DNA sequence of the gene for pseudorabies virus gp50, a glycoprotein without N-linked glycosylation.

The DNA sequence was determined for a region of the pseudorabies virus (PRV) genome to which a mutation defining resistance to a monoclonal antibody has been mapped (M. W. Wathen and L. M. K. Wathen, J. Virol., 51:57-62, 1984). This sequence was found to contain an open reading frame that did not include an amino acid sequence directing N-linked glycosylation. This open reading frame was expressed in uninfected Chinese hamster ovary cells to produce the PRV glycoprotein gp50. When PRV-infected Vero cells were incubated in the presence of tunicamycin, the gp50 that was produced had an identical molecular weight to that produced in the absence of drug. When infected cells were incubated in the presence of monensin, the molecular weight of gp50 was reduced from 60,000 to 45,000, but was not sensitive to endo-beta-N-acetylglucosaminidase H. These observations led to the conclusion that gp50 does not contain N-linked carbohydrate, as predicted from the DNA sequence. A region of the amino acid sequence and the positions of the cysteine residues of PRV gp50 are homologous to glycoprotein D of herpes simplex virus.     

Glycoprotein gp50-negative pseudorabies virus: a novel approach toward a nonspreading live herpesvirus vaccine.

Essential herpesvirus glycoproteins are involved in membrane fusion processes during infection, e.g., viral penetration and direct cell-to-cell transmission. We previously showed that the gD-homologous glycoprotein gp50 of pseudorabies virus (PrV) is essential for virus entry into target cells but proved to be dispensable for direct viral cell-to-cell spread in cell culture (I. Rauh and T. C. Mettenleiter, J. Virol. 65:5348-5456, 1991). For gp50-negative (gp50-) viruses, after phenotypic complementation necessary for primary infection, the only means of viral spread is by way of direct cell-to-cell transmission. In contrast, virus mutants lacking the essential gB-homologous glycoprotein gII after phenotypic complementation are only able to infect primary target cells and are blocked in further viral spread. To analyze how these in vitro phenotypes translate into virus replication in the animal, mice were infected intranasally with gp50- or gII- PrV mutants after prior phenotypic complementation by propagation on cell lines providing the essential glycoprotein in trans. Our results show that whereas the gII- mutants did not cause disease or any symptoms, gp50- mutants derived from two different PrV strains were fully virulent, with animals exhibiting severe symptoms ultimately leading to death. However, free infectious virus could not be recovered from either gp50- or gII- PrV-infected animals. We conclude that direct cell-to-cell transmission as the only means of viral spread of the gp50- mutants is sufficient for a full virulent phenotype in mice. After infection of pigs with phenotypically complemented gp50- PrV, only mild symptoms were observed, whereas the gII- mutant was totally avirulent. In both cases, shedding of infectious virus did not occur, in contrast to results with animals infected by gX- PrV that showed severe signs of disease and extensive virus shedding. After challenge infection with the highly virulent NIA-3 strain, the previously gII- PrV-infected animals exhibited severe symptoms, whereas the gp50- PrV-infected pigs showed a significant level of protection. In conclusion, vaccination with a PrV mutant lacking glycoprotein gp50, which is unable to spread between animals because of a lack of formation of free infectious virions, can confer on pigs protection against challenge infection. These results provide the basis for the development of new, nonspreading live herpesvirus vaccines based on gp50- PrV mutants.     

Isolation and characterization of a heat-inducible simian virus 40 mutant.

We have isolated a new type of temperature-sensitive mutant of simian virus 40 (SV40) that is capable of productive infection in permissive cells but not of maintenance of viral DNA integration in transformed cells at the conditional temperature. Virus development is induced when cells transformed by this mutant are shifted to temperatures above 39 degrees C, but is not induced below this temperature. The plaque-purified, temperature-sensitive mutant virus confers heat inducibility to new host cells, indicating that the conditional function is a property of the viral genome. Unlike previously described temperature-sensitive SV40 mutants, in (ts)-1501 is capable of productive infection in permissive cells at the conditional temperature. The morphology, growth, and oncogenicity of in (ts)-1501-transformed cells at 37 degrees C are similar to those of cell lines transformed by wild-type SV40. HK10-c2(in(ts)-1501), a cloned cell line, transformed at 37 degrees C by the mutant virus, exhibits a transient increase in DNA synthesis before cell death at the conditional temperature. Many properties of in(ts)-1501 are analogous to those of the heat-inducible mutants of bacteriophages in which a heat-inactivated protein is responsible for the stable integration of the prophage in the bacterial chromosome.     

