A molecular survey reveals high occurrence of co-infections in intensive pork production farms with increased rates of mummified swine fetuses in Southern Brazil / [Pesquisa molecular revela alta ocorrência de coinfecções em granjas de produção intensiva de suínos com altas taxas de mumificação fetal no sul do Brasil]

Neste estudo, 308 amostras de fetos mumificados foram testadas para parvovírus suíno (PPV), circovírus suíno tipos 2 e 3 (PCV2 e PCV3) e leptospiras patogênicas. A idade gestacional no momento da perda gestacional e a frequência da mumificação fetal de acordo com a ordem de parto também foram investigadas. As amostras foram coletadas em granjas comerciais de criação de suínos da região sul do Brasil que apresentassem taxas de mumificação fetal igual ou maiores a 2,5%. Fragmentos de pulmão, rim, fígado e coração de fetos suínos mumificados foram coletados para análise molecular. Resultados da PCR foram classificados de acordo com a região de origem das amostras, tendo Santa Catarina, Paraná e Rio Grande do Sul contabilizado 87 (28,25%), 89 (28,90%) e 132 (42,86%) do total de amostras de fetos suínos mumificados, respectivamente. Coinfecções foram observadas na maioria dos casos e PCV3 foi o agente mais prevalente detectado, encontrado em 298 amostras (96,75%). A maioria das perdas gestacionais foi observada entre 50 e 70 dias de gestação (168; 54,5%) e a mumificação fetal não foi associada à ordem de parto das matrizes. Os achados sugerem que as altas taxas de fetos suínos mumificados na região Sul do Brasil podem ser explicadas pela infecção com esses agentes virais.(AU)

First detection and genetic characterization of porcine parvovirus 7 from Korean domestic pig farms

Porcine parvovirus 7 (PPV7) was first detected in Korean pig farms in 2017. The detection rate of PPV7 DNA was 24.0% (30/125) in aborted pig fetuses and 74.9% (262/350) in finishing pigs, suggesting that PPV7 has circulated among Korean domestic pig farms. Phylogenetic analysis based on capsid protein amino acid sequences demonstrated that the nine isolated Korean strains (PPV-KA1-3 and PPV-KF1-6) were closely related to the previously reported USA and Chinese PPV7 strains. In addition, the Korean strains exhibit genetic diversity with both insertion and deletion mutations. This study contributes to the understanding of the molecular epidemiology of PPV7 in Korea.

Evaluation of safety and immunogenicity of a new octavalent inactivated vaccine containing porcine parvovirus, erysipelas, and leptospira

Porcine parvovirus, Erysipelothrix (E.) rhusiopathiae, and Leptospira (L.) interrogans are considered major etiologic agents of reproductive failure in pigs, causing economic loss in the swine industry. In this study, the safety and immunogenicity of a new octavalent inactivated vaccine were evaluated. The vaccine contained inactivated porcine parvovirus, E. rhusiopathiae, and six L. interrogans serovars (Bratislava, Canicola, Grippotyphosa, Hardjo, Icterohaemorrhagiae, and Pomona). Safety test results showed no notable side effects or clinical signs after vaccination in mice, guinea pigs, and sows. In addition, we assessed immunogenicity of the vaccine in 25 sows under field conditions. The vaccinated group (n = 20) had a significantly higher antibody level than the non-vaccinated group (n = 5). Moreover, the stillbirth rate decreased in piglets born from vaccinated sows, resulting in an increased fertility rate. The results of this study demonstrate that the new octavalent inactivated vaccine can be applied safely and effectively to improve reproductive performance in sows.

