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1.
 研究旨在获得PCV2a和PCV2b的拯救毒株。对筛选得到的PCV2a和PCV2b感染性克隆分别进行酶切,使酶切得到的全长基因组DNA自身环化并分别转染PK15细胞。经IFA和PCR验证,确认成功拯救出两亚型PCV2病毒。病毒传至第9代时对PCV2a和PCV2b的毒价分别进行测定,结果显示PCV2a的毒价为103.5TCID50/mL, PCV2b的毒价为104.6TCID50/mL。本试验为分型特异性序列与病毒致病力相关性的研究打下了基础.  相似文献   

2.
Multiply-primed rolling-circle amplification (MPRCA) was used to amplify porcine circovirus type 2 (PCV2) genomes isolated from tissues of pigs with signs of post-weaning multisystemic wasting syndrome (PMWS). Two of the amplified PCV2 genomes were cloned in prokaryotic plasmids and sequenced. Both were nearly identical (1767 nt) except for one silent substitution in the region coding for the capsid protein (ORF2). In addition, they showed high nucleotide sequence similarity with PCV2 isolates from others countries (93–99%). To investigate whether the MPRCA amplified PCV2 genomes could be used to produce infectious virus, the cloned genomes were isolated from the plasmids, recircularized and used for transfection in PK-15 cells. This procedure led to the production of infectious virus to titres up to 105.55 TCID50/mL. It was concluded that MPRCA is a useful tool to amplify PCV2 genomes aiming at sequencing and virus isolation strategies, where particularly useful is the fact that it allows straightforward construction of PCV2 infectious clones from amplified genomes. However, it was less sensitive than PCR for diagnostic purposes.  相似文献   

3.
Post-weaning Multisystemic Wasting Syndrome (PMWS) has been identified in most swine-producing countries worldwide. The disease has resulted in significant health challenges and economic damage to the swine industry. The aim of this study was to determine horizontal transmission of porcine circovirus type 2 (PCV2) and to examine viral dynamics in pigs in a controlled PMWS transmission study. In the study pigs from PMWS-affected herds and non-affected herds were permitted to have close contact (same pen), nose-to-nose contact (to pigs in neighbouring pens) or no physical contact (pen across the aisle and pens in other compartments). By DNA sequence analysis, eight variants of genotype PCV-2b were identified in the research facility. From the spread of these PCV2-variants it was concluded that PCV2 primarily infects through close contact and nose-to-nose contact. PCV2 genome sequences were obtained from selected pigs at arrival to the research facility and again when the same pigs developed PMWS. This analysis showed that pigs from PMWS-affected herds developed PMWS caused by the same variant of PCV2 as they carried when entering the research facility. In contrast, pigs from non-affected herds developed PMWS with PCV2-variants identified in pigs from PMWS-affected herds. This was probably connected to at least 103 higher mean serum-titer of PCV2 in pigs from PMWS-affected herds as compared to pigs from non-affected herds at the beginning of the transmission study. The study further showed that pigs able to control the PCV2 infection, as measured by the PCV2-titer in serum, recovered clinically (pigs from PMWS-affected herds) or stayed healthy (pigs from non-affected herds). Like this, pigs with a PCV2 titer below 5 × 108 copies/ml serum during the study period had a chance of recover from the PCV2 infection whereas pigs with PCV2 titers above 5 × 108 copies/ml serum at any time point generally died from PMWS.  相似文献   

4.
The objective of this work was to investigate the susceptibility of rabbits and mice experimentally inoculated with porcine circoviruses type 1 (PCV1) and type 2 (PCV2) to infection and development of disease and/or lesions. Forty six New Zealand rabbits and 50 ICR-CDI mice were both divided into two groups comprising PCVI and PCV2 inoculated animals, and a third group inoculated with non-infected cell culture medium. Rabbits were inoculated intranasally while mice were inoculated intraperitoneally. Clinical signs and body weights were recorded at the start of the experiment and at necropsy. Animals were bled, euthanised and necropsied at days 0, 3, 7, 10, 14 and 20 post-inoculation and samples were collected for histopathological, serological, in situ hybridisation and PCR analysis. No clinical signs or gross and microscopic lesions compatible with PCV2 infections such as those seen in pigs were observed. No presence of PCV2 nucleic acid was detected in rabbits and mice by in situ hybridisation. Only one mouse inoculated with PCV1 seroconverted on day 20 P1. PCV1 and PCV2 genome was detected in serum by PCR in mice inoculated with each porcine circovirus, while rabbits were negative for both viral types. These studies indicated that porcine circoviruses did not cause any disease or microscopic lesions in inoculated rabbits and mice during the experimental period. However, intraperitoneally inoculated mice might have harboured PCV2 in circulation without evidence of viral replication.  相似文献   

5.

