Effect of an inactivated bluetongue serotype 8 vaccine on semen quality in rams

The aim of this study was to determine whether a single dose of an inactivated bluetongue virus serotype 8 (BTV-8) vaccine altered semen quality in rams. Twenty sexually mature rams were assigned to three experimental groups: two groups of four animals were vaccinated and a third group of four animals was unvaccinated. The first group included rams with a history of natural BTV-8 infection in 2007 and the second and third groups included BTV-8 na?ve rams. Semen was collected prior to vaccination and for 4months post-vaccination. There were no significant differences in semen quality traits, including motility and concentration of spermatozoa, and percentages of living, normal dead and abnormal dead spermatozoa, between vaccinated and unvaccinated groups, or over time (P>0.05). The BTV-8 vaccine tested in this study did not appear to have any adverse effect on semen quality in rams.     

Viral RNA load in semen from bluetongue serotype 8-infected rams: relationship with sperm quality

This study investigated if viral RNA was detectable in the semen of rams clinically infected with bluetongue virus serotype 8 (BTV-8) by RT-qPCR, and to what extent the amount detected may be predictive of sperm quality. Semen samples were collected on six occasions from 93 BTV-8 infected rams involved in two longitudinal (n=12 and 27, respectively) and one cross-sectional (n=54) field study. Semen quality was assessed in terms of mass motility, concentration of spermatozoa, percentage of living and dead spermatozoa as well as cytological features. An overall semen quality score (SQS) was established. Depending upon the studied population, BTV RNA was detected in 75-100% of semen samples at initial testing 25-57 days post-observation (DPO) of clinical signs, and was detectable up to 116 DPO in a proportion of rams undergoing repeated sampling. Semen quality variables were significantly altered following natural BTV-8 infection and correlated with the amount of BTV RNA present. The SQS did not return to normal when virus was no longer detectable, suggesting that clearance of BTV precedes full recovery of sperm quality. In conclusion, viral RNA may be transiently recovered from the semen of BTV-8 affected rams and may serve as an indicator in predicting ram breeding potential following natural infection.     

Bovine infection with bluetongue virus with special emphasis on European serotype 8

Bluetongue virus (BTV) is an arthropod-borne virus infecting domestic and wild ruminants. Infection in cattle is commonly asymptomatic and characterised by a long viraemia. Associated with the emergence and the recrudescence of BTV serotype 8 (BTV-8) in Northern and Central Europe, remarkable differences have been noticed in the transmission and in the clinical expression of the disease, with cattle showing clinical illness and reproductive disorders such as abortion, stillbirth and fetal abnormalities. Several investigations have already indicated the putative ability of the European BTV-8 strain to cross the bovine placenta and to cause congenital infections. The current epidemiological and pathological findings present an unusual picture of the disease in affected bovines.     

Transplacental and oral transmission of wild-type bluetongue virus serotype 8 in cattle after experimental infection

Potential vertical transmission of wild-type bluetongue virus serotype 8 (BTV-8) in cattle was explored in this experiment. We demonstrated transplacental transmission of wild-type BTV-8 in one calf and oral infection with BTV-8 in another calf. Following the experimental BTV-8 infection of seven out of fifteen multi-parous cows eight months in gestation, each newborn calf was tested prior to colostrum intake for transplacental transmission of BTV by RRT-PCR. If transplacental transmission was not established the calves were fed colostrum from infected dams or colostrum from non-infected dams spiked with BTV-8 containing blood. One calf from an infected dam was born RRT-PCR positive and BTV-specific antibody (Abs) negative, BTV was isolated from its blood. It was born with clinical signs resembling bluetongue and lived for two days. Its post-mortem tissue suspensions were RRT-PCR positive. Of the seven calves fed colostrum from infected dams, none became infected. Of the six calves fed colostrum from non-infected dams spiked with infected blood, one calf became PCR-positive at day 8 post-partum (dpp), seroconverted 27 days later, and remained RRT-PCR and Abs positive for the duration of the experiment (i.e., 70 dpp). This work demonstrates that transplacental transmission in late gestation and oral infection of the neonate with wild-type BTV-8 is possible in cattle under experimental conditions.     

