Survival and immunization of raccoons after exposure to pseudorabies (Aujeszky's disease) virus gene-deleted vaccines

In a controlled experiment, 16 wild-trapped raccoons were exposed to 1 of 2 genetically modified live pseudorabies virus (PRV) vaccines used in swine. One vaccine had genes deleted for thymidine kinase (TK(-)) and glycoprotein G (gG(-)); the other had an additional deletion for glycoprotein E (gE(-)). These vaccines were administered orally and intranasally at four dose levels: 10(3), 10(4), 10(5), and 10(6) TCID(50). The 21 days survival rate was 37.5% for the gG(-)TK(-) vaccine; all of the survivors developed antibodies to PRV. All animals receiving the gG(-)gE(-)TK(-) vaccine survived; 75% (all except the lowest dose) developed anti-PRV antibodies. Survivors were challenged intranasally with a 3.2x10(3) TCID(50) dose of the virulent wildtype PRV Shope strain. Two of the remaining three gG(-)TK(-) vaccinated raccoons survived the challenge; for the gG(-)gE(-)TK(-) vaccine, the survival rate was 50% (4/8). The raccoons with higher vaccine-induced antibody titers were more likely to survive the challenge with the virulent PRV; there was a 100% mortality rate for raccoons lacking detectable anti-PRV antibodies. This experiment indicates that exposure of raccoons to modified live gene-deleted PRV vaccines may result in an immune response, and that this immunity provides some protection against exposure to virulent virus.     

Study of the potential involvement of pseudorabies virus in swine respiratory disease.

In order to investigate the potential involvement of pseudorabies virus (PRV) in swine respiratory disease, nine week old pigs were intranasally inoculated with the PRV strain 4892. Two doses of infection were used: 10(4.5) median tissue culture infectious doses (TCID50)/pig and 10(3.5) TCID50/pig, with ten pigs per group. In the group of pigs inoculated with 10(4.5) TCID50, seven out of ten pigs died within six days after inoculation. The mortality rate in the group of pigs inoculated with the lower dose was only two out of ten and, there were several pigs in this group that showed signs of respiratory distress besides some mild nervous signs. Pseudorabies virus was isolated from various tissues collected postmortem, including alveolar macrophages. Virus localization in tissues was also detected by in situ hybridization. The histopathological examination of the respiratory tract tissues revealed a pathological process that was progressing from mild pneumonia to severe suppurative bronchopneumonia. The isolation of virus from alveolar macrophages provides support to the hypothesis that replication of PRV during the course of infection produces an impairment of the defense mechanisms in the respiratory tract.     

Specificity of the indirect enzyme-linked immunosorbent assay for detection of pseudorabies virus antibodies in pigs exposed to bovine herpesvirus-1

Six 5-week-old pigs were inoculated intranasally (IN) with 10(7.6) TCID50 of bovine herpesvirus-1 (BHV-1). Three of the pigs also were inoculated IV with a similar dose of BHV-1. Clinical responses were not observed in these 6 pigs before oronasal challenge exposure with 10(7.8) TCID50 of virulent pseudorabies virus (PRV) at postinoculation day 42. Two pigs inoculated IN with BHV-1 and challenge exposed with PRV remained healthy, whereas the remaining 4 pigs developed severe clinical signs of pseudorabies and were moribund at postinoculation day 50 (8 days after challenge exposure). Anti-BHV-1 antibodies were demonstrable by ELISA in all 6 pigs and by serum neutralization (SN) in 5 pigs before challenge exposure with PRV. Anti-PRV antibody was not detected by ELISA or SN before challenge exposure to PRV. After challenge exposure to PRV, pigs with humoral antibody to BHV-1 responded anamnestically, and anti-PRV antibody activity was demonstrable by ELISA and SN in the 2 surviving pigs.     