Background

Post-weaning multisystemic wasting syndrome (PMWS) associated with PCV2 is one of the most costly diseases currently faced by the swine industry. The development of effective vaccines against PCV2 infection has been accepted as an important strategy in the prophylaxis of PMWS.

Methods

In the present study, a PK-15 cell-adapted formalin-inactivated prototype vaccine candidate was prepared using a strain of PCV2 from China. Inactivation of the virus was accomplished using a standard formalin inactivation protocol. The protective properties of the inactivated PCV2 vaccine were evaluated in piglets. Ten 28-day-old pigs were randomly assigned to two groups, each with five. Group 1 was vaccinated intramuscularly with the inactivated virus preparation; Group 2 received sterile PBS as a placebo. By 28 days post-vaccination (DPV), Groups 1 and 2 were challenged intranasally and intramuscularly with 5 × 107 TCID50 of a virulent PCV2 isolate.

Results

The vaccinated pigs seroconverted to PCV2 and had high levels of serum antibodies to PCV2 at 28 days after vaccination, whereas the control pigs remained seronegative. No significant signs of clinical disease were recorded following the challenge with PCV2, but moderate amounts of PCV2 antigen were detected in most lymphoid organs of the control pigs. PCV2 was detected in two out of the five vaccinated pigs. Furthermore, pathological lesions and viremia were milder in the vaccinated group.

Conclusions

The obtained results indicate that the inactivated PCV2 virus vaccine with an oil adjuvant induce an immunological response in pigs that appears to provide protection from infection with PCV2. The vaccine, therefore, may have the potential to serve as a vaccine aimed to protect pigs from developing PMWS.  相似文献   

6.

Background

Porcine circovirus type 2 (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) have been present for the last 2 decades in Croatia, causing large economical losses in the pig production. The clinical features of the infections are mostly manifested by the development of respiratory problems, weight loss and poor growth performance, as well as reproductive failure in pregnant sows. Even though the infections are continuously recognized in some regions in Croatia, the heterogeneity of the detected viral strains from 2012 has not yet been investigated. The objective of this study was to compare virus strains of PCV2 and PRRSV detected until 2008 in Croatia with strains isolated in 2012 to gain a better epidemiological understanding of these two infections.

Results

PCV2 and PRRSV strains detected in 2012 in fattening pigs from regions where these two diseases have been previously described were compared to strains that have been detected in the same regions within the past two decades. The phylogenetic analysis revealed that the circulating PCV2 and PRRSV strains are distantly related to the previously described Croatian viral strains. However, when compared to known isolates from the GenBank a high genetic identity of PRRSV isolates with isolates from Hungary, Denmark and the Netherlands was found.

Conclusion

The results of this study reveal that even though PCV2 and PRRSV are constantly present in the investigated regions in Croatia, the viral strains found in 2012 genetically differ from those detected in earlier years. This indicates that new entries into the pig population appeared with regard to both infections, probably as a result of pig trade.  相似文献   

7.
The objective of this study was to determine the effect of porcine reproductive and respiratory syndrome virus (PRRSV) infection on porcine circovirus type 2 (PCV2) subtypes a (PCV2a) or b (PCV2b) viremia and shedding characteristics in oral, nasal and fecal samples in experimentally infected pigs. Twenty-three, 2- to 6-week-old pigs were randomly divided into five groups: negative control (n=3), PCV2a-I (n=5), PCV2a-PRRSV-CoI (n=5), PCV2b-I (n=5), and PCV2b-PRRSV-CoI (n=5). Blood, oral, nasal and fecal swabs were collected in regular intervals from day post inoculation (dpi) 0 until dpi 70 and tested by quantitative real-time PCR for the presence and amount of PCV2 DNA and by ELISA for the presence of PCV2-specific antibodies. The results indicate that there were significantly (P<0.05) higher loads of PCV2a and PCV2b DNA in serum, oral swabs, nasal swabs and fecal swabs and a higher prevalence of detectable PCV2 antigen in tissues of pigs concurrently infected with PCV2 and PRRSV compared to pigs singularly infected with PCV2 further confirming that PRRSV enhances replication of PCV2. Moreover, PRRSV infection significantly prolonged the presence of PCV2 DNA in serum and increased the amount of PCV2 DNA in oral and nasal secretions and fecal excretions in the later stages of infection between dpi 28 and 70. Shedding patterns were similar between groups infected with PCV2a and PCV2b, indicating that there was no subtype-specific interaction with the PRRSV isolate used in this study. The results from this study highlight the interaction between PRRSV and PCV2 and the importance of controlling PRRSV infection in order to reduce PCV2 virus loads in pig populations.  相似文献   