Isolation and characterization of a Chinese hamster ovary mutant cell line with altered sensitivity to vaccinia virus killing.

The Chinese hamster ovary (CHO) cell line is nonpermissive for vaccinia virus, and translation of viral intermediate genes was reported to be blocked (A. Ramsey-Ewing and B. Moss, Virology 206:984-993, 1995). However, cells are readily killed by vaccinia virus. A vaccinia virus-resistant CHO mutant, VV5-4, was isolated by retroviral insertional mutagenesis. Parental CHO cells, upon infection with vaccinia virus, die within 2 to 3 days, whereas VV5-4 cells preferentially survive this cytotoxic effect. The survival phenotype of VV5-4 is partial and in inverse correlation with the multiplicity of infection used. In addition, viral infection fails to shut off host protein synthesis in VV5-4. VV5-4 was used to study the relationship of progression of the virus life cycle and cell fate. We found that in parental CHO cells, vaccinia virus proceeds through expression of viral early genes, uncoating, viral DNA replication, and expression of intermediate and late promoters. In contrast, we detect only expression of early genes and uncoating in VV5-4 cells, whereas viral DNA replication appears to be blocked. Consistent with the cascade regulation model of viral gene expression, we detect little intermediate- and late-gene expression in VV5-4 cells. Since vaccinia virus is known to be cytolytic, isolation of this mutant therefore demonstrates a new mode of the cellular microenvironment that affects progression of the virus life cycle, resulting in a different cell fate. This process appears to be mediated by a general mechanism, since VV5-4 is also resistant to Shope fibroma virus and myxoma virus killing. On the other hand, VV5-4 remains sensitive to cowpox virus killing. To examine the mechanism of VV5-4 survival, we investigated whether apoptosis is involved. DNA laddering and staining of apoptotic nuclei with Hoechst 33258 were observed in both CHO and VV5-4 cells infected with vaccinia virus. We concluded that the cellular pathway, which blocks viral DNA replication and allows VV5-4 to survive, is independent of apoptosis. This mutant also provides evidence that an inductive signal for apoptosis upon vaccinia virus infection occurs prior to viral DNA replication.     

Characterization and mapping of a nonessential pseudorabies virus glycoprotein.

Antigenic variants of pseudorabies virus (PRV) containing mutations in a viral glycoprotein with a molecular weight of 82,000 (gIII) were isolated by selecting for resistance to a complement-dependent neutralizing monoclonal antibody (MCA82-2) directed against gIII. These mutants were completely resistant to neutralization with MCA82-2 in the presence of complement. Two mutants selected for further studies either did not express gIII or expressed an improperly processed form of the glycoprotein. The mutations were also associated with an altered plaque morphology (syncytium formation). The gIII gene was mapped by marker rescue of a gIII- mutant with cloned restriction enzyme fragments to the long unique region of the PRV genome between 0.376 and 0.383 map units. This corresponds to the map location of a glycoprotein described by Robbins et al. (J. Mol. Appl. Gen. 2:485-496, 1984). Since gIII is nonessential for viral replication in cell culture and has several other characteristics in common with the herpes simplex virus glycoprotein gC, gIII may represent the PRV equivalent to herpes simplex virus gC.     

Isolation and characterization of a mutant of Schwanniomyces castellii with altered respiration

We have tried to isolate respiratory deficient mutants of the amylolytic yeast Schwanniomyces castellii CBS 2863 after mutagenesis with acriflavine. One of the mutants called DR 12 has been studied in more detail. Pasteur effect present in the wild-type is lost in the mutant, on the contrast an obvious Crabtree effect was observed: fermentation was almost as active in aerobiosis as in anaerobiosis. Moreover, the rate of anaerobic fermentation of the mutant was almost twice that of the wild type. This mutant was cytrochrome b-deficient while the amount of the other cytochromes was larger than in the wild-type. Moreover, the level of these remaining cytochromes in the mutant was higher on non-repressive medium than on glucose medium. However, the fact that the mutant DR 12 retained a cyanide-sensitive respiration and that it was able to grow on ethanol as a non-fermentable substrate is noteworthy.     

Reduced yield of infectious pseudorabies virus and herpes simplex virus from cell lines producing viral glycoprotein gp50.

