头肌和背最长肌肌纤维密度分别降低了22.3%，22.8%和19.3%。肌纤维密度降低的主要原因是杂交后显著地增加了腰肌、股二头肌和背最长肌肌纤维直径（P<0.01）；腰肌、股二头肌和背最长肌肌纤维直径分别增加了22.5%，18.1%和18.9%。     

A rapid immunoperoxidase-based virus neutralization assay for salmonid alphavirus used for a serological survey in Northern Ireland

A modified virus neutralization (VN) assay was developed to replace an existing assay read on the presence or absence of virus-induced cytopathic effect (CPE). The modified assay used a monoclonal antibody to salmon pancreas disease virus as the first layer of an immunoperoxidase (IPX)-based immunostaining technique to detect viral growth. The IPX-based VN assay required only 3 days to perform, and the adoption of a 96-well microtitre format facilitated a high throughput of samples requiring small volumes of serum, cells and virus. When 352 sera from farmed salmon and 302 sera from farmed trout were tested by both the modified and the original CPE-based assays, overall correlations of 97.72 and 96.03% were, respectively, obtained (96.94% combined). When the modified assay was used to test 188 sera collected from wild salmonids in freshwater river systems in Northern Ireland, no positive results were recorded.     

Geographical distribution of salmonid alphavirus subtypes in marine farmed Atlantic salmon, Salmo salar L., in Scotland and Ireland

Sequence data from salmonid alphavirus (SAV) strains obtained from farmed marine Atlantic salmon, Salmo salar L. , over a 20-year period between 1991 and 2011 was reviewed to examine the geographical distribution of the genetically defined SAV subtypes in twelve regions across Ireland and Scotland. Of 160 different Atlantic salmon SAV strains examined, 62 belonged to subtype 1, 28 to subtype 2, 34 to subtype 4, 35 to subtype 5 and 1 to subtype 6. SAV subtypes 1, 4 and 6 were found in Ireland, while subtypes 1, 2, 4 and 5 were found in Scotland. In the majority of regions, there was a clear clustering of subtypes, with SAV subtype 1 being the dominant subtype in Ireland overall, as well as in Argyll and Bute in Scotland. SAV subtype 2 predominated in the Shetland and Orkney Islands. The emergence in Atlantic salmon of subtype 2 strains typically associated with sleeping disease in rainbow trout in Argyll and Bute, strongly suggesting transmission of infection between these species, was noted for the first time. SAV subtype 4 was the most common subtype found in the southern Western Isles, while SAV subtype 5 predominated in the northern Western Isles and north-west mainland Scotland. No single strain was dominant on sites in the western Highlands, with a number of sites in this region in particular having more than one subtype detected in different submissions. The significance of these results in relation to aspects of the epidemiology of infection, including transmission, biosecurity and wildlife reservoirs are discussed and knowledge gaps identified.     

Congenital hypothyroidism in Scottish Deerhound puppies

Two Scottish Deerhound puppies had clinical and pathological features consistent with the diagnosis of congenital non-goitrous hypothyroidism. They were from separate litters, but were the progeny of the same sire and dam. The puppies were smaller, had shorter limbs and shorter, broader heads than their littermates. They also had histories of weakness, difficulty in walking and somnolence. A characteristic radiographic feature was the absence of epiphyseal growth centres. Both had depressed serum thyroxine (T4) levels and one did not respond to exogenous thyroid stimulating hormone. On necropsy, the thyroid glands were small, the follicles varied in size and contained little or no colloid. The adenohypophysis contained many cells with markedly vacuolated cytoplasm. It is suggested that the clinicopathological pattern is the result of a primary thyroid abnormality. Possible mechanisms include either primary thyroid hypoplasia or an unresponsiveness to thyroid stimulating hormone.