Evaluation in swine of a subunit vaccine against pseudorabies

A subunit vaccine against pseudorabies virus (PRV) was prepared by treating a mixture of pelleted virions and infected cells with the nonionic detergent Nonidet P-40 and emulsifying the extracted proteins incomplete Freund's adjuvant. Three 7-week-old pigs without antibodies against PRV were given 2 IM doses of this vaccine 3 weeks apart. Thirty days after the 2nd vaccination, 10(6) median tissue culture infective doses (TCID50) of a virulent strain of PRV were administered intranasally. Tonsillar and nasal swabs were collected daily between 2 and 10 days after challenge exposure. The pigs vaccinated with the subunit vaccine were not found to shed virulent PRV. Two groups of five 7-week-old pigs vaccinated with commercially available vaccines, either live-modified or inactivated virus, and subsequently exposed to 10(6) TCID50 of virulent PRV, shed virulent virus for up to 8 days. The subunit vaccine induced significantly higher virus-neutralizing antibody titers than either the live-modified or inactivated virus vaccine.     

Attenuated properties of thymidine kinase-negative deletion mutant of pseudorabies virus

A thymidine kinase (TK)-negative (TK-) deletion mutant of the Bucharest (BUK) strain of pseudorabies virus (PRV) was isolated. The mutant, designated as PRV (BUK d13), did not revert to TK-positive (TK+), even when propagated in medium that selected for TK+ viruses. The mutant also replicated equally well at 39.1 C and 34.5 C, and was easily distinguished from other PRV strains by molecular hybridization experiments, restriction nuclease fingerprints, and plaque autoradiography or other assays for the TK phenotype. The PRV (BUK d13) had greatly reduced virulence for mice and rabbits, compared with parental TK+ strains, PRV (BUK-5) and PRV (BUK-5A-R1), and provided mice with solid protection against the TK+ BUK and Aujeszky strains of PRV. Experiments were done in 5- to 6-week-old pigs to assess the safety and efficacy of PRV (BUK d13) in the natural host. In one experiment, pigs were vaccinated IM with 7.5 X 10(8) plaque-forming units of TK- PRV (BUK d13), and were then challenge exposed intranasally (IN) with 4.3 X 10(8) TCID50 of virulent PRV [Indiana-Funkhauser (IND-F)]. Vaccinated pigs did not have clinical signs of illness after vaccination or after challenge exposure. One nonvaccinated control pig died on postchallenge day 4; a 2nd nonvaccinated control pig became moribund, but eventually recovered. Pigs developed virus-neutralizing antibodies after vaccination, and had a secondary immunologic response after challenge exposure; however, PRV was not isolated from the tonsils or trigeminal ganglia of vaccinated pigs at postchallenge exposure day 11.(ABSTRACT TRUNCATED AT 250 WORDS)     

Efficacy of spray-drying to reduce infectivity of pseudorabies and porcine reproductive and respiratory syndrome (PRRS) viruses and seroconversion in pigs fed diets containing spray-dried animal plasma

Three experiments were conducted to evaluate viral inactivation by the spray-drying process used in the production of spray-dried animal plasma (SDAP). In Exp. 1, bovine plasma was inoculated with pseudorabies virus (PRV) grown in PK 15 cells. Three 4-L batches were spray-dried in the same manner and conditions of industrial SDAP production but with laboratory spray-drying equipment. Presence of infectivity was determined before and after spray-drying by microtiter assay in PK 15 cell cultures. Before spray-drying, all three samples contained 10(5.3) tissue culture infectious dose50 (TCID50)/mL of PRV. After four consecutive passages, no viable virus was detected in samples of spray-dried bovine plasma. In Exp. 2, bovine plasma was inoculated with porcine respiratory and reproductive syndrome (PRRS) virus propagated previously in MARC cell culture to provide approximately 10(6.3) TCID50/mL. Three 4-L batches were spray-dried in the same manner as Exp. 1. Before spray-drying, samples contained TCID50 of 10(4.0), 10(3.5), and 10(3.5)/mL, respectively. After four consecutive passages in MARC cell cultures, no viable virus was detected in spray-dried bovine plasma. In Exp. 3, 36 weaned piglets (28 d of age) were fed a common diet for 14 d and were determined to be negative for PRV, PRRS, and porcine parvovirus titer. Afterwards, pigs were allotted to six pens with six pigs per pen and fed diets containing either 0 or 8% SDAP (as-fed basis) for 63 d. The SDAP used in the feed contained antibody (titer 1:400) against porcine parvovirus. Blood samples were collected from pigs on d 0 and 63 to determine whether feeding SDAP caused seroconversion and development of antibodies against parvovirus, PRRS, or PRV. Inclusion of SDAP in the diet improved growth of pigs without seroconversion. Spray-drying conditions used in this study were effective in eliminating viable pseudorabies and PRRS viruses from bovine plasma. In this study, feeding SDAP that contained functional antibodies did not promote seroconversion in na?ve animals.     