Immune Response of Recombinant Pseudorabies Virus rPRV-VP2 Expressing VP2 Gene of Porcine Parvovirus in Mice / 病毒学报

In order to develop a combined live vaccine that will be used to prevent against porcine parvovirus (PPV) and Pseudorabies virus (PRV) infection, the VP2 gene of PPV was inserted into the transfer vector plasmid pG to produce the recombinant plasmid pGVP2. The plasmid pGVP2 and the genome of PRV HB98 attenuated vaccine were transfected by using lipofectamine into swine testis cells for the homologous recombination. The recombinant virus rPRV-VP2 was purified by selection of green fluorescence plaques for five cycles. 6-week-old female Kunming mice were immunized intramuscularly with attenuated PRV parent HB98 strain, commercial inactivated vaccine against PPV, recombinant virus, DMEM culture solution. The injections were repeated with an equivalent dose after 2 weeks in all of the groups, and then challenged with the virulent PRV NY strain at 7 weeks after the first immunization. The recombinant virus rPRV-VP2 was successfully generated, and the recombinant virus could effectively elicite anti-PPV and PRV antibody and significant cellular immune response as indicated by anti-PPV ELISA and HI, PRV-neutralizing assay and flow cytometry. The challenge assay indicated that recombinant virus could protect the mice against the virulent PRV challenge. These results demonstrated that the recombinant virus can be a candidate recombinant vaccine strain for the prevention of PRV and PPV.

Proliferation characteristics of a PK-15 cell-adapted strain of porcine parvovirus / 病毒学报

To study the proliferation characteristics of PPV in differently infected way and the variance of concentrations in different cells. A strain of porcine parvovirus(PPV) was adapted to PK-15 cells, and a Real-time fluorescent quantitative PCR (FQ-PCR) assay was developed based on the specific region of the NS1 gene of PPV to quantify the PPV. The FQ-PCR was used to measure the viral concentration of virus-infected cells by simultaneous or step by step inoculation and plot one-step growth curves. The proliferation characteristics of PPV strain in different cells lines (HeLa, MDBK, PK-15 ,ST, F81, BHK-21 and Marc-145) was also compared. The results showed the PK-15 cell -adapted strain of PPV produced CPE after 12 passages, and maintained stable CPE at the following 10 messages. The one-step growth curve showed that the virus concentration of simultaneous inoculation was higher than that of the step-by-step inoculation, and the proliferation cycle of step-by-step inoculation was shorter. The proliferation ability of PPV strain in different cells showed that CPE appeared first inPK-15, followed by ST, HeLa and MDBK, and the virus concentration was highest in ST, followed byPK-15, MDBK and HeLa. NO proliferation was observed in F81, BHK-21 and Marc-145 cells. These findings lay a material foundation for the basic researches on PPV and the development of vaccine.

Interstitial nephritis of slaughtered pigs in the State of Mato Grosso, Brazil / Nefrite intersticial em suínos abatidos no Estado de Mato Grosso

This study evaluated histological lesions in kidney samples from pigs with nephritis in two slaughterhouses in the State of Mato Grosso, Brazil. Four hundred samples were subjected to histology, anti-porcine circovirus type 2 (PCV2) immunohistochemistry (IHC), anti-Leptospira sp. immunofluorescence (IF), and polymerase chain reaction (PCR) for PCV2, porcine parvovirus (PPV), and Torque teno virus type 1 and 2 (TTV1, TTV2) detection. Histological lesions were found in 81% of the samples, and mononuclear interstitial nephritis was the most frequent lesion (77.50%). A follicular pattern was observed in 40.97% of the interstitial nephritis lesions. PCV2, PPV, TTV1, and TTV2 were identified in the kidneys by PCR in 27.25%, 28.50%, 94%, and 87.5% of the samples, respectively. Leptospira sp. was not detected through IF. Infection by PCV2 (PCR) and the presence of histological lesions (P=0.008) and giant cells (P=0.0016) were significantly associated. An association was observed between the TTV2-TTV1 co-infection (P<0.0001) and the risk for pathogenesis. These findings indicated that PCV2, PPV, TTV1, and TTV2 were widely distributed among pigs in the local farms and that the presence of these agents should be considered in the differential diagnosis of kidneys with interstitial nephritis in pigs.