Molecular epidemiology of bluetongue virus serotype 1 isolated in 2006 from Algeria

This study reports on an outbreak of disease that occurred in central Algeria during July 2006. Sheep in the affected area presented clinical signs typical of bluetongue (BT) disease. A total of 5245 sheep in the affected region were considered to be susceptible, with 263 cases and thirty-six deaths. Bluetongue virus (BTV) serotype 1 was isolated and identified as the causative agent. Segments 2, 7 and 10 of this virus were sequenced and compared with other isolates from Morocco, Italy, Portugal and France showing that they all belong to a ‘western’ BTV group/topotype and collectively represent a western Mediterranean lineage of BTV-1.     

The length of BTV-8 viraemia in cattle according to infection doses and diagnostic techniques

Four groups of BTV free Frisian and cross bred calves were used to determine the length of viraemia following infection with different doses of BTV-8 Italian isolate. The first group of five animals was infected with 10 TCID₅₀ of BTV-8, the second group of four animals with 10³ TCID₅₀ and the third group, which also included four animals, was infected with 10⁶ TCID₅₀. A placebo containing uninfected tissue culture medium was given to the four animals of the fourth group. The viraemia was evaluated by real time RT-PCR and virus isolation. In all infected groups, virus isolation was able to detect infectious virus up to 39 days post infection (dpi) while RT-PCR was positive up to 151–157 dpi. Infectious dose did influence neither the length nor the pattern of BTV-8 viraemia and confirmed that real time RT-PCR remains positive although no circulating virus is detectable in the peripheral circulation.     

Impact of human interventions on the spread of bluetongue virus serotype 8 during the 2006 epidemic in north-western Europe

Bluetongue virus (BTV) can be spread by movement or migration of infected ruminants. Infected midges (Culicoides sp.) can be dispersed with livestock or on the wind. Transmissions of infection from host to host by semen and trans-placental infection of the embryo from the dam have been found. As for any infectious animal disease, the spread of BTV can be heavily influenced by human interventions preventing or facilitating the transmission pathways. This paper describes the results of investigations that were conducted on the potential role of the above-mentioned human interventions on the spread of BTV-8 during the 2006 epidemic in north-western Europe. Data on surveillance and control measures implemented in the affected European Union (EU) Member States (MS) were extracted from the legislation and procedures adopted by the national authorities in Belgium, France, Germany, and The Netherlands. The impact of the control measures on the BTV-incidence in time and space was explored. Data on ruminant transports leaving the area of first infection (AFI) to other areas within and beyond the affected MS were obtained from the national identification and registration systems of the three initially affected MS (Belgium, Germany, The Netherlands) and from the Trade Control and Expert System (TRACES) of the European Commission. The association between the cumulative number of cases that occurred in a municipality outside the AFI and the number of movements or the number of animals moved from the AFI to that municipality was assessed using a linear negative binomial regression model. The results of this study indicated that the control measures which were implemented in the affected MS (in accordance with EU directives) were not able to fully stop further spread of BTV and to control the epidemic. This finding is not surprising because BT is a vector-borne disease and it is difficult to limit vector movements. We could not assess the consequences of not taking control measures at all but it is possible, if not most likely, that this would have resulted in even wider spread. The study also showed an indication of the possible involvement of animal movements in the spread of BTV during the epidemic. Therefore, the prevention of animal movements remains an important tool to control BTV outbreaks. The extension of the epidemic to the east cannot be explained by the movement of animals, which mainly occurred in a north-western direction. This indicates that it is important to consider other influential factors such as dispersal of infected vectors depending on wind direction, or local spread.     