Use of infrared thermography to detect signs of rabies infection in raccoons (Procyon lotor).

Infrared thermography was evaluated as a technique to determine if raccoons (Procyon lotor) experimentally infected with rabies virus could be differentiated from noninfected raccoons. Following a 10-day adjustment period, raccoons (n = 6) were infected with a virulent rabies street strain raccoon variant by injection into the masseter muscle at a dose of 2 x 10(4) tissue-culture infectious dose (TCID50) in 0.2 ml (n = 4) or 10(5) TCID50 in 1 ml (n = 2). Five of the six raccoons developed prodromal signs of rabies 17 to 22 days postinoculation (PI) and distinctive clinical signs of furious rabies between 19 and 24 days PI. At the time of euthanasia, which occurred 2 days after the onset of clinical signs of rabies, these five raccoons tested positive for rabies virus in brain tissue. Infrared thermal images of each raccoon were recorded twice daily during the preinoculation and PI periods. No apparent differences were identified among thermal temperatures compared among days for the eye, average body surface, and body temperature recorded from subcutaneous implants throughout the experiment for any of the six raccoons. However, increases in infrared surface temperature of the noses and differences in the visual thermal images of the noses were detected when animals began showing clinical signs of rabies. Differences were detected among the mean infrared nose temperatures for the disease progression intervals (F3.12 = 70.03, P < 0.0001). The mean nose temperature in the clinical rabies stage (30.4 +/- 3.5 degrees C) was significantly elevated over the prodromal stage (F1,12 = 151.85, P < 0.0001). This experiment provides data indicating that infrared thermography can be used in an experimental setting to detect raccoons in the infectious stage and capable of exhibiting clinical signs of rabies.     

Horizontal transmission of pseudorabies virus in cattle

Pseudorabies virus (PRV) was not transmitted horizontally from 3 PRV-infected calves to 2 contact control calves during 4 days of comingling in experiment 1. Although these contact control calves developed clinical signs of pseudorabies when infected intranasally with PRV in experiment 2, they did not transmit PRV to a second pair of contact control calves. However, 1 of 2 pigs comingled with these 4 calves seroconverted. During both experiments, moderate amounts (10(2) to 10(5) TCID50) of PRV were present in the nasal secretions of the infected calves during the contact periods. All infected calves traumatized their nares or periorbital tissue. Infected calves developed a nonsuppurative meningoencephalitis mainly involving the brain stem. Four of the 5 infected calves had nonsuppurative ganglioneuritis and acute lymphoid necrosis of germinal centers. Virus could not be recovered from nasal and tonsillar swab samples from contact-control calves and pigs.     

