A request for sheep with testicular feminization

Extract

Sir,—I should like to make a request to interested veterinarians for live specimens of the rare condition in sheep — testicular feminization.     

新孢子虫荧光PCR检测方法的研究

根据已知的犬新孢子虫种属特异性基因片段Nc-5基因序列,设计荧光定量PCR引物和荧光探针,经反应条件的优化,建立了检测新孢子虫的荧光定量PCR方法。该方法的检测灵敏度为10拷贝/反应。通过对系列稀释的重组质粒进行重复性检测,Ct值的变异系数为0.50%~1.18%。应用该方法对50份牛全血和8份流产胎儿样本进行检测,有5份全血和1份流产胎儿样本为阳性,阳性检出率均为10.3%,比普通PCR方法阳性检出率（7%）高。且具有较好的特异性和可重复性,可用来对新孢子虫病快速准确检测。     

Oxidative stress in dairy cows seropositives for Neospora caninum

Bovine neosporosis is caused by the protozoan Neospora caninum and is one of the major causes of abortion in cows. Cattle are intermediate hosts of this parasite and may have asymptomatic or symptomatic infections. Therefore, the aim of this study was to evaluate oxidative stress marker reactive oxygen species (ROS), thiobarbituric reactive acid substances (TBARS) levels, glutathione S-transferase (GST), adenosine deaminase (ADA), and butyrylcholinesterase (BChE) activities in dairy cows seropositives for N. caninum (asymptomatic or symptomatic). Dairy cows (n = 90) were tested by immunofluorescent antibody assay (IFA) for N. caninum and divided accordingly into three groups: the group A (seronegatives, n = 30), the group B (seropositives and asymptomatic, n = 30), and the group C (seropositives and symptomatic, n = 30). It was observed increased levels of TBARS and reduced (P < 0.05) BChE activity in seropositives either asymptomatic or symptomatic animals. ROS levels and ADA activity increased, and GST activity decreased (P < 0.05) only in seropositives symptomatic dairy cows (the group C) compared to seronegatives dairy cows (the group A). Based on these results, it was observed that seropositive animals showed cell damage associated with oxidative stress and inflammation, mainly in those with symptomatic infections. Increased seric ROS levels and BChE activity may have influenced N. caninum pathogenesis in symptomatic animals due to increased cell damage and exacerbated inflammatory response, leading to the development of clinical signs.     

Search for Neospora caninum DNA in bull semen using PCR

Neospora caninum represents one of the most frequent abortifaciant organisms worldwide. The parasite is diaplacentally transmitted from the pregnant cow to the fetus, where it normally leads to the delivery of a healthy, however persistently infected calf. Abortion thus is a relative rare event. The transmission of bovine neosporosis occurs in more than 90% of the cases vertically due to the endogenous reactivation of a persistently infected mother. Exogenous infections are therefore responsible for less than 10% of the cases.The question arises about which infection sources may be relevant in this context. In Switzerland, the role of dogs as definitive hosts has been shown to be of low significance in that respect. Recently, discussion focused on the potential of infectious bull semen following natural or artificial insemination. Thus, a few years ago a report documented the detectability of N. caninum-DNA in the semen of naturally infected bulls by nested-PCR. As a consequence, we decided to gain own experience by investigating 5 separate semen specimens per animal, originating from 20 N. caninum-seropositive bulls used for artificial insemination in Switzerland. All probes turned out to be negative by nested PCR. Based upon our laboratory experiences, the potential bull semen-associated Neospora-problem seems not to affect the Swiss bull population, thus there is no evidence to include further respective means of control.     

新孢子虫二温式PCR检测方法的建立及应用

根据新孢子虫Nc2基因保守区设计特异性引物,应用均匀设计法优化反应中Taq DNA聚合酶、引物浓度和退火温度等,建立新孢子虫二温式PCR检测方法。结果显示,扩增条带与预期目的片段大小(266bp)相符,未扩增出弓形虫等虫种的阳性DNA片段;扩增片段经克隆、测序发现与引物基因序列的同源性为100%;最低检出量为32.5fg/μL,是三步法PCR的10-1倍,但循环时间缩短了38min;重复3次对10-4、10-5、10-6和10-7稀释的阳性质粒进行二温扩增,10-7稀释均未出现扩增条带。同时对156份牛全血DNA进行检测,检出率为10.90%(17/156),与《新孢子虫病检疫技术规范》(SN/T 3499—2013)的检出符合率为83.33%(30/36),二者检测结果差异性不显著(P0.05)。由此可见,建立的二温式PCR检测方法可用于临床诊断和日常监测新孢子虫,为监控"带虫宿主"提供技术支撑。     

Neospora abortion in New Zealand cattle

Protozoal abortion in cattle was retrospectively studied by examining material submitted to the Batchelar Animal Health Laboratory in the years 1987-90. Only cases in which foetal brain had been submitted were examined. Histologically, protozoal lesions were seen in the brains of 28% of 320 aborted foetuses. Lesions were also seen in 10% of the hearts and 34% of the placentas examined, but these were not as characteristic as those in the brains. Protozoa, confirmed immunohistochemically as being Neospora caninum-like in two brains, were seen in 5% of aborted foetuses with lesions. No protozoa or associated lesions were seen in 57 late term foetuses or neonatal controls. A farm survey supported the hypothesis that Neospora is an important cause of multiple abortions in cattle. Laboratory and farm data suggested that protozoal abortion was more common in early gestation. No predisposing causes of abortion were found and there was no evidence of point infection of affected herds.     

Neospora caninum detected in feral rodents

The role of rodents in the epidemiology of neosporosis was investigated by assaying brain tissue of feral mice (Mus musculus) and rats (Rattus norvegicus) for Neospora caninum. Both mouse and rat brain tissue were extracted for total DNA, and subjected to two different N. caninum-specific nested polymerase chain reaction (PCR) assays. A portion of brain tissue from the mice and rats were also assayed for N. caninum in gerbils or gamma-interferon gene knockout (KO) mice. Of the 105 feral mice tested, 10% were positive in the N. caninum-specific PCR assays. Of the 242 rats tested, 30% were positive in both assays. Although mice and rats had N. caninum by PCR testing, clinical signs of N. caninum infection were not observed nor were N. caninum parasites observed in gerbils or KO mice inoculated with the rodent brain tissue.     

Vaccine development against Neospora caninum infection

Neospora caninum is a recognized protozoan parasite of a wide range of mammalian hosts, and was reported for the first time in 1988. The isolation of its oocysts in dog's faeces in 1998 led to its establishment as a parasitic species undergoing typical coccidian life cycle. Infection with N. caninum causes paralysis and death in young livestock and companion animals, and is associated with abortions and stillbirth in cattle, and neurologic disease in calves. Considering the economic and agricultural importance of neosporosis, there is the urgent need to develop biological control measures aimed at preventing its transmission, infection, as well as reducing severity of the disease. In this paper, we have reviewed the progress made to date on the parasite-host immunology and on vaccine development including its prospects, and discussed possible strategies in the formulation of vaccine(s) against neosporosis.     

Horner's syndrome associated with Neospora infection

A working collie cross was presented with a three-month history of vague neurological signs and a right-sided Horner's syndrome. Denervation hypersensitivity testing suggested a first order syndrome. There was a significant positive titre to Neospora and clinical signs resolved completely following treatment.