ABSTRACT
Similar to other parvoviruses, GPV binds to a sialic acidbearing cell surface receptor before entry into the host cell through clathrin-mediated endocytosis. Making use of the phospholipase A2 activity conferred by the amino-terminal peptide of the capsid VP1 protein, GPV penetrates into the cytoplasm and then permeabilizes the host endosomal membrane to facilitate its microtubular transportation toward the nucleus. Inside the nucleus, GPV begins uncoating, and its ssDNA is converted by cellular proteins into dsDNA, which functions as template for synthesis of mRNAs encoding the nonstructural (NS) proteins, NS1 and NS2, when host cell reaches to S phase. Moving out of the nucleus into the cytoplasm, the viral mRNAs are translated into viral proteins by the host ribosomes. After covalent binding to the 5′ genomic end, the NS1 endonuclease transactivates an internal transcriptional promoter that directs synthesis of the structural VP polypeptides. This initiates viral DNA replication via
77.1 Introduction ..................................................................................................................................................................... 693 77.1.1 Classication, Morphology, and Genome Organization ..................................................................................... 693 77.1.2 Replication ........................................................................................................................................................... 693 77.1.3 Clinical Features .................................................................................................................................................. 694 77.1.4 Diagnosis ............................................................................................................................................................. 694
77.2 Methods ........................................................................................................................................................................... 694 77.2.1 Sample Collection and Preparation ..................................................................................................................... 694 77.2.2 Detection Procedures ........................................................................................................................................... 694
77.2.2.1 Virus Isolation ..................................................................................................................................... 694 77.2.2.2 Passive Immunity Test ........................................................................................................................ 694 77.2.2.3 Neutralization Test .............................................................................................................................. 694 77.2.2.4 Cattle Sperm Agglutination Inhibition Test ........................................................................................ 694 77.2.2.5 Agar Gel Precipitin Test ...................................................................................................................... 695 77.2.2.6 Enzyme-Linked Immunosorbent Assay ............................................................................................. 695 77.2.2.7 Western Blotting ................................................................................................................................. 695 77.2.2.8 PCR ..................................................................................................................................................... 695 77.2.2.9 Multiplex PCR .................................................................................................................................... 695 77.2.2.10 Fluorescent Quantitative Real-Time PCR .......................................................................................... 695
77.3 Conclusion ....................................................................................................................................................................... 696 References ................................................................................................................................................................................. 696
a unidirectional strand displacement mechanism, with the hairpin structure at the 3′ end acting as a self-primer to synthesize a plus-sense DNA, leading to the formation of double-stranded DNA. The growing strand can replicate back on itself to produce a tetrameric form that is then cleaved to generate two plus-sense and two minus-sense strands of DNA. Individual ssDNA genomes excised from replication concatemers can be further converted to dsDNA and serve as a template for transcription/replication, or encapsidated and packaged in a 3′–5′ direction to form new virions that are released by cell lysis.