Semen changes in boars after experimental infection with pseudorabies virus

Two groups of adult boars were inoculated with a field strain of pseudorabies virus (PRV) by intranasal droplet; one group was given 5 x 10(5) median tissue culture infective doses (TCID50), and the other, 5 x 10(6) TCID50. (A third group was maintained as controls.) Ejaculates were examined twice a week for volume, sperm numbers, sperm morphology, and presence of PRV. Severe clinical disease with fever followed administration of the larger virus dose. Death (one boar), testicular degeneration, and transient elevation in spermatozoa with proximal cytoplasmic droplets were seen in different members of this group. The smaller dose resulted in seroconversion, but did not produce signs of disease. In this group, volume, sperm numbers, and sperm morphology did not decline when compared with base-line values or data of control animals. The virus was not isolated from semen. Effects of PRV infection on semen quality in boars seem to be related to the associated clinical signs of systemic disease.     

High- and low-challenge exposure doses used to compare intranasal and intramuscular administration of pseudorabies virus vaccine in passively immune pigs.

We compared 3 modified-live pseudorabies virus (PRV) vaccine strains, administered by the intranasal (IN) or IM routes to 4- to 6-week-old pigs, to determine the effect of high- and low-challenge doses in these vaccinated pigs. At the time of vaccination, all pigs had passively acquired antibodies to PRV. Four experiments were conducted. Four weeks after vaccination, pigs were challenge-exposed IN with virulent virus strain Iowa S62. In experiments 1 and 2, a high challenge exposure dose (10(5.3) TCID50) was used, whereas in experiments 3 and 4, a lower challenge exposure dose (10(2.8) TCID50) was used. This low dose was believed to better simulate field conditions. After challenge exposure, pigs were evaluated for clinical signs of disease, weight gain, serologic response, and viral shedding. When vaccinated pigs were challenge-exposed with a high dose of PRV, the duration of viral shedding was significantly (P less than 0.05) lower, and body weight gain was greater in vaccinated pigs, compared with nonvaccinated challenge-exposed pigs. Pigs vaccinated IN shed PRV for fewer days than pigs vaccinated IM, but this difference was not significant. When vaccinated pigs were challenge-exposed with a low dose, significantly (P less than 0.05) fewer pigs vaccinated IN (51%) shed PRV, compared with pigs vaccinated IM (77%), or nonvaccinated pigs (94%). Additionally, the duration of viral shedding was significantly (P less than 0.05) shorter in pigs vaccinated IN, compared with pigs vaccinated IM or nonvaccinated pigs. The high challenge exposure dose of PRV may have overwhelmed the local immune response and diminished the advantages of the IN route of vaccination.(ABSTRACT TRUNCATED AT 250 WORDS)     

两株猪伪狂犬病病毒变异株的分离鉴定及gB、gC和gE基因的分子特征分析

为探明近年来河南省猪伪狂犬病病毒(PRV)的遗传变异情况,本研究于2017年采集河南漯河和中牟地区疑似伪狂犬病发病养殖场送检的脑组织病料,通过细胞盲传、噬斑纯化、间接免疫荧光试验、Western blotting和透射电镜技术进行病毒分离鉴定。TCID₅₀法测定分离毒株的病毒滴度、生长曲线,通过小鼠感染试验测定分离毒株对小鼠的致死性。对gB、gC和gE基因进行PCR扩增、测序,并与参考毒株序列进行比对分析。结果显示,对PCR鉴定阳性的病料在PK-15细胞盲传后,两份病料在6代内均出现细胞病变,通过间接免疫荧光试验、噬斑纯化和透射电镜技术,成功分离鉴定了两株PRV,分别命名为HeN-LH株及HeN-YM株。分离毒株在PK-15细胞上的生长曲线显示,HeN-LH和HeN-YM株在感染后36 h病毒滴度分别可达10^8.35和10^6.63 TCID₅₀/mL。用不同浓度的病毒接种小鼠,结果显示,HeN-LH和HeN-YM株LD₅₀分别为10^2.13及10^3.25 TCID₅₀。对gB、gC和gE基因全长扩增测序后构建遗传进化树,结果显示,两株PRV毒株与Bartha、Fa和Ea等经典株的亲缘关系相对较远,而与2011年以来国内不同省份分离的PRV变异株亲缘关系较近。氨基酸序列比对分析显示,与其他变异株相似,gB、gC和gE基因均发生了多个氨基酸的变异,且在特定的位点存在特征性的氨基酸插入和缺失。本研究成功分离鉴定了两株PRV变异株,分离株对小鼠均表现出一定的致病性,本试验结果可为河南省伪狂犬病的防控工作和疫苗株的选择提供科学依据。     