8.
We previously reported that prior porcine circovirus type 2 (PCV2) infection potentiates the severity of clinical signs, lung lesions, and fecal shedding and tissue dissemination of Salmonella enterica serovar Choleraesuis in infected pigs. Here, we evaluated whether PCV2 vaccination is effective in reducing fecal shedding and tissue dissemination of S. Choleraesuis and improving clinical signs associated with PCV2 and S. Choleraesuis infection in 15 Cesarean-derived, colostrum-deprived pigs randomly assigned to 3 groups (n = 5/group). The vaccinated and co-infected (VAC-COINF) group received 2 ml of a commercial PCV2 vaccine at age 3 weeks. The VAC-COINF and co-infected (COINF) groups were inoculated intranasally with PCV2 and S. Choleraesuis at 5 and 7 weeks of age, respectively. The CONTROL group pigs received a similar volume of PBS for sham-vaccination and sham-inoculation. PCV2 vaccination clearly reduced PCV2 DNA load in the serum and postmortem tissue samples and decreased PCV2 antigen levels in tissue samples of the VAC-COINF group. After S. Choleraesuis infection, the incidence of several clinical signs increased in the VAC-COINF group compared to that in the COINF group. The microscopic lung lesions and weight gain, fecal shedding and tissue dissemination of S. Choleraesuis except in the spleen were not significantly different in the VAC-COINF and COINF groups. Thus, PCV2 vaccination reduced PCV2 in the S. Choleraesuis and PCV2 coinfection model and the effects on S. Choleraesuis were minimal.  相似文献   

9.
Replication of porcine circovirus type 2 (PCV2) in pigs, as measured by spliced capsid mRNA (Cap mRNA) and viral DNA, was investigated following experimental infection. Peripheral blood mononuclear cells (PBMCs), and tissue from bronchial lymph nodes (BLN), inguinal lymph nodes (ILN), tonsils, lungs, liver, kidneys, spleen and thymus from infected pigs on different days post-infection (DPI) were assessed. PCV2 replication differed dramatically between tissues from the same infected pig. The virus actively replicated in most tested tissues at 14DPI in association with increased PCV2 associated lesions and PCV2 antigen levels, although no clinical signs correlated with PCV2 associated disease were observed in infected pigs during the course of the study. The PCV2 Cap mRNA was detected only at 13DPI in PBMCs from infected pigs, suggesting replication of the virus in circulating blood is transient and not a major site for PCV2 replication in vivo. Evaluation of the Cap mRNA and viral DNA synthesis in T and B lymphocyte and monocyte populations from PBMCs and BLN at various intervals post-inoculation revealed replication of PCV2 in all cell subpopulations; however, viral replication in B lymphocytes was greater than observed in mononuclear cells isolated from BLN at 14DPI indicating that B lymphocytes may be an important cell population for PCV2 replication. These findings further our understanding of the cell types permissive for PCV2 replication and the pathogenesis of PCV2 infection in vivo.  相似文献   

10.
天津及周边地区猪圆环病毒2型流行情况调查及分离鉴定   总被引：1，自引：1，他引：0  
为了调查天津及周边地区猪圆环病毒2型（porcine circovirus type 2,PCV2）的感染情况及其分子特征,本研究应用PCR方法对疑似PCV2感染病例开展调查,将阳性病料接种dulac细胞分离病毒,应用PCV2 ORF2基因特异性引物对分离的PCV2进行PCR扩增,克隆、测序后进行核苷酸序列同源性分析。结果显示,不同地区PCV2的阳性率为25.0%~38.1%,其中夏季的阳性率明显高于其他3个季节,达到44.0%;不同阶段猪群中,育肥猪群的PCV2阳性率最高,而哺乳母猪相对较低。经细胞分离得到24株PCV2,其ORF2序列与GenBank中PCV2序列的同源性为87.8%~99.2%,24株分离株之间的同源性为89.4%~100.0%;遗传进化分析显示,24个分离株归属于2个分支。对其中一株分离毒株（Y16155-1株）的体外增殖特性研究表明,第4代接种dulac细胞后6 h即可检出PCV2核酸,72 h病毒含量达到高峰,病毒滴度为10-4.3 TCID50/0.2 mL。本试验结果为进一步研究该地区PCV2分子流行病学及相关疾病的免疫防控奠定了基础。  相似文献   