O propósito desse estudo foi avaliar as lesões histológicas observadas em rins condenados por nefrite pelo Serviço de Inspeção Federal, em dois frigoríficos de Mato Grosso, Brasil. Foram coletados 400 rins condenados por nefrite e submetidos aos exames de histologia, imuno-histoquímica (IHC) para Circovirus suíno Tipo 2 (PCV2), imunofluorescência direta (IF) para Leptospira sp. e reação em cadeia pela polimerase (PCR) para detecção de PCV2, Parvovirus suíno (PPV) e Torque teno vírus Tipo 1 e 2 (TTV1 e TTV2). Foram observadas lesões histológicas em 81% das amostras, sendo nefrite intersticial mononuclear a mais freqüente (77,50%). Das lesões de nefrite intersticial encontradas, 40,97% apresentaram padrão folicular. Através da PCR foi observada ampla distribuição dos agentes (PCV2, PPV, TTV1 e TTV2) nas propriedades e municípios, com ocorrência de 27,25%, 28,50%, 94% e 87,50%, respectivamente. Leptospira sp. não foi detectada através da IF. Houve associação significativa da infecção do PCV2 com presença de lesão histológica (P=0,008) e de células gigantes (P=0,0016). Também houve associação entre a co-infecção TTV2 e TTV1 (P<0,0001). Esses achados indicam que os vírus PCV2, PPV, TTV1 e TTV2 devem ser considerados no diagnóstico diferencial de rins com nefrite intersticial em suínos.

Eukaryotic expression of NS1 major antigen region of PPV and development of an indirect ELISA based on the expressed protein / 病毒学报

To construct secretory expression vector of PPV NS1 gene, the fragment of PPV NS1 gene coding for major antigen region of the NS1 protein was amplified by PCR and inserted into multiple clone site of eukaryotic expression vector pPICZalpha-A. The recombinant pPICZalpha-A-NS1 plasmid was transferred into P. pastoris strain GS115 mediated by electro transform. Recombinant P. pastoris strain GS115 was induced to express the fusion protein by methanol. The expressed and purified protein was analyzed by SDS-PAGE and Western Blot. The recombinant protein was highly-expressed and showed a good immunoreactivity. The indirect ELISA method was developed for detecting antibodies against PPV by checkerboard titration assay. The result showed that the optimal concentration of coated antigen was 3.2 microg/mL and the best dilution of serum was 1 : 80. The positive cut-off value of the ELISA assay was OD450 > 0.4 and OD450 positive serum/OD450 negative serum > 2.0. Compared with HI and commercial ELISA kits, the assay revealed 94.2% and 92.1% agreement respectively. The assay demonstrates good specificity and sensitivity, and can be applied in the detection of porcine parvovirus.

Zearalenone Affects Immune-Related Parameters in Lymphoid Organs and Serum of Rats Vaccinated with Porcine Parvovirus Vaccine

Rats were administered zearalenone (ZEA) via gavage at dosages of 0, 1, 5, and 30 mg/kg for 36 days. On treatment day 8, inactivated porcine parvovirus vaccine (Vac) was injected intraperitoneally. Antibody production against porcine parvovirus was then measured as a function of ZEA treatment. Compared to the vaccine alone, ZEA treatment, with or without Vac, decreased the serum level of IgG. The level of IgM decreased in all ZEA groups at day 22, but the decrease was sustained only in the medium-dose ZEA group at day 36. The level of IgA was unchanged in the Vac only and ZEA groups at day 22, but was decreased in the 5 mg/kg ZEA plus Vac group compared to the Vac only group at day 36. The level of IgE was decreased by all doses of ZEA at day 22, but was unaffected in ZEA plus Vac groups compared to the Vac only group. The levels of IL-1 in the thymus and spleen; INF-gamma in serum; IL-2, IL-6, and IL-10 in the thymus; and IL-10 and IFN-gamma in the spleen decreased after ZEA administration. Furthermore, the levels of IL-1beta in the spleen and mesenteric lymph node, IL-1beta in the thymus, IL-2 in the thymus and spleen, IL-6 in the thymus, IL-10 and IFN-gamma in the spleen, and GM-CSF and TNF-alpha in the thymus decreased after vaccination in rats exposed to ZEA. In conclusion, these results suggest that ZEA exposure via drinking water can cause an immunosuppressive effect by decreasing immunoglobulins in serum and cytokines in lymphoid organs.