The 2006 outbreak of bluetongue in northern Europe—The entomological perspective

After bluetongue (BT) appeared in northern Europe in August 2006 entomological studies were implemented in all five affected Member States (MSs) to establish which species of Culicoides had acted as vectors. The findings can be summarised as follows: (i) C. imicola the principal southern European/African vector of BTV has not penetrated into northern Europe, (ii) three pools of C. obsoletus/C. scoticus and one of C. dewulfi assayed RT-PCR-positive to BTV-8, (iii) in support of these results it was found that both potential vectors had also high parity rates (approximately 40%) indicating increased longevity favouring BTV virogenesis and transmission, (iv) furthermore, C. obsoletus/C. scoticus and C. dewulfi occurred also widely and abundantly on sheep and cattle holdings across the entire affected region, (v) and during the latter part of the season showed strong endophily readily entering livestock buildings in significant numbers to bite the animals inside (endophagy), (vi) which demonstrates that housing at best offers only limited protection to livestock from Culicoides attacks, (vii) in contrast the potential vector C. pulicaris sensu stricto was restricted geographically, was captured rarely, had a low parity rate (10%) and was exophilic indicating it played no role in the outbreak of BT, (viii) the incrimination of C. dewulfi as a novel vector is significant because it breeds in cattle and horse dung this close association raising its vectorial potential, but (ix) problems with its taxonomy (and that of the Obsoletus and Pulicaris species complexes) illustrates the need for morphological and molecular techniques to become more fully integrated to ensure progress in the accurate identification of vector Culicoides, (x) midge densities (as adjudged by light traps) were generally low indicating northern European Culicoides to have a high vector potential and/or that significant numbers of midges are going undetected because they are biting (and transmitting BTV) during the day when light traps are not effective, and (xi) the sporadic capture of Culicoides in the winter of 2007 invites re-examination of the current definition of a vector-free period. The re-emergence of BT over a wide front in 2007 raises anew questions as to precisely how the virus overwinters and asks also that we scrutinise our monitoring systems in terms of their sensitivity and early warning capability.     

日粮锌水平对辽宁绒山羊种公羊精液品质的影响

为探讨日粮锌水平对辽宁绒山羊种公羊精液品质的影响。本试验选用成年健康、精液品质相近的辽宁绒山羊种公羊20只,随机分为4组,对照组饲喂基础饲粮,试验组分别在基础饲粮中添加20、40和80mg/kg的锌。结果表明:①日粮锌水平对种公羊的精液量、精子密度、精子活力和精子解冻后活力影响显著(P<0.05);②日粮锌水平对种公羊的精液pH值、美蓝褪色时间没有显著影响(P<0.05);③日粮锌水平对种公羊的降低鲜精和冻精畸形率有一定的促进作用(P>0.05)。综合鲜精、冻精品质指标,本试验日粮条件下,日粮锌添加量为40mg/kg辽宁绒山羊种公羊的精液品质最优。     

Possible routes of introduction of bluetongue virus serotype 8 into the epicentre of the 2006 epidemic in north-western Europe