11.
为了解吉林地区猪细环病毒(TTSuVs)与II型猪圆环病毒(PCV2)混合感染情况,分析TTSuVs感染与仔猪多系统衰竭征(PMWS)的相关性。试验通过PCR技术对2019年收集到的吉林部分地区的10家规模化猪场130份血清样本进行检测;并应用本实验已建立的PCV2、TTSuVs实时荧光定量PCR检测方法,对PCV2阳性样品进行病毒载量的分析,区分PMWS病猪与PCV2亚临床感染猪,比较PMWS病猪与PCV2亚临床感染猪中TTSuVs的载量。结果显示:TTSuV1感染率为38.46%;TTSuV2感染率为57.69%;PCV2感染率为46.15%;TTSuV1与TTSuV2的混合感染率为31.54%;TTSuV1与PCV2的混合感染率为32.30%;TTSuV2与PCV2的混合感染率为44.62%;三种病毒的混合感染率为22.30%。且PMWS病猪血清中TTSuV2载量明显高于PCV2亚临床感染猪(P<0.01)。结果表明,TTSuV2载量与PMWS病的发生存在一定程度的相关性。  相似文献   

12.
The objective of this study was to evaluate the effect of porcine circovirus type 2 (PCV2) vaccines on PCV2-viremic and -seropositive piglets born from naturally PCV2-infected sows against postnatal PCV2 challenge. The experimental design was aimed at mimicking commercial swine rearing conditions to evaluate the response of the PCV2 vaccine on PCV2-viremic and -seropositive piglets after experimental PCV2 challenge. PCV2a (or 2b)-viremic piglets received a PCV2 vaccine at 21 days of age followed by a PCV2b (or 2a) challenge at 49 days of age (28 days post vaccination). The PCV2 vaccines elicited a high level of humoral (as measured by immunoperoxidase monolayer assay and neutralizing antibody titers) and cellular (as measured by the frequency of PCV2-specific interferon-γ-secreting cells) immune response in the PCV2-viremic piglets after vaccination even in the presence of maternally derived antibodies (MDA). The initial infection of PCV2 in the pigs was not affected by PCV2 vaccination, however the challenging PCV2 was reduced by PCV2 vaccination on PCV2-viremic pigs. The results from this study demonstrate that the PCV2 vaccine used in this study is effective at reducing PCV2 viremia and lymphoid PCV2 DNA, even for PCV2-viremic pigs with passively acquired MDA at the time of vaccination.  相似文献   

13.
Porcine circovirus type 2 (PCV2) is a single-stranded circular DNA virus infecting domestic pigs worldwide. Interaction of this virus with the immune system apparently modulates the immune response of the host. In the present study, the implication of different components of PCV2 in the modulation of the immune response of the host were investigated by using PCV2 viral-like particles (VLPs) and 16 novel oligodeoxyribonucleotides containing CpG motifs (CpG-ODNs) based on the PCV2 genomic sequence. The role of these viral components was studied by evaluating the cytokine profiles (IFN-alpha, IFN-gamma, IL-10, IL-2 and IL-12) on porcine peripheral mononuclear cell (PBMC) and bone marrow-derived dendritic cell (BMDC) cultures. Also, the effect of PCV2 and its elements were examined in recall antigen (pseudorabies virus, PRV) responses. While PCV2 was a potent inducer of IL-10 by PBMCs, such effect was not observed using CpG-ODNs or VLPs. However, IFN-gamma and IL-2 production by recall antigen was repressed in presence of PCV2 and most of the studied CpG-ODNs. VLPs did not have such repressive effect. In BMDC cultures, PCV2 and most of CpG-ODNs were able to inhibit IFN-alpha secretion induced by PRV. Interestingly, CpG-ODNs with inhibitory effect were located within the PCV2 Rep gene. Additionally, PCV2 virus was a very strong IL-12 inducer in BMDC cultures. Whereas, IFN-alpha modulation on BMDC after PCV2 VLP treatment was neglectable, PCV2 VLPs were potent IL-12 inducers. Our data shows that PCV2 viral elements can distinctly regulate cytokine production depending on the cell population studied. Thus, the final immune response upon PCV2 infection seems to depend on the fine balance between the regulatory elements present in viral DNA and structural protein within the host immune system.  相似文献   

