Restriction of porcine parvovirus replication in nonpermissive cells

Abstract

Swine testicle (ST) cells and Madin-Darby canine kidney (MDCK) cells differ in their ability to support replication of porcine parvovirus (PPV). Viral replication events in ST cells, a permissive cell type, and MDCK cells, a nonpermissive cell type, were compared in an attempt to elucidate putative mechanisms of restrictive virus replication. Radiolabeled PPV bound to the cell surface of both cell types equally well and the binding was shown to be PPV specific, indicating that the restriction was not at the cell surface level. In contrast, profound differences in intracellular events in PPV replication were observed between these two cell types. Synthesis of viral DNA was limited in MDCK cells in that the percentage of cells with replicative-form DNA as determined by strand-specific probe in situ hybridization was approximately 100-fold lower in MDCK cells than in ST cells at the same multiplicity of infection. Northern (RNA) blot analysis, using oligonucleotide probes derived from both structural and nonstructural protein-coding regions of the PPV genome, revealed four PPV mRNA transcripts from infected ST cells. Comparatively, RNA species from the structural protein coding region were actively transcribed in MDCK cells, but synthesis of RNA species from the nonstructural protein coding region was negligible. Immunoprecipitation of viral polypeptides revealed the three characteristic structural polypeptides, VP1, VP2, and VP3, along with the nonstructural polypeptide, NS-1, from ST cells. In contrast, neither viral structural or nonstructural polypeptides nor progeny virions were produced from MDCK cells. The data suggest that mechanisms controlling permissiveness of cells to PPV infection are associated with the level of viral DNA replication, RNA transcription, and viral antigen expression but not absorption to the cell surface.

Multiple amino acids in the capsid structure of canine parvovirus coordinately determine the canine host range and specific antigenic and hemagglutination properties

“…The differences between CPV and FPV capsids may affect some early stage involving attachment, entry, uncoating, or initiation of DNA replication of virus during infection, as has been observed for the tissue tropisms of MVM and PPV (5,30,44,50). Our studies have shown that the restriction of the replication of FPV in canine cells was at an early stage of infection, prior to DNA replication ( Fig.…”

“…4 and 5), and the FPV genome was expressed efficiently in A72 cells after DNA transfection (12). It has been suggested that the receptor is not the determinant of tissue tropism of MVM (50) or PPV (30,44,55). A lack of receptor appears to be unlikely to be the major block in the replication of FPV in canine cells; for example, in Fig.…”

“…Expression of the viral nonstructural protein NS2 was also found to be essential for the lymphotropic phenotype of MVM (8). Studies on the in vitro host range of porcine parvovirus (PPV) showed that the host specificity was determined intracellularly (30,44). A PPV mutant which was adapted to canine A72 cells had changes within both the nonstructural protein and capsid protein gene regions which were involved in host range determination (55).…”

A risk-assessment model to rate the occurrence and relevance of adventitious agents in the production of influenza vaccines

“…When the risk-assessment model was applied to other manufacturing scenarios, the use of Vero cells increased or maintained the overall risk; compared with other scenarios, Vero cells support the growth of a wide range of viruses, including many human pathogens [11][12][13][14][15][16]18,19,[23][24][25]31]. If Vero cells are used instead of eggs for influenza virus isolation or propagation, contamination with avian viruses is avoided.…”

Endocytosis of Non-Enveloped DNA Viruses

“…Shortly after, the CPV2a emerged and this virus was able to infect both species, because it could bind to both receptors. PPV, that can bind and enter many cell types, but that can complete the replication cycle only in few cell types (43).…”