Prevalence of porcine parvovirus in pigs with postweaning multisystemic wasting syndrome in Jeju Island / 대한수의학회지

Postweaning multisystemic wasting syndrome (PMWS), which was first identified in western Canada in 1991 and more recently in the United States, Europe and Asia, is an emerging disease in pigs. Porcine circovirus type 2 (PCV-2) is the primary infectious viral agent causing PMWS, but the full expression of the disease may require the presence of other agents. It is reported that there is apparent synergism between PCV-2 and porcine parvovirus (PPV) in increasing the severity of the clinical signs and lesions of PMWS. From January 2006 to May 2008, a total of the 154 lymph node samples were collected from 4~12 weeks old pigs which had been submitted to the College of Veterinary Medicine, Jeju National University, Korea. These pigs were diagnosed as PMWS on the basis of clinical and pathological examination from 48 commercial herds in Jeju Island. Based on the immunohistochemistry, porcine parvovirus was detected in 69 cases (44.8%) from 154 weaned or grower pigs. PPV antigens were detected in the cytoplasm of histiocytic cells multifocally infiltrated in the cortex and paracortex of lymph nodes. The results of this study clarify that PPV is prevalent in pigs with PMWS on Jeju Island. Therefore PPV is one of the most important co-agents in the development of naturally acquired PMWS. This study may be helpful to the control of this disease and to epidemiological aspects.

Construction and immunogenicity of recombinant porcine parvovirus-like particles with somatostatin / 生物工程学报

In order to obtain a virus-like particle vaccine both for porcine parvovirus (PPV) prevention and growth-promotion, VP2 gene of PPV NJ-a strain was amplified with PCR, and four copies of synthetic somatostatin gene were fused to the N-terminal of VP2 gene. The fused gene was cloned into pFast-HT A to construct the recombinant plasmid pFast-SS4-VP2, then the pFast-SS4-VP2 was transformed into DH10Bac competent cells and recombined with shuttle vector Bacmid, followed by identification with blue-white screening and PCR analysis for three cycles, and the positive recombinant was named as rBacmid-SS4-VP2. The positive Sf-9 cells were transfected with rBacmid-SS4-VP2 by Lipofectamine to produce recombinant baculovirus. When the cytopathic effect (CPE) was obvious, the transfected Sf-9 cell was harvested, and the positive recombinant virus was named as rBac-SS4-VP2. The insertion for the target gene into baculovirus genome was confirmed with PCR. SDS-PAGE and Western blotting revealed that the calculated protein of approximately 68 kDa was in the expressed in the insect cells. The Sf-9 cells infected with rBac-SS4-VP2 were stained positive against PPV antibody using the indirect immunofluorescence assay (IFA). Moreover, the virus particle self-assembly was observed under electron microscopy. 90 four-week-old mice were immunized by the recombinant protein coupled with different adjuvants alhydrogel, IMS and oil. VP2-specific ELISA antibodies, PPV-specific neutralizing antibody, somatostatin antibody and growth hormone levels were examined to evaluate the immunogenicity of this virus like particle. Results indicated that mice groups immunized rSS4-VP2 protein with alhydrogel and IMS developed similar humoral immune response comparing with inactived PPV vaccine. Mice group immunized with rSS4-VP2 generated higher level of SS antibody and growth hormone comparing with negative control, mice receiving rSS4-VP2 with alhydrogel developed the highest antibody titre than all other groups, while the oil group developed the lowest antibody level. This study provides not only a new rout for production of safe and effective virus like particle subunit vaccine, but also the foundations for peptide presentation and multivalent subunit vaccine design.

Identification of Porcine parvovirus from wild boars by partial sequencing of the VP-2 coding gene / Identificação de parvovírus suíno em javalis a partir do sequenciamento parcial do gene VP-2

Este estudo descreve a detecção e a identificação de DNA de parvovírus suíno (PVS) em amostras de órgãos de dois javalis, por PCR e sequenciamento direcionado ao gene VP-2. Pools de órgãos (baço, rins, fígado, linfonodos e tonsila) de três javalis adultos e assintomáticos de Paraguaçu Paulista, SP, criados com propósitos comerciais, foram submetidos à detecção de PVS, resultando em duas amostras positivas após reações de nested-PCR direcionadas aos genes NS-1 e VP-2. Os fragmentos parciais de VP-2 foram sequenciados e comparados a sequências homólogas de cepas NADL-2 e Kresse, demonstrando identidade nucleotídica de 100%. Com relação a 29 cepas de PVS previamente isoladas no Brasil, o grau de identidade nucleotídica variou de 99 a 100% (uma a três substituições de nucleotídeos). Estes resultados demonstram, pela primeira vez, a detecção direta por PCR de parvovírus suíno em javalis, confirmada por análise de sequenciamento genético.