Detection of latent pseudorabies virus in porcine tissue, using a DNA hybridization dot-blot assay

A DNA-hybridization dot-blot technique was developed to detect the presence of pseudorabies virus (PRV) DNA in porcine tissue. Seven 32P-nick translated probes of high specific activity were prepared from transformed Escherichia coli plasmids into which Bacillus amyloliquefaciens H (Bam HI) restriction fragments of PRV-DNA had been inserted. Samples of DNA that had been extracted from porcine tissue or from PRV grown in tissue culture were transferred to nitrocellulose paper, using a microsample filtration manifold and were hybridized to the probes under high-stringency conditions. Under optimal hybridization conditions, the minimum detection amount of PRV-DNA was 10(-11) g, which is equivalent to 1 copy of the PRV genome/80 host cells. Four probes did not show cross hybridization with DNA extracted from tissues of known PRV-negative swine, and these were subsequently used to detect PRV-DNA in infected porcine tissues. Generally, correlation between virus isolation and hybridization data was good for tissues from swine that had died of acute PRV infection. Furthermore, PRV-DNA was present in specific tissues of all 4 seropositive swine that had recovered from pseudorabies and in which no infective virus or viral products were detected at necropsy. Pseudorabies virus DNA was present in the rostralis cerebral cortex (n = 2) or in the medulla oblongata (n = 1) and trigeminal ganglion (n = 1). This probably indicated the portal of entry of the virus into the CNS. In another seropositive pig, there was evidence of a productive infection in the tonsils, although virus was not isolated in a tissue culture system.(ABSTRACT TRUNCATED AT 250 WORDS)     

Virus isolation and immune responses in susceptible swine exposed with pseudorabies virus (Shope strain).

Eighteen seronegative swine weighing from 9 to 11 kg were exposed intranasally with the Shope strain of pseudorabies virus (PRV) and were observed for 21 days in an experiment to detect virus shedding and immune responses. All swine had PRV in their nasal passages at 7 days after exposure; they also had precipitating antibodies to PRV as determined by the microimmunodiffusion test (MIDT) and very low levels of virus-neutralizing (VN) antibodies. The PRV was isolated from only 2 swine at postexposure day 14; all swine were MIDT positive, and VN titers ranged from 4 to 128. Virus was not isolated from the swine at 21 days after exposure, but all were MIDT positive; VN titers ranged between 8 and greater than or equal to 256.     

绵羊感染伪狂犬病的病理学观察与病毒分离鉴定

为了确诊1例疑似绵羊伪狂犬病病例,本试验以上海郊区某羊场发病绵羊的病料为研究对象进行了病理学观察、病毒分离和鉴定。病理组织学变化显示,发病羊大脑组织神经元发生广泛性变性、坏死并伴有嗜神经现象,神经元周围出现胶质细胞增生。病料接种BHK-21细胞,细胞出现病变,间接免疫荧光试验和荧光定量PCR检测结果证实所分离的病毒为伪狂犬病病毒。流行病学调查结果表明,绵羊伪狂犬病可能是由猪伪狂犬病病毒感染引起的。通过免疫接种猪伪狂犬病弱毒疫苗,绵羊伪狂犬病疫情得到及时控制。     