In August 2006, bluetongue (BT) was notified in The Netherlands on several animal holdings. This was the onset of a rapidly spreading BT-epidemic in north-western Europe (latitude >51 degrees N) that affected cattle and sheep holdings in The Netherlands, Belgium, Germany, France and Luxembourg. The outbreaks were caused by bluetongue virus (BTV) serotype 8, which had not been identified in the European Union before. Bluetongue virus can be introduced into a free area by movement of infected ruminants, infected midges or by infected semen and embryos. In this study, information on animal movements or transfer of ruminant germ plasms (semen and embryos) into the Area of First Infection (AFI), which occurred before and during the onset of the epidemic, were investigated in order to establish the conditions for the introduction of this virus. All inbound transfers of domestic or wild ruminants, non-susceptible mammal species and ruminant germ plasms into the AFI during the high-risk period (HRP), registered by the Trade Control and Expert System (TRACES) of the EC, were obtained. Imports originating from countries with a known or suspected history of BTV-incidence of any serotype were identified. The list of countries with a reported history of BTV incidence was obtained from the OIE Handistatus II for the period from 1996 until 2004. No ruminants were imported from a Member State (MS) with a known history of BTV-8 or from any other country with a known or suspected history of BTV incidence of any serotype. Of all non-susceptible mammal species only 233 horses were transported directly into the AFI during the HRP. No importations of semen or embryos into the AFI were registered in TRACES during the period of interest. An obvious source for the introduction of BTV-8, such as import of infected ruminants, could not be identified and the exact origin and route of the introduction of BTV-8 thus far remains unknown. However, the absence of legal import of ruminants from outside the EU into the AFI and the absence of BTV-8 in southern Europe suggest that, the introduction of the BTV-8 infection into the north-western part of Europe took place via another route. Specifically, in relation to this, the potential for Culicoides to be imported along with or independently of the import of animals, plants or other 'materials', and the effectiveness of measures to reduce such a possibility, merit further study.     

Toggenburg Orbivirus, a new bluetongue virus: Initial detection, first observations in field and experimental infection of goats and sheep

A novel bluetongue virus termed “Toggenburg Orbivirus” (TOV) was detected in two Swiss goat flocks. This orbivirus was characterized by sequencing of 7 of its 10 viral genome segments. The sequencing data revealed that this virus is likely to represent a new serotype of bluetongue virus [Hofmann, M.A., Renzullo, S., Mader, M., Chaignat, V., Worwa, G., Thuer, B., 2008b. Genetic characterization of Toggenburg Orbivirus (TOV) as a tentative 25th serotype of bluetongue virus, detected in goats from Switzerland. Emerg. Infect. Dis. 14, 1855–1861].In the field, no clinical signs were observed in TOV-infected adult goats; however, several stillborn and weak born kids were reported. Although born during a period of extremely low vector activity, one of these kids was found to be antibody and viral genome positive and died 3.5 weeks postpartum.Experimental infection of goats and sheep, using TOV-positive field blood samples, was performed to assess the pathogenicity of this virus.Goats did not show any clinical or pathological signs, whereas in sheep mild bluetongue-like clinical signs were observed. Necropsy of sheep demonstrated bluetongue-typical hemorrhages in the wall of the pulmonary artery. Viral RNA was detected in organs, e.g. spleen, palatine tonsils, lung and several lymph nodes of three experimentally infected animals.Unlike other bluetongue virus serotypes, it was not possible to propagate the virus, either from naturally or experimentally infected animals in any of the tested mammalian or insect cell lines or in embryonated chicken eggs.In small ruminants, TOV leads to mild bluetongue-like symptoms. Further investigations about prevalence of this virus are needed to increase the knowledge on its epidemiology.     

绵羊精液稀释液中添加PUFA对冷冻精液品质的影响

通过在绵羊精液冷冻稀释液葡3-3稀释液(葡萄糖-柠檬酸盐-卵黄)中添加富含多不饱和脂肪酸(PUFA)的深海鱼油,研究其对绵羊精子冷冻-解冻过程的作用.     

Effects on boar semen quality after infection with porcine reproductive and respiratory syndrome virus: a case report