Ocorrência de infecção por parvovírus suíno e gastrenterite transmissível em suínos, criados de forma extensiva, em Goiás / Occurrence of porcine parvoviral infection and transmissible gastroenteritis virus infection in swine from extensive raising systems in the state of Goiás, Brazil

The serological status of porcine parvovirus (PPV) infection and transmissible gastroenteritis virus (TGEV) infection were determined in swine from extensive raising systems in the state of Goiás, Brazil. Ninety-seven serum samples were collected from animals in 12 extensive farms distributed in six cities located nearby Goiânia, GO, and 74 samples were collected from animals in a slaughterhouse in Goiânia, GO. For the PPV-specific antibody detection, the hemaglutination inhibition test (HI) was used; and for TGE antibody detection, the serum neutralization test was performed. Results showed that 25 out of the total 171 (14.4%) analyzed sera were positive for PPV antibodies, and the HI titers varied between 256 to 4,096. None of the 136 serum samples analyzed for TGEV was positive. This is probably the first study that detected PPV and TGEV-specific antibodies in swine herd in the state of Goiás. Data suggest that PPV but not TGEV circulated between and among this population of swine in that state.

Molecular basis for porcine parvovirus detection in dead fetuses

Reproductive failures are still common grounds for complaint by commercial swine producers. Porcine parvovirus (PPV) is associated with different clinical reproductive signs. The aim of the present study was to investigate PPV fetal infection at swine farms having ongoing reproductive performance problems. The presence of virus in fetal tissues was determined by nested-polymerase chain reaction assay directed to the conserved NS1 gene of PPV in aborted fetuses, mummies and stillborns. Fetuses show a high frequency of PPV infection (96.4%; n = 28). In 60.7% of the fetuses, PPV were detected in all tissue samples (lung, heart, thymus, kidney, and spleen). Viral infection differed among fetal tissues, with a higher frequency in the lung and heart (p < 0.05). Fetuses with up to 99 days of gestational age and from younger sows showed a higher frequency of PPV (p < 0.05). No significant difference in the presence of PPV was detected among the three clinical presentations. The results suggest that PPV remains an important pathogenic agent associated with porcine fetal death.

Co-infection by porcine circovirus type 2 and porcine parvovirus in aborted fetuses and stillborn piglets in southern Brazil

Porcine circovirus types 1 and 2 (PCV1, PCV2) and porcine parvovirus (PPV) are widespread in pig populations around the world. Nevertheless, only PCV2 has been associated with different clinical syndromes, thus representing a major problem to the pig industry. The association of cases of swine abortions and stillborns with PCV1 and PCV2 and PPV was studied retrospectively (2005-2007). Additional pathogens were also investigated in lesioned fetuses. The studied litters included stillborn piglets and several mummified fetuses of varied sizes. Ventricular dilatation, myocardial pale areas, and mesocolic edema were the gross lesions. Escherichia coli was detected as co-infecting with PCV2 the cases in which mesocolic edema was seen. Microscopic lesions included non-suppurative myocarditis, myocardial necrosis and fibrosis, mineralization foci and intranuclear inclusion bodies in cardiomyocytes, and interstitial mononuclear pneumonia. Samples from 7 (5.78 per cent) of 121 aborted fetuses and stillborn piglets had lesions consistent with a viral cause and showed both positive anti-PCV2 immunostaining as well as PCV2-PCR. In samples from 3 (2.47 per cent) of these 7 fetuses, co-infection with PPV was confirmed by Nested-PCR. Both viruses were detected in fetuses at different stages of gestation. Viral antigens of PCV2 were detected by immunohistochemistry mainly in macrophages and myocytes. PCV1 individually was not detected in any of these affected fetuses, but it was associated with PCV2 and/or PPV in some of them. These findings indicate that PCV2 alone or in association with PPV should be kept in mind when investigating causes of infectious abortion in pigs in Brazil.

