Seroepidemiology of bluetongue disease in small ruminants of northeast of Iran

Objective:To estimate the prevalence and distribution of bluetongue vims antibody in sheep and goats in 25 townships of Khorasan Razavi.Bluetongue is an infectious,non-contagious,arthropod born viral disease of ruminants and has been reported from most of the tropical and subtropical regions of the world.Methods:A total number of 1034 serum samples from sheep and goats were collected and transmitted to Serological Laboratory of Veterinary Council of Khorasan Razavi.Serums were screened for the presence of group-specific bluetongue virus antibody using competitive Enzyme Linked Immuno Sorbent Assay(c-ELISA).Kesults:The seropositivitv of sheep and goats for bluetongue was found to be 89.2%.The highest prevalence rate was seen in Taybad.Khalil-abad and Torbat-jam(100%)and the least prevalence rate was seen in Jovein(55%).Conclusions:The results showed that the majority of animals in the north-east of Iran are infected with bluetongue vims.High correlation between abortion history and seroposivity emphasize the economical importance of bluetongue virus in the sheep herds of the region.

ISG20 inhibits bluetongue virus replication

ISG20 is an interferon-inducible exonuclease that inhibits virus replication.Although ISG20 is thought to degrade viral RNA,the antiviral mechanism and specificity of ISG20 remain unclear.In this study,the antiviral role of ovine ISG20(o ISG20)in bluetongue virus(BTV)infection was investigated.It was found that BTV infection upregulated the transcription of ovine ISG20(o ISG20)in a time-and BTV multiplicity of infection(MOI)-dependent manner.Overexpression of o ISG20 suppressed the production of BTV genome,proteins,and virus titer,whereas the knockdown of o ISG20 increased viral replication.o ISG20 was found to co-localize with BTV proteins VP4,VP5,VP6,and NS2,but only directly interacted with VP4.Exonuclease defective o ISG20 significantly decreased the inhibitory effect on BTV replication.In addition,the interaction of mutant o ISG20 and VP4 was weakened,suggesting that binding to VP4 was associated with the inhibition of BTV replication.The present data characterized the anti-BTV effect of o ISG20,and provides a novel clue for further exploring the inhibition mechanism of double-stranded RNA virus by ISG20.

蓝舌病病毒一步RT-PCR检测方法的建立

为建立蓝舌病病毒（BTV）群特异性核酸检测方法,本研究针对BTV S10基因保守区域设计并合成1对特异性引物,建立了一步RT-PCR检测方法,并分别进行了特异性试验、敏感性试验以及临床样品的检测.实验结果表明：该方法对BTV1～24型均有特异性反应,而对茨城病毒（IBAV）、中山病毒（CV）和赤羽病病毒（AKAV）无交叉反应,具有良好的特异性;最低检出量为102 TCID50/mL.此外,该方法能有效的从羊的抗凝血样品中检测出BTV核酸.本研究所建立的一步RT-PCR检测方法可以用于BTV的快速检测及流行病学调查.

Importance of Viral Disease in Dairy Cow Fertility

Many viral diseases are endemic in cattle populations worldwide. The ability of many viruses to cross the placenta and cause abortions and fetal malformations is well understood. There is also significant evidence that viral infections have additional actions in dairy cows, which are reflected in reduced conception rates. These effects are, however, highly dependent on the time at which an individual animal first contracts the disease and are less easy to quantify. This paper reviews the evidence relating to five viruses that can affect fertility, together with their potential mechanisms of action. Acute infection with non-cytopathic bovine viral diarrhea virus (BVDV) in mid-gestation increases abortion rates or causes the birth of persistently infected calves. BVDV infections closer to the time of breeding can have direct effects on the ovaries and uterine endometrium, which cause estrous cycle irregularities and early embryo mortality. Fertility may also be reduced by BVDV-induced immunosuppression, which increases the susceptibility to bacterial infections. Bovine herpesvirus (BHV)-1 is most common in pre-pubertal heifers, and can slow their growth, delay breeding, and increase the age at first calving. Previously infected animals subsequently show reduced fertility. Although this may be associated with lung damage, ovarian lesions have also been reported. Both BHV-1 and BHV-4 remain latent in the host following initial infection and may be reactivated later by stress, for example associated with calving and early lactation. While BHV-4 infection alone may not reduce fertility, it appears to act as a co-factor with established bacterial pathogens such as Escherichia coli and Trueperella pyogenes to promote the development of endometritis and delay uterine repair mechanisms after calving. Both Schmallenberg virus (SBV) and bluetongue virus (BTV) are transmitted by insect vectors and lead to increased abortion rates and congenital malformations.BTV-8 also impairs the development of hatched blastocysts;furthermore, infection around the time of breeding with either virus appears to reduce conception rates. Although the reductions in conception rates are often difficult to quantify, they are nevertheless sufficient to cause economic losses, which help to justify the benefits of vaccination and eradication schemes.

Detection of arboviruses in Culicoides(Diptera:Ceratopogonidae)collected from animal farms in the border areas of Yunnan Province,China

Biting midges of the genus Culicoides(order Diptera,family Ceratopogonidae)are potential biological vectors for the transmission of certain arboviruses among humans,livestock,and wild animals.This study collected a total of 405 Culicoides individuals from seven animal farms located in five counties in the border areas of Yunnan Province,China,and examined the Culicoides species composition and the major arboviruses carried by the Culicoides species.The collected Culicoides were classified into seven species with variable abundances:Culicoides arakawae(5.43%,22/405),Culicoides homotomus(1.23%,5/405),Culicoides obsoletus(19.75%,80/405),Culicoides orientalis(17.28%,70/405),Culicoides oxystoma(29.38%,119/405),Culicoides peregrinus(5.68%,23/405),and Culicoides nipponensis(21.23%,86/405).Among the seven species,C.oxystoma and C.nipponensis were distributed in all the five counties with abundances of 13.33–44.87%and 10.00–46.83%,respectively,suggesting that these were the dominant species of Culicoides widespread on animal farms in the border areas.PCR was used to detect major arboviruses in the collected Culicoides specimens,including bluetongue virus(BTV),Japanese encephalitis virus,Dengue virus,Zika virus,African swine fever virus,and African horse sickness virus.Among the tested viruses,only BTV serotype 1 was tested positive in C.oxystoma specimens collected from a buffalo farm.Culicoides oxystoma was the dominant species on animal farms in the sampled areas,but it has not previously been documented as positive for BTV in China.The current results thus suggest that C.oxystoma could be an important vector for BTV transmission in these border areas,which,however,needs to be confirmed by further comprehensive experiments.Overall,the present study provides the first profile of Culicoides species on animal farms in the China,Vietnam,and Myanmar border areas,establishes the prevalence of arboviruses carried by these Culicoides species,and suggests the vector potential of C.oxystoma species for the transmission of BTV.