The effect of porcine reproductive and respiratory syndrome virus (PRRSV) on semen quality was examined in a group of 11 spontaneously infected boars in a commercial boar stud. Semen samples were collected 4 weeks prior to 4 weeks post-infection (wpi). Infection with PRRSV of the European genotype subtype 1 (EU-1) was verified by specific quantitative real-time polymerase chain reaction (RT-PCR) in 36% of the serum samples. All boars seroconverted before 4 wpi and remained in normal condition throughout the study. Comparison of the percentage of morphologically intact spermatozoa revealed an increase of acrosome-defective spermatozoa (P = 0.012) between −4 and 4 wpi. Significant deleterious effects on semen quality were detected for membrane integrity when semen had been stored for 2 days after sampling. Analysis of sperm subpopulations in a thermoresistance test on day 7 after sampling revealed alterations in the percentage of circular, progressively motile spermatozoa (P = 0.013), in the percentage of non-linear, progressively motile spermatozoa (P = 0.01), and on the amplitude of lateral sperm head displacement (P = 0.047). There was no difference in the incidence of mitochondrially active spermatozoa (P = 0.075). Investigation of routine production data between pre- and post-infection status showed no differences on ejaculate volume (P = 0.417), sperm concentration (P = 0.788), and percentage of motile spermatozoa (P = 0.321). This case report provides insights into a potential control strategy for PRRSV outbreaks in boar studs.     

Simulation analysis of the effect of herd immunity and age structure on infection of a cattle herd with bluetongue viruses in Queensland, Australia

A state-transition model based on Leslie matrix formulation was used to investigate the effects of herd immunity and age structure on the infection of a simulated cattle herd with bluetongue viruses under Australian climatic conditions. Increasing duration of immunity decreased the prevalence of infection. A duration of immunity of 33 months was consistent with prevalence estimates made from previous serological studies of bluetongue virus. Herd prevalence displayed slowly dampening cyclical variation over time (most pronounced when a short duration of immunity was simulated). Increasing calving and mortality risk rates in the simulated herd increased prevalence, whereas increasing age at first calving decreased prevalence. Manipulation of calving rates had the greatest effect on the predicted prevalence of infection in the herd. Simulation of a number of herd-management scenarios suggested that management systems in which cattle are bred early and where high calving rates are achieved are likely to contribute to high levels of infection with bluetongue viruses. Results confirm the importance of management factors in influencing the prevalence of infectious diseases in animal populations.     

Dynamics of natural bovine herpesvirus-1 (BoHV-1) infection in a dairy herd

In this study, natural cycling of BoHV-1 infection was investigated in two groups of dairy cattle containing 2120 head. Group 1 comprised 127 animals and they were monitored for BoHV-1 infection virologically and serologically in six consecutive sampling periods. It consisted of naive heifers between 6 and 8 months of age, while in group 2, age, sex and the BoHV-1 serostatus of the animals were disregarded. The animals in group 1 were found to have seroconverted at the second sampling. Results of the serological study showed slight antibody response after natural BoHV-1 infection in the herd and neutralizing titres fell below protective levels in the 6–8 months after the peak. During the 2-year study period, one recurrence was detected after primary infection. Virus isolation studies revealed a cytopathic effect indicative of BoHV-1 in two nasal swabs taken during the fifth sampling period from animals with mild upper respiratory tract symptoms. As the study was carried out under natural conditions, it is not known whether the viruses isolated were from recurrences or re-infections. Data from cross-neutralization tests with herd isolates showed higher antibody response than those with the reference virus. The dynamics of BoHV-1 in both groups were found to be statistically similar.     

Field observations during the bluetongue serotype 8 epidemic in 2006. I. Detection of first outbreaks and clinical signs in sheep and cattle in Belgium, France and the Netherlands