Estudou-se retrospectivamente (2005-2007) a associação de casos de abortos e natimortos suínos com infecções por circovírus suíno (PCV) tipos 1 e 2 e parvovírus suíno (PPV). Outros agentes patogênicos foram pesquisados em amostras de fetos com lesões. O estudo incluiu natimortos e fetos mumificados de tamanhos variados. Dilatação ventricular, áreas pálidas miocárdicas e edema de mesocólon foram as lesões macroscópicas observadas. Escherichia coli co-infectou com PCV2 as amostras dos casos com edema de mesocólon. Lesões microscópicas incluíram miocardite não supurativa, necrose e fibrose miocárdicas, focos de mineralização e corpúsculos de inclusão em cardiomiócitos e pneumonia intersticial mononuclear. Entre os 121 fetos suínos abortados ou natimortos analisados, sete (5,78 por cento) tinham lesões compatíveis com origem viral e foram positivos pelas técnicas de imunoistoquímica e PCR para PCV2. Além disso, três (2.47 por cento) desses sete casos também foram confirmados como co-infectados com PPV através da PCR. Antígenos de PCV2 foram observados principalmente em macrógafos e no interior de miócitos dos fetos suínos abortados e natimortos. PCV2 e PPV foram detectados em diferentes estágios de gestação. PCV1 não foi associado isoladamente com feto ou natimorto afetado, mas estava presente em associação com PCV2 e/ou PPV em alguns desses produtos. Esses achados indicam que a infecção por PCV2, isoladamente ou em associação com PPV, deve ser considerada no diagnóstico de aborto infeccioso suíno no Brasil.

The surface display of porcine parvovirus VP2 protein in Lactobacillus casei / 生物工程学报

Lactobacillus casei 393 was selected as a bacterial carrier for the expression of Porcine Parvovirus (PPV) protective antigen VP2 protein. The gene encoding PPV VP2 protein was cloned into the Lactobacillus casei surface expression vector pPG, and then the constructed recombinant vector pPG-VP2 was electrotransformed into Lactobacillus casei 393 generating the recombinant system pPG-VP2/L. casei393 expressing PPV VP2 protein. The recombinant strain was induced by 2% Lactose in MRS and about 74kD protein was detected with SDS-PAGE. The result of Western-blot indicated that the expressed protein possessed the antigenic specificity which could be recognized by mouse anti-PPV serum. The indirect immunofluorescent test showed that the expressed protein was secreted on the cell surface Lactobacillus casei.

Coinfecção experimental de circovírus suíno tipo 2 isolado no Brasil e parvovírus suíno em suínos SPF / Experimental coinfection of SPF pigs with porcine circovirus type 2 isolated in Brazil and porcine parvovirus

Avaliou-se a patogenicidade do circovírus suíno tipo 2 (PCV2) isolado no estado de Santa Catarina mediante coinfecção experimental com parvovírus suíno (PPV). Foram utilizados 24 leitões specific pathogen free (SPF) com cinco dias de idade, distribuídos em quatro grupos (G), alojados em salas independentes e inoculados por via intranasal: G1 - controle (n=4); G2 - inoculados com PCV2 (n=7); G3 - inoculados com PPV (n=6); G4 - inoculados com PCV2 e PPV (n=7). Os animais foram monitorados diariamente para avaliação clínica e necropsiados 48 dias após a infecção. As principais lesões anatomopatológicas observadas nos suínos do G2 e G4 foram: aumento do volume dos linfonodos, depleção linfocitária com redução dos folículos linfóides nos órgãos linfocitários e presença de infiltrado eosinofílico nos linfonodos. A técnica de nested-PCR para PCV2 foi utilizada detectando DNA viral em órgãos de todos os animais do G2 e G4. O PCV2 infectou suínos SPF por via intranasal e foi detectado em outros órgãos, com mais lesões histopatológicas e em maior proporção nos animais coinfectados com PPV (G4), quando comparados aos infectados somente com PCV2 (G2).