猪伪狂犬病病毒GXBB株的分离鉴定及gE基因的克隆分析

从广西玉林博白某猪场采集的发病仔猪大脑和内脏病料中分离到一株病毒。病毒接种家兔后引起典型的奇痒、神经症状,接种PK-15细胞出现典型的细胞病变,病毒效价（TCID₅₀）为10^-7.22/0.1 ml。设计扩增PRV gE胞外区基因的引物,能扩增出约947 bp的特异性片段,将扩增出的目的片段进行克隆、测序,并与国内外不同PRV毒株进行分析比较,发现该毒株与国内MinA株、Ea株、SH株、LA株、GXB株、GXW株核苷酸同源性在98.7%～99.4%之间,氨基酸同源性在98.1%～99.1%之间,上述结果证实该分离毒株为伪狂犬病病毒,命名为GXBB株。GXBB株与国内流行毒株同源性很高,说明目前广西PRV流行株变异不大。这为下一步广西伪狂犬病的预防和净化工作提供科学的理论基础。     

猪伪狂犬病病毒JSSQ2013株的分离鉴定及重要功能基因序列分析

为了解江苏省猪伪狂犬病病毒(Pseudorabies virus,PRV)野毒株的特点,本研究从2013年采自江苏省宿迁市的疑似PRV感染病料中分离纯化了一株PRV病毒,对其进行了PCR和间接免疫荧光法(IFA)鉴定,并进一步在Vero细胞上测定该分离株的病毒滴度TCID50和一步生长曲线,扩增其gB、gC、gD和gE基因进行序列比对及分子遗传进化分析,并将该分离株分别接种新西兰白兔和15日龄仔猪研究其致病性。结果显示,该病毒为一株PRV,命名为PRV JSSQ2013株,纯化后的病毒滴度为10^7.8 TCID50/ml;生长曲线测定显示在感染20h后病毒滴度即达到最高,为10^8.6 TCID50/ml。与我国近几年分离的PRV变异株序列相比,PRV JSSQ2013株的gB、gC、gD和gE基因核苷酸序列同源性分别为99.5~99.6%、99.5~99.6%、99.5~99.6%和98.7~99.7%,氨基酸序列同源性分别为98.9~99.0%、99.5~99.7%、99.0~99.2%和98.1~99.3%,均高于其与经典毒株(Ea、Fa和SC株)和欧美毒株(Becker、Kaplan、Bartha、Kolchis和NIA3)的同源性;基于gB、gC、gD和gE基因的遗传进化树分析均显示PRV JSSQ2013株与国内近几年分离的PRV变异株属同一分支。该病毒接种新西兰白兔后均出现典型的PR症状,如厌食、兴奋、啃咬或用爪挠接种部位等典型症状,且在48h内全部死亡;接种仔猪后第1天开始出现典型的PR症状,第5天全部死亡。以上结果证实,从江苏省宿迁市采集的疑似PRV感染病料中分离到一株强毒力的PRV变异株。本研究为了解江苏PRV分子流行特征、丰富我国PRV分子流行病学资料及新型疫苗的研制奠定了基础。     

3种非猪瘟病毒单独或混合感染对猪瘟弱毒疫苗免疫效力的影响

将 2 0头 9月龄左右猪瘟、伪狂犬、猪繁殖与呼吸障碍综合征抗原、抗体阴性猪分成 6组 ,分别利用猪细小病毒(PPV)、猪伪狂犬病毒 (PRV)和猪繁殖与呼吸障碍综合征病毒 (PRRSV)单独或混合感染。 7d后连同对照猪 4头 ,免疫接种猪瘟兔化弱毒疫苗 (HCL V) ,13d后连同 4头阴性对照猪一起攻击猪瘟石门强毒。整个试验期间分别每天测温 ,观察临床症状 ,每周采集扁桃体和血样做各种病毒抗原及抗体检测。结果表明 ,非猪瘟病毒感染 7d后 ,所有各组猪均从体内检测到了相应感染的病原 ,表明 3种非猪瘟病毒感染成功。在攻击猪瘟石门强毒后 2周 ,感染了非猪瘟病毒后接种 HCL V疫苗的 4个免疫组 12头猪除 1头外 ,11头全为猪瘟病毒 (HCV)抗原检测阳性 ,且多呈强阳性 ;而单一 HCL V疫苗免疫组在猪瘟强毒攻击后检测不到 HCV;所有 HCL V疫苗免疫猪均存活 ,而非免疫对照组 4头猪全部在攻毒 16 d内死亡。     