Starting August 2006, a major epidemic of bluetongue (BT) was identified in North-West Europe, affecting The Netherlands, Belgium, Germany, Luxemburg and the North of France. It was caused by BT virus serotype 8 (BTV-8), a serotype previously unknown to the European Union (EU). In this outbreak, the virus caused clinical disease in a few individual animals within cattle herds, whereas overt clinical disease was usually restricted to sheep. Investigations in Belgium suggested that the first clinical signs of BTV-8 appeared mid July 2006 in a cattle herd, while the first suspicion of a BT-outbreak in Belgium was reported on 17 August 2006. In the first 10 BTV-8 outbreaks in the Netherlands, the owners indicated that the first clinical signs started approximately 12-17 days before a suspicion was reported to the veterinary authorities via a veterinary practitioner. In BTV-8 affected sheep flocks, erosions of the oral mucosa, fever, salivation, facial and mandibular oedema, apathy and tiredness, mortality, oedema of the lips, lameness, and dysphagia were among the most frequent clinical signs recorded. The most prominent clinical signs in BTV-8 affected cattle herds were: crusts/lesions of the nasal mucosa, erosions of lips/crusts in or around the nostrils, erosions of the oral mucosa, salivation, fever, conjunctivitis, coronitis, muscle necrosis, and stiffness of the limbs. Crusts/lesions of nasal mucosa, conjunctivitis, hyperaemic/purple coloration and lesions of the teats, and redness/hypersensitivity of the skin were relatively more seen on outbreak farms with cattle compared to sheep. Mortality, oedema of the head and ears, coronitis, redness of the oral mucosa, erosions/ulceration of tongue mucosa, purple coloration of the tongue and tongue protrusion and dyspneu were relatively more seen on outbreak farms with sheep compared to cattle.     

Staphylococcus aureus intra-mammary infection affects the expression pattern of IL-R8 in goat

IL-1R8 is a member of Interleukin-1 receptor family acting as a negative regulator of inflammation reliant on ILRs and TLRs activation. IL-1R8 role has never been evaluated in acute bacterial mastitis. We first investigated IL-1R8 sequence conservation among different species and its pattern of expression in a wide panel of organs from healthy goats. Then, modulation of IL-1R8 during natural and experimental mammary infection was evaluated and compared in blood, milk and mammary tissues from healthy and Staphylococcus aureus infected goats. IL-1R8 has a highly conserved sequence among vertebrates. Goat IL-1R8 was ubiquitously expressed in epithelial and lymphoid tissues with highest levels in pancreas. IL-1R8 was down-regulated in epithelial mammary cells following S. aureus infection. Interestingly it was up-regulated in leukocytes infiltrating the infected mammary tissues suggesting that it could represent a target of S. aureus immune evasion.     

Effect of semen collection frequency on seasonal variation in sexual behaviour,testosterone, testicular size and semen characteristics of tropical hair rams (<Emphasis Type="Italic">Ovis aries</Emphasis>)

The purpose of this study was to examine the effect of day length on seminal characteristics, testicular size, sexual behaviour and testosterone (T4) concentration in Pelibuey rams subjected to different semen collection frequencies. Eighteen intact males were assigned randomly to one of two semen collection frequencies: in the high rate (HR) treatment, two ejaculations per week were obtained from each ram; one ejaculation every two weeks was collected under the low rate (LR) treatment. All animals were housed individually in contiguous 5 m × 5 m wire mesh pens and evaluated over a 12-month period. At the beginning of the experiment rams were 20 months old and 40–50 kg in weight. All rams ejaculated and produced semen throughout the year. Semen volume, sperm per ejaculation, testicular circumference and testicular volume were significantly (p < 0.05) greater during short days in all rams, regardless of the semen collection frequency, with the exception of sperm concentration, for which no variation was found in HR individuals, and reaction time and T₄ levels, for which no variation was found in LR males. Rams subjected to HR collection were more affected by the short-day photoperiod than rams collected twice per week, exhibiting greater reduction (p < 0.05) in time to achieve their first ejaculation and in sperm per ejaculation, as well as greater increases (p < 0.05) in T₄ concentration than LR rams (14.65 ± 1.22 vs 23.53 ± 5.34 s, (3.37 ± 0.17) × 10⁹ vs (3.52 ± 0.20) × 10⁹ sperm and 8.68 ± 0.44 vs 6.85 ± 0.74 ng/ml, respectively). It was concluded that: (a) the magnitude of the seasonal effects was not sufficient to prevent the rams being used for breeding throughout the year, and (b) seasonal variation within variables was affected differently between semen collection frequencies.