14.
Long-term PCV2 infection and/or concurrent infection with genotypes PCV2a and PCV2b may play a role in the development of clinical porcine circovirus-associated disease (PCVAD). To evaluate this premise, 24 11-week-old specific pathogen-free (SPF) pigs were randomly assigned to 1 of 4 treatments: negative controls, a single inoculation with PCV2a, single inoculation followed by re-inoculation with a homologous PCV2a strain, or repeated inoculations with heterologous strains (PCV2a, PCV2b). Pigs were evaluated for clinical signs daily through 140 days post inoculation (dpi). Serum samples were collected every other day from dpi 0 through 14 and weekly thereafter. PCV2-inoculated pigs were viremic by dpi 2 and 13 of 18 pigs remained viremic at 140 dpi. No statistical differences in the onset, level, or duration of PCV2 viremia were detected among treatment groups. Anti-PCV2 antibodies were detected between 14 and 28 dpi and were present through 140 dpi without statistical differences in antibody response among treatment groups. In the current study, pigs had extended viremia combined with detectable tissue PCV2 antigen levels despite the presence of high levels of anti-PCV2 antibody; however, no clinical disease was observed.  相似文献   

15.
The aim of this study was to evaluate the protective efficacy of the CIRCOQ porcine circovirus type 2 (PCV2) subunit vaccine in piglets with high maternally derived antibodies (MDAs) against disease caused by natural infection with PCV2d. A total of 130 weaned, 21-day-old healthy pigs was allocated into 3 trial groups. The signs of respiratory disorder were higher in unvaccinated pigs than in vaccinated pigs at 13 to 17 weeks old (P < 0.05), 18 to 22 weeks old (P < 0.001), and 23 to 27 weeks old (P < 0.01). The unvaccinated pigs had an early rate of dermatitis at 8 to 12 weeks old (10.0%), 13 to 17 weeks old (30.0%), 18 to 22 weeks old (46.7%), and 23 to 27 weeks old (33.3%), while there were no cases of dermatitis in vaccinated pigs. There was a significant difference (P < 0.05) in the mortality of pigs in the unvaccinated group and the 2-dosed vaccinated group. PCV2 viremia was detected in the blood and peaked at 105 days old in both unvaccinated pigs (Ct-adj = 8.40) and pigs vaccinated with 1 dose (Ct-adj = 6.37), while no detectable PCV2 virus was found in the blood of pigs vaccinated with 2 doses. At 77 and 105 days old, the PCV2 viremia load (Ct-adj) of unvaccinated pigs and those vaccinated with 1 dose was significantly higher (P < 0.05) than that of the 2-dosed vaccinated pigs. The body weight (BW), average weight gain (AWG), and average daily gain (ADG) in both groups of vaccinated pigs were significantly higher (P < 0.05) than those of unvaccinated pigs. The study vaccine was significantly efficacious in protecting vaccinated pigs against clinical symptoms, blood viral load, and mortality, as well as improving productivity, compared with unvaccinated pigs.  相似文献   

16.
This study was aimed to establish a duplex nanoparticle-assisted PCR (nano-dPCR) method for the simultaneous detection of porcine circovirus type 2 (PCV2) and PCV3, and to apply this method in the detection of PCV2 and PCV3. Primers specific to PCV2 and PCV3 were designed by reference to the respective gene sequences in GenBank. The reaction conditions of nano-dPCR were also optimized. An evaluation of the specificity and sensitivity of the established nano-dPCR protocol proved the method to be both specific and sensitive, with the lower detection limit for the amount of nucleic acid in PCV2 and PCV3 to be 93.2 and 91.6 copies/μL, respectively. This sensitivity was 100 times higher than that of conventional PCR. The method was applied to inspect 265 clinical samples sent for testing, and the results showed that PCV2 and PCV3 infection in pig was rather common, with 16.6% positive for PCV3, 14.7% positive for PCV2, and 6.8% for mixed infection. The detection results on clinical samples supported the newly established nano-dPCR method as a rapid and sensitive differential diagnosis for the early infection of PCV2 and PCV3.  相似文献   

