高级病理学王鹏幻灯片

姓名：王鹏 研究方向：分子病毒与免疫学 * 1高级病理学 猪圆环病毒 -很小很强大 * 高级病理学 2 Contents 1.The virus and the disease 2.The viral genome 3.The viral proteins 4.Replication of PCV 5.Virus import * 高级病理学 4 1. The virus and the disease Porcine circovirus (PCV) was originally identied as a con- taminant of porcine kidney cell cultures (PK-15) . The PCV virion is icosahedral(二十面体） , nonenveloped, and 17nm in diameter （直径） . The genome of PCV is a single-stranded circular DNA of about 1.76 kb. PCV is classied in the genus Circovirus of the Circoviridae family, which consists of other animal circoviruses such as psittacine（鹦鹉） beak-feather disease virus, goose circovirus, canary （金丝） circovirus, and pigeon circovirus(PiCV). * 高级病理学 5 Two genotypes of PCV have been recognized The PK15 cell-derived PCV has been considered to be non-pathogenic to pigs and is designated PCV type 1(PCV1). PCV type 2 (PCV2) is now accepted as the major infectious agent involved in postweaning multisystemic wasting syndrome (PMWS) , a new emerging swine disease worldwide since its occurrence in Canada in 1991. * 高级病理学 6 Postweaning Multisystemic Wasting Syndrome (PMWS) uInfection with porcine circovirus type 2 (PCV2), but not PCV1, has been associated with postweaning multisystemic wasting syndrome (PMWS) in young weaned pigs. u Usually PMWS appears in pigs aged 5 to 18 weeks, and affected pigs show wasting, respiratory distress, enlarged lymph nodes and, occasionally, jaundice and diarrhea . Gross lesions in affected pigs consist of generalized lymph adenopathy in combination with interstitial pneumonia, hepatitis, renomegaly, splenomegaly, and intestinal wall edema Other syndrome 1.porcine dermatitis and nephropathy syndrome,PDNS 2.porcine respiratory disease complex, PRDC 3.proliferative and necrotising pneumonia, PNP 4.congenital tremor AII, CT-AII * 7高级病理学 * 高级病理学 8 2. The viral genome PCVs contain a circular ssDNA molecule with a size of 1759in case of PCV1 and 1768 for PCV2. They are the smallest mammalian viruses yet known and encode only two major open reading frames, rep and cap. rep and cap perform the two most elementary functions of a virus, copying and the successive packaging of the viral genome. * 高级病理学 9 CTG ORF Genome DNA encodes a protein Homology with PCV-1Location/nt Chain number Molecular/k Da 1 51995 Chain of viral genome 314 35.8 85% 2 17351034 Complementary 233 27.8 66% 3 671357 Complementary 104 11.9 62% 4 565386 Complementary 59 6.5 83% 5 10161177 Chain of viral genome 53 6.2 None 6 16111530 Complementary 27 2.8 None 7 16821741 Chain of viral genome 19 1.9 79% 8 753688 Complementary 21 2.3 67% 9 921732 Complementary 42 4.6 None 10 15241631 Chain of viral genome 35 4.1 None 11 1033989 Complementary 14 1.8 None * 10高级病理学 * 高级病理学 11 3. The viral proteins 1. The largest ORF of the ambisense-organized circoviruses is located on the viral plus-strand (rep gene or ORF1). From ORF1 two proteins are expressed, which are both necessary for viral replication. 2. ORF2 encodes the major structural protein Cap (PCV1: 232 aa; PCV2: 233 aa), which is also the main antigenic determinant of the virus. * 高级病理学 12 0.0kb 1.6kb 1.4kb 1.2kb 1.0kb 0.8kb 0.6kb 0.4kb 0.2kb ORF2 ORF1ORF3 Two major open reading frames (ORFs) have been ecognized for PCV. ORF1,called the rep gene, which encodes a protein of 35.8 kDa involved in virus of replication ,and a protein of 19.2kDa,rep also involved in virus of replication. ORF2, called the cap gene, which encodes the major immunogenic capsid protein of 27.8 kDa * 高级病理学 13 ORF3 is comprised in PCV1 and PCV2 within ORF1, but transcribed counterclockwise. Interestingly, this ORF differs in sequence and size between the two PCV variants: a longer coding region of 621 nt is expressed in PCV1, while it is truncated to 315 nt in PCV2. * 高级病理学 14 Fenaux et al. (2004a) produced chimeric viruses from PCV1 and PCV2 by inserting the cap gene of PCV1 into the PCV2 backbone, PCV2(cap PCV1), and vice versa PCV1(cap PCV2) by replacing the capsid gene of nonpathogenic PCV1 with that of PCV2. After inoculation of pigs with these constructs, seroconversion but no pathogenic effects were observed with either of the chimeric viruses. Since ORF3(PCV2) is comprised in the construct PCV2(cap PCV1), neither ORF3 nor Cap seem to be the only factor contributing to PCV2-induced pathogenesis. * 高级病理学 15 4. Replication of PCV Upon infection, the viral ssDNA genome is converted by host cell factors into a dsDNA replicative form that serves as template for viral DNA replication. The origin of replication is located within the non-coding region between the ORFs of rep and cap and overlaps with the promoter of the rep gene. * 高级病理学 16 5. Virus import PCVs are the smallest viruses that autonomously replicate in mammalian cells. In vivo, viral DNA and antigens are found in monocytic, epithelial and endothelial cells, but no substantial replication was identied in monocytic cells. * 高级病理学 17 * 高级病理学 18 After more than one decade of research addressing the molecular