Pseudorabies virus (PRV) glycoprotein gp50 is the homolog of herpes simplex virus (HSV) glycoprotein D. Several cell lines that constitutively synthesize gp50 were constructed. Vero cells, HeLa cells, and pig kidney (MVPK) cells that produce gp50 all gave reduced yields of PRV and HSV progeny viruses when compared with the parent cell line or the same cell line transfected to produce a different protein. The reduction in virus yield was greatest at low multiplicities of infection. The Vero and HeLa cells that produce gp50 showed an even greater reduction in HSV yield than in PRV yield. This phenomenon may be an example in a herpesvirus of the interference observed in retroviruses or cross-protection in plant virus systems.     

Isolation and characterization of Pseudomonas aeruginosa PAO mutant that produces altered elastase.

Pseudomonas aeruginosa PAO mutants defective in elastase were isolated by plate assays of nitrosoguanidine-mutagenized clones. A total of 75 elastase mutants were isolated from 43,000 mutagenized clones. One mutant (PAO-E64) was apparently identical to the parental strain except for its deficiency in elastase activity. This mutant produced an enzyme which was antigenically indistinguishable from parental elastase. Furthermore, equal levels of elastase antigen were produced by this mutant and its parental strain. The mutant elastase, however, had greatly reduced enzymatic activity. Mutant PAO-E64 is presumed to have a mutation in the structural gene for elastase. We have designated the genotype of the mutation in PAO-E64 as lasA1.     

Isolation,characterization, and mapping of the stay green mutant in rice

Leaf color turns yellow during senescence due to the degradation of chlorophylls and photosynthetic proteins. A stay green mutant was isolated from the glutinous japonica rice Hwacheong-wx through N-methyl-N-nitrosourea mutagenesis. Leaves of the mutant remained green, while turning yellow in those of the wild-type rice during senescence. The stay green phenotype was controlled by a single recessive nuclear gene, tentatively symbolized as sgr(t). All the phenotypic characteristics of the mutant were the same as those of the wild-type lines except for the stay green trait. The leaf chlorophyll concentration of the mutant was similar to that of the wild-type before heading, but decreased steeply in the wild-type during grain filling, while very slowly in the mutant. However, no difference in photosynthetic activity was observed between the stay green mutant and the yellowing wild-type leaves, indicating that senescence is proceeding normally in the mutant leaves and that the mutation affects the rate of chlorophyll degradation during the leaf senescence. Using phenotypic and molecular markers, we mapped the sgr(t) locus to the long arm of chromosome 9 between RFLP markers RG662 and C985 at 1.8- and 2.1-cM intervals, respectively. Received: 29 April 2001 / Accepted: 17 July 2001     

Isolation and characterization of a Neurospora crassa mutant altered in the alpha polypeptide of glutamine synthetase.

We report the isolation and characterization of a Neurospora crassa glutamine synthetase (GS) mutant altered in one of the two polypeptides (GS alpha) of this enzyme. We used the gln-1bR8 mutant strain that synthesizes only the GS alpha monomer and lacks the GS beta monomer and selected for growth in minimal medium in the presence of alpha-methyl-DL-methionine-SR-sulfoximine (alpha-me-MSO), an inhibitor of GS activity. The GS activity of the gln-1bR8;alpha-me-MSOR strain drastically reduced its transferase activity and only slightly reduced its synthetase activity, and it was resistant to inhibition by alpha-me-MSO and L-methionine-DL-sulfoximine. The mutation that overcame the inhibitory effect of alpha-me-MSO also altered the antigenic, kinetic, and physical properties of GS alpha. The low GS activity of the alpha-me-MSO-resistant strain was compensated for by a higher glutamate/glutamine ratio and a lower glutamate synthase activity, allowing this strain to grow as well as the parental strain. The mutation that conferred resistance to alpha-me-MSO was not linked to the gln-1bR8 mutation, providing direct evidence of the existence of two genes involved with the structure of the two polypeptides of N. crassa GS.     

Identification and characterization of pseudorabies virus dUTPase.