17.
本研究旨在建立一种同时检测猪圆环病毒2型（PCV2）和猪圆环病毒3型（PCV3）的双重纳米PCR（nano-dPCR）方法,同时应用该方法对PCV2和PCV3进行检测。参考GenBank中登录的PCV2和PCV3型基因序列分别设计特异性引物,对nano-dPCR的反应条件进行优化;同时考察所建立的nano-dPCR检测方法的特异性和敏感性。结果显示,所建方法的特异性和敏感性良好,对PCV2和PCV3两种病毒的最低核酸检测量分别为93.2和91.6拷贝/μL,其敏感性比普通PCR高100倍。应用该方法对送检的265份临床样本进行检测,结果显示,PCV2和PCV3在猪群中存在普遍感染,PCV3和PCV2的阳性率分别为16.6%和14.7%,混合感染阳性率为6.8%。临床样品的检测结果表明,本试验建立的nano-dPCR方法为PCV2和PCV3早期感染进行快速、敏感鉴别诊断提供了新方法。  相似文献   

18.
猪繁殖与呼吸道综合征(PRRS)和猪圆环病毒2型(PCV2)是近几年来严重危害猪群的两大免疫抑制性疾病。为了解这两种疾病在宜宾市的流行情况,我们采集了宜宾市12个适度规模的养殖场共计329份未经两种疫苗免疫的血清进行了调查。结果显示PRRSV血清抗体阳性率为31.8%,PCV2阳性率为28.6%,两种病混合感染率21.9%,说明这两种病在宜宾市流行比较严重。  相似文献   

19.
应用本实验室构建的嵌合型猪圆环病毒（PCV1—2）及真核表达质粒pcDNA3．1／V5-His-ORF2作为免疫原免疫母源抗体ELISA效价在0．07～0．60不等的商品猪,9头猪随机分为4组,1组（3头）肌肉注射免疫10^3.5 TCID50的PCV1-2／头,2组（2头）肌肉注射真核表达质粒200μg／头,3组（2头）肌肉注射空载体（pcDNA3．1）200μg／头,4组（2头）不免疫作为攻毒对照组。于免疫后42d,PCV1—2组及真核表达质粒组产生了PCV2抗体。免疫后42d所有组攻毒PCV2和PRRSV,剂量分别为2×10^4.5 TCID50／头和10^6 TCID50／头。攻毒后21d,攻毒对照组猪淋巴结比免疫组显著肿大,免疫组猪血清、淋巴结中PCV2病毒栽量低于对照组,攻毒对照组猪淋巴结中PCV2抗原含量高于免疫组。这些结果表明,嵌合型PCV1-2及真核表达质粒肌肉注射免疫商品猪后,对PCV2感染能产生保护性免疫应答,有可能成为候选疫苗。  相似文献   

20.
Information regarding the susceptibility of swine lymphocytes to PCV2 is rather limited. To further explore and characterize the PCV2 infection in swine lymphocytes, an in vitro model using concanavalin A (Con A)-stimulated peripheral blood lymphocytes (PBLs) obtained from clinically healthy PCV2-carrier pigs was introduced. It was found that the PCV2 antigen-containing rate was below 2% in PBLs from healthy PCV2-free pigs following treated simultaneously with Con A and PCV2. However, significantly higher PCV2 antigen- and nucleic acid-containing rates could be seen in Con A-stimulated PBLs from clinically healthy PCV2-carrier pigs. Prior to Con A treatment, both of the PCV2 antigen- and nucleic acid-containing rates in PBLs from healthy PCV2-carrier pigs were less than 1%; however, they reached 22.1+/-5.7% by flow cytometry and 27.1+/-6.5% by in situ hybridization, respectively, at 4-day post-incubation with Con A. Phenotyping of PCV2 antigen-containing cells revealed that PCV2-positive cells could be detected in both T and B lymphocyte populations within which IgM-positive B lymphocytes appeared to have a relatively higher positive rate. The Con A-stimulated PBLs also displayed a significantly higher viral load by the measurement of either PCV2 DNA copy number or viral titer when compared with the non-treated PBLs from healthy PCV2-carrier pigs. The results indicate that PBLs, especially IgM-bearing B lymphocytes, are indeed susceptible to PCV2 infection and PCV2 is capable of replicating in dividing lymphocytes. This activation-induced replication may explain in part the pathogenesis of lymphoid depletion in PMWS-affected pigs.  相似文献   

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