The virulence of porcine circovirus type 2 (PCV2) isolated in Santa Catarina State by coinfection with porcine parvovirus (PPV) was investigated. Twenty-four, 5-day-old SPF pigs were distributed into four groups, housed in separate rooms and inoculated by intranasal route: G1 - control (n=4); G2 - inoculated with PCV2 (n=7); G3 - inoculated with PPV (n=6); G4 - inoculated with PCV2 and PPV (n=7). The animals were monitored daily for clinical evaluation and were necropsied 48 days after the infection. The pathological lesions seen in G2 and G4 pigs were: enlargement of lymph nodes, mild to moderate lymphoid cell depletion, affecting lymphoid follicles in lymphoid organs and presence of infiltration by eosinophils in lymph nodes. PCV2 DNA was detected by a nested-PCR in all pigs of G2 and G4. These findings confirmed that pigs were successfully infected intranasally with PCV2. The presence of PCV2 DNA in tissue samples and the pathological lesions were more evident in pigs infected with both PCV2 and PPV than in pigs infected with PCV2 alone.

Construction of the eukaryotic expression vector with IL-2 gene and VP2 gene of PPV and research on immunogenicity / 生物工程学报

To construct gene vaccine of PPV and to investigate the effects of interleukin 2 (IL-2) as an adjuvant on immune responses in mouse, the recombinant expression plasmid of pCIneo-IL2-VP2 was constructed and transfected into PK-15 cells by lipofectamine, the expressed product was detected by immunofluore assay. To study the immune effects of DNA vaccine in vitro and in vivo, mice were used as the animal model. The recombinant plasmid pCIneo-IL2-VP2, the control plasmid pCI-neo and the PPV live vaccine were immunized by intramuscular injection. Anti-PPV antibodies were measured by ELISA, lymphocyte proliferation activity was detected using MTT method, and the specific killing activities of CTL were assayed too. The results show that the immunized mice produced PPV antibody after one week, and reached to highest after four weeks. Compared with the control group, the pCIneo-IL2-VP2 immunized group produced significant differences in the antibody titers, the lymphocyte proliferation activity and the specific killing activities of CTL. The pCIneo-IL2-VP2 induced humoral and cellular immunity responses similarly to that the live vaccine induced. These results manifested that the PPV DNA vaccine successfully induced humoral and cellular immunity response in mice with the IL-2 gene as an adjuvant.

Partial Nucleotide Sequence of Porcine Parvovirus (VRI-1 Strain): Identification of the Putative Defective Genomes

A porcine parvovirus, designated as VRI-1, was isolated from a 30-day-old piglet. Replicative form of viral DNA from ST cells infected with VRI-1 was directly cloned into pUC19. The cloned DNA fragment contained the entire nonstructural and structural protein genes, covering approximately 85% of the viral genome. The nucleotide sequence of VRI-1 showed 99.4~99.5% identity in the nonstructural protein (NS) and 99.0~99.2% identity in the structural protein with previously reported PPV strains, respectively. Among the cloned genes, two types of defective genomes with deletion of 100 and 247 nucleotides at almost similar location of 3' region within NS gene were also identified in this study.

Prevalence of porcine reproductive and respiratory syndrome virus, porcine circovirus type 2 and porcine parvovirus from aborted fetuses and pigs with respiratory problems in Korea

Porcine reproductive and respiratory syndrome virus(PRRSV)0, porcine circovirus type 2(PCV-2) and porcine parvovirus (PPV)0 infections were investigated as possible causes of the postweaning multisystemic wasting syndrome(PMWS). Specific primers for RT-PCR and PCR were designed for the differential detection of PRRSV, PCV-2 and PPV. Using PCR, these viruses were detected in homogenized tissue samples from pigs that had respiratory of reproductive problems in the time period between 1998 and 2000; the overall prevalences were: PRRSV 31.4%, PCV-2 46.5%, and PPV 8.1%. PCV-2 was also detected in aborted fetal tissues.