Sequence analysis within the long segment of the pseudorabies virus (PrV) genome identified an open reading frame of 804 bp whose deduced protein product of 268 amino acids exhibited homology to dUTPases of other herpesviruses. The gene was designated UL50 because of its colinearity with the homologous gene of herpes simplex virus type 1. An antiserum raised against a bacterially expressed fragment of PrV UL50 specifically detected a 33-kDa protein in lysates of infected cells, which is in agreement with the predicted molecular mass of the PrV UL50 protein. A UL50-negative PrV mutant (PrV UL50-) was constructed by the insertion of a beta-galactosidase expression cassette into the UL50 coding sequence. A corresponding rescuant (PrV UL50resc) was also isolated. The interruption of the UL50 gene led to the disappearance of the 33-kDa protein, whereas restoration of UL50 gene expression restored detection of the 33-kDa protein. Enzyme activity assays confirmed that UL50 of PrV codes for a dUTPase which copurifies with nuclei of infected cells. PrV UL50- replicated with an only slightly reduced efficiency in epithelial cells in culture compared with that of its parental wild-type virus strain. Our results thus demonstrate that UL50 of PrV encodes a protein of 33 kDa with dUTPase activity which copurifies with nuclei of infected cells and is dispensable for replication in cultured epithelial cells.     

Isolation and mapping of a mutant penicillin G acylase with altered substrate specificity from Escherichia coli

Summary Penicillin G acylase of Escherichia coli ATCC 11105 catalyzes hydrolysis as wellas synthesis of penicillin G. In this work a recombinant penicillin G acylase genewas mutagenized in vivo. A mutant with altered penicillin G acylase was selectedby its ability to grow with phthalyl-L-leucine as sole source of leucine. Themutant enzyme obtained was deficient in hydrolyzing penicillin G. A mutation ofGly359 to aspartic acid was mapped first by construction of chimeric pac genescomposed of wild type and mutant DNA, followed by nucleotide sequencing.     

Isolation and characterization of pseudorabies virus from a wolf (Canis lupus) from Belgium

Aujeszky’s disease is an economically important disease in domestic pigs caused by the alphaherpesvirus pseudorabies virus (PRV). However, also wild boars are a natural reservoir for the virus, and this can lead to infection of wildlife carnivore species. Three wolves held in the wildlife park of Han-sur-Lesse in the province of Namur in Belgium were suspected to be infected with PRV based on the nervous symptoms they showed after being fed with wild boar offal. The diagnosis was confirmed for a female wolf by a positive real-time PCR detecting PRV. The virus was isolated from the brain tissue of the wolf and characterized by restriction fragment length polymorphism analysis and phylogenetic analysis. The obtained BamHI restriction fragment pattern of the wolf isolate was similar to that of the reference strain Kaplan, thereby characterizing it as a type Ip isolate. Type I PRV strains, and particularly subtype Ip, are predominant in European wild boar. Phylogenetic analysis based on the sequence of a fragment of glycoprotein C showed that the Belgian isolate belonged to cluster B and that the sequence was identical to that of wild boar isolates from southwestern Germany, eastern France, and Spain. This study is the first report of Aujeszky’s disease in wolves and shows that they are susceptible to PRV by eating infected wild boar offal leading to fatal neurological disease. This illustrates the possible implications of PRV-infected wild boar for the conservation of wolves and other carnivore species.     

Identification and characterization of a novel structural glycoprotein in pseudorabies virus, gL.

Herpesvirus envelope glycoproteins play important roles in the interaction between virions and target cells. In the alphaherpesvirus pseudorabies virus (PrV), seven glycoproteins that all constitute homologs of glycoproteins found in herpes simplex virus type 1 (HSV-1) have been characterized, including a homolog of HSV-1 glycoprotein H (gH). Since HSV-1 gH is found associated with another essential glycoprotein, gL, we analyzed whether PrV also encodes a gL homolog. DNA sequence analysis of a corresponding part of the UL region adjacent to the internal inverted repeat in PrV strains Kaplan and Becker revealed the presence of two open reading frames (ORF). Deduced proteins exhibited homology to uracil-DNA glycosylase encoded by HSV-1 ORF UL2 (54% identity) and gL encoded by HSV-1 ORF UL1 (24% identity), respectively. To identify the PrV UL1 protein, rabbit antisera were prepared against two synthetic oligopeptides that were predicted by computer analysis to encompass antigenic epitopes. Sera against both peptides reacted in Western blots of purified virions with a 20-kDa protein. The specificity of the reaction was demonstrated by peptide competition. Since the PrV UL1 sequence did not reveal the presence of a consensus N-linked glycosylation site, concanavalin A affinity chromatography and enzymatic deglycosylation of virion glycoproteins were used to ascertain that the PrV UL1 product is O glycosylated. Therefore, we designated this protein PrV gL. Analysis of mutant PrV virions lacking gH showed that concomitantly with the absence of gH, gL was also missing in purified virions. In summary, we identified and characterized a novel structural PrV glycoprotein, gL, which represents the eighth PrV glycoprotein described. In addition, we show that virion location of PrV gL is dependent on the presence of PrV gH.     