伪狂犬病病毒弱毒株LY株的分离鉴定

从辽阳某猪场的10日龄仔猪中分离到1株病毒,经纯化后测得其毒价为107.29TCID50/mL.细胞中和试验表明,该病毒能被猪伪狂犬病病毒标准阳性血清所中和.电镜下可见到典型的疱疹病毒粒子,具有囊膜及外周纤突.所分离的病毒对氯仿、胰蛋白酶、乙醚敏感,在pH5.0～9.0下稳定,56℃ 30 min可以灭活.应用特异性引物,通过PCR能扩增出伪狂犬病病毒1 240 bp的gD基因.分离病毒对3日龄乳鼠有一定的致病力,但对家兔、3～5日龄仔猪及妊娠母猪都有很高的安全性.用不同剂量的病毒培养液肌肉注射于3～5日龄仔猪,14 d后用105.7TCID50伪狂犬病病毒强毒攻击,所有试验仔猪均可得到有效保护.用分离毒免疫母猪,其后代可获高滴度的母源抗体,15日龄的仔猪能抵抗105.7TCID50强毒的攻击.试验的结果初步说明,所分离的病毒为伪狂犬病病毒(命名为PRV LY株),并可能是一株弱毒株,而且具有很好的免疫保护作用.     

Isolation,Identification and Phylogenetic Analysis of Important Functional Genes of Porcine Pseudorabies Virus LC Strain

To find out the reason of the reproductive failure in pregnant sows in a hoggery in Guangdong, the mixture with brain, lymph nodes and lungs of farm abortion stillbirth were identified by PCR, virus isolation and culture, tissue culture infective dose (TCID₅₀) assay, homology and phylogenetic analysis of the important functional genes (gB, gC, gD and gE) and animal test. The results showed that the mixture was proved to be porcine pseudorabies virus (PRV) positive samples. The typical cytopathogenic effect was induced in the third passage of Vero cell and the titer of the fifth passage was 10^-6.8/0.1 mL. The sequence analysis and phylogenetic relationship of gB, gC, gD and gE genes showed that it was a Chinese PRV variant, which was named as LC strain. The typical pseudorabies clinical and pathological symptoms were presented in 12-week-old piglets inoculated with LC strain. The results demonstrated that a local pseudorabies virus had been isolated, suggesting that the Bartha-K61 vaccine was not fully effective for controlling the current epidemic of pseudorabies in China.     

猪伪狂犬病病毒LC株的分离鉴定及其重要功能基因的进化分析

为确诊广东某猪场母猪流产发病原因,本研究收集该猪场流产死胎的脑、淋巴结、肺脏混合液,进行PCR鉴定、病毒分离培养、半数组织培养感染剂量（tissue culture infective dose,TCID₅₀）测定、猪伪狂犬病病毒（pseudorabies virus,PRV）重要功能基因（gB、gC、gD、gE）序列测定和进化分析及动物回归试验。结果显示,病料混合液为PRV阳性,接种Vero细胞传至第3代即出现稳定的细胞病变（CPE）,第5代TCID₅₀达到10^-6.8/0.1 mL,PRV gB、gC、gD、gE基因序列测定、同源性及进化树分析显示为,PRV中国变异株,命名为LC株。动物试验显示,LC株对12周龄猪具有一定致病性,可形成PRV典型临床症状及病理变化。本研究分离到一株PRV流行毒株,推测当前使用疫苗Bartha-K61株尚无法完全控制新毒株的流行。