Isolation and characterization of magbane, a magnesium-lethal mutant of paramecium.

Discerning the mechanisms responsible for membrane excitation and ionic control in Paramecium has been facilitated by the availability of genetic mutants that are defective in these pathways. Such mutants typically are selected on the basis of behavioral anomalies or resistance to ions. There have been few attempts to isolate ion-sensitive strains, despite the insights that might be gained from studies of their phenotypes. Here, we report isolation of "magbane," an ion-sensitive strain that is susceptible to Mg2+. Whereas the wild type tolerated the addition of > or =20 mm MgCl2 to the culture medium before growth was slowed and ultimately suppressed (at >40 mm), mgx mutation slowed growth at 10 mm. Genetic analysis indicated that the phenotype resulted from a recessive single-gene mutation that had not been described previously. We additionally noted that a mutant that was well described previously (restless) is also highly sensitive to Mg2+. This mutant is characterized by an inability to control membrane potential when extracellular K+ concentrations are lowered, due to inappropriate regulation of a Ca2+-dependent K+ current. However, comparing the mgx and rst mutant phenotypes suggested that two independent mechanisms might be responsible for their Mg2+ lethality. The possibility that mgx mutation may adversely affect a transporter that is required for maintaining low intracellular Mg2+ is considered.     

Role of essential glycoproteins gII and gp50 in transneuronal transfer of pseudorabies virus from the hypoglossal nerves of mice.

The propagation of pseudorabies virus (PrV) mutants deficient in essential glycoproteins gp50 and gII was studied after inoculation of transcomplemented gp50- and gII- PrV into the motor hypoglossal (XII) nerves of mice. In this model, viral spread from the infected XII motoneurons involves specific transneuronal transfer to connected cells and local, nonspecific transfer. For comparison, a PrV mutant lacking the nonessential nonstructural glycoprotein gX was included. Although the efficiencies of first-cycle replication were similar for the three viruses, only gX- and gp50- progeny mutants could spread from XII motoneurons via transneuronal and local transfer. The extents of transfer of gX- and gp50- PrV were comparable. The results show that the absence of gp50 does not alter the pattern of transneuronal or local spread of PrV, whereas gII is essential for both processes.     

Envelope glycoprotein gp50 of pseudorabies virus is essential for virus entry but is not required for viral spread in mice.

Phenotypically complemented pseudorabies virus gp50 null mutants are able to produce plaques on noncomplementing cell lines despite the fact that progeny virions are noninfectious. To determine whether gp50 null mutants and gp50+gp63 null mutants are also able to replicate and spread in animals, mice were infected subcutaneously or intraperitoneally. Surprisingly, both gp50 mutants and gp50+gp63 double mutants proved to be lethal for mice. In comparison with the wild-type virus, gp50 mutants were still highly virulent, whereas the virulence of gp50+gp63 mutants was significantly reduced. Severe signs of neurological disorders, notably pruritus, were apparent in animals infected with the wild-type virus or a gp50 mutant but were much less pronounced in animals infected with a gp50+gp63 or gp63 mutant. Immunohistochemical examination of infected animals showed that all viruses were able to reach, and replicate in, the brain. Examination of visceral organs of intraperitoneally infected animals showed that viral antigen was predominantly present in peripheral nerves, suggesting that the viruses reached the central nervous system by means of retrograde axonal transport. Infectious virus could not be recovered from the brains and organs of animals infected with gp50 or gp50+gp63 mutants, indicating that progeny virions produced in vivo are noninfectious. Virions that lacked gp50 in their envelopes, and a phenotypically complemented pseudorabies virus gII mutant (which is unable to produce plaques in tissue culture cells), proved to be nonvirulent for mice. Together, these results show that gp50 is required for the primary infection but not for subsequent replication and viral spread in vivo. These results furthermore indicate that transsynaptic transport of the virus is independent of gp50. Since progeny virions produced by gp50 mutants are noninfectious, they are unable to spread from one animal to another. Therefore, such mutants may be used for the development of a new generation of safer (carrier) vaccines.     

Identification and characterization of pseudorabies virus glycoprotein H.

On the basis of DNA sequence analysis, it has recently been shown that the pseudorabies virus (PrV) genome encodes a protein homologous to glycoprotein H (gH) of other herpesviruses (B. Klupp and T.C. Mettenleiter, Virology 182:732-741, 1991). To obtain antibodies specific for gH(PrV), rabbits were immunized with synthetic peptides representing two potential epitopes on gH(PrV) as predicted by computer analysis. The antipeptide sera recognized the gH precursor polypeptide pgH translated in vitro from an in vitro-transcribed mRNA. Western blot (immunoblot) analyses of purified pseudorabies virions using these antisera revealed specific reactivity with a protein with an apparent molecular mass of 95 kDa. Specificity of the reaction could be demonstrated by competition experiments with respective peptides. Analysis of PrV deletion mutants defective in genes encoding known glycoproteins proved that gH(PrV) constitutes a novel PrV glycoprotein not previously found. Treatment of purified virion preparations with endoglycosidase H reduced the apparent molecular mass of gH(PrV) to 90 kDa, indicating the presence of N-linked high-mannose (or hybrid) carbohydrates in mature virions. Removal of all N-linked carbohydrates by N-glycosidase F resulted in a product of 76 kDa. In summary, our results demonstrate the existence of gH in PrV as a structural component of the virion.     

Isolation, characterization, and complementation of a motility mutant of Spiroplasma citri.

The helical mollicute Spiroplasma citri, when growing on low-agar medium, forms fuzzy colonies with occasional surrounding satellite colonies due to the ability of the spiroplasmal cells to move through the agar matrix. In liquid medium, these helical organisms flex, twist, and rotate rapidly. By using Tn4001 insertion mutagenesis, a motility mutant was isolated on the basis of its nondiffuse, sharp-edged colonies. Dark-field microscopy observations revealed that the organism flexed at a low frequency and had lost the ability to rotate about the helix axis. In this mutant, the transposon was shown to be inserted into an open reading frame encoding a putative polypeptide of 409 amino acids for which no significant homology with known proteins was found. The corresponding gene, named scm1, was recovered from the wild-type strain and introduced into the motility mutant by using the S. citri oriC plasmid pBOT1 as the vector. The appearance of fuzzy colonies and the observation that spiroplasma cells displayed rotatory and flexional movements showed the motile phenotype to be restored in the spiroplasmal transformants. The functional complementation of the motility mutant proves the scm1 gene product to be involved in the motility mechanism of S. citri.     

猪伪狂犬病病毒流行株HLJ-01的分离鉴定及致病性分析

【背景】自2011年以来,猪伪狂犬病毒(pseudorabies virus,PRV)发生变异,经典的疫苗株已不能完全抵抗PRV变异株的感染,国内多个猪场出现伪狂犬病的暴发,PRV变异毒株开始在我国大规模流行。【目的】通过分离PRV流行变异毒株,并对其进行遗传进化和致病性分析,为PRV流行病学调查及疫苗研制提供实验数据。【方法】采集黑龙江某猪场感染PRV的脑组织病料,根据GenBank PRV gE和gB保守序列设计引物,进行PCR鉴定。通过对gE和gC基因进行序列测定和遗传进化分析。利用BHK-21细胞分离病毒,采用噬斑纯化方法对病毒进行纯化。通过电镜、间接免疫荧光对病毒进行鉴定,测定病毒生长曲线并进行致病性研究。【结果】经PCR和测序鉴定分离株为PRV流行株,将其命名为HLJ-01。遗传进化分析结果显示,该分离毒株与我国近几年分离的流行变异株位于同一分支;氨基酸序列分析结果显示,gE和gC存在国内流行变异株的特征序列,表明该分离毒株为流行变异株。生长曲线显示,分离株HLJ-01在感染48h时滴度最高(10^8.5TCID₅₀/mL)。电镜观察结果显示,病毒颗粒直径约150nm,呈球形,有囊膜,囊膜外有放射状纤突,呈现典型PRV病毒特征。动物感染实验结果显示,10^7.0TCID₅₀剂量感染组死亡率为100%;10^6.0TCID₅₀剂量感染组死亡率为80%;10^5.0TCID₅₀剂量感染组死亡率为60%。仔猪在接种病毒后均出现PRV感染的典型症状和病理变化,证实分离毒株对仔猪有较强致病力。【结论】分离获得一株猪伪狂犬病毒,经鉴定该分离株为流行变异株,而且具有较强的致病力,这为PRV流行病学分析及疫苗候选株的筛选奠定了基础。