Background: Goose parvovirus (GPV) has spread globally and causes huge ecomonic loss to poultry industry. Although the attenuated GPV vaccines play vital roles in preventing the disease caused by GPV, the molecular basis for the attenuation of GPV is barely known. Results: A highly attenuated GPV strain GPV-CZM-142 was generated through blindly passaging of the highly pathogenic strain GPV-CZM in goose embryo fibroblasts (GEF) for 142 generations. The virulence of the GEF-adapted GPV strain was 10000 times less than that of the wild type GPV-CZM based on the ELD50. Genome sequencing revealed that a novel insertion in ITR and host adapted mutations in NS and VP1 were found in GPV-CZM-142 in comparison with the wild type strain.Conclusions: The generation of the highly attenuated GPV strain GPV-CZM-142 and the identified virulence-related insertion/mutation profile in the genome not only provided GPV attenuated vaccine candidate, but also gives novel insights into the molecular determinants for GPV attenuation.

Background: Goose parvoviruses (GPVs) spread globally and cause a huge economic loss to the poultry industry. Although the attenuated GPV vaccines play a key role in preventing the disease caused by GPV, the molecular basis for the attenuation of GPV is barely known. Results: A highly attenuated GPV strain, GPV-CZM-142, was generated through blindly passaging of the highly pathogenic strain, GPV-CZM, in goose embryonic fibroblasts (GEF) for 142 generations. The GEF-adapted GPV strain's virulence was 10,000 times weaker than its wild type counterpart, GPV-CZM, based on the ELD50 (50% Embryo Lethal Dose). By comparing with the wild type strain, genome sequencing analysis identified adapted mutations either in ITR or in NS and VP1 of GPV-CZM-142.Conclusions: The highly attenuated GPV strain, GPV-CZM-142, provides a GPV vaccine candidate, and the identified virulence-related mutations give a novel insight into the molecular determinants of GPV virulence.

Background: Goose parvoviruses (GPVs) spread globally and cause a huge economic loss to poultry industry. Although the attenuated GPV vaccines play a key role in preventing the disease caused by GPV, the molecular basis for the attenuation of GPV is barely known. Results: A highly attenuated GPV strain, GPV-CZM-142, was generated through blindly passaging of the highly pathogenic strain, GPV-CZM, in goose embryonic fibroblasts (GEF) for 142 generations. The virulence of the GEF-adapted GPV strain was 10000 times weaker than that of its wild type counterpart, GPV-CZM, based on the ELD50. By comparing with the wild type strain, genome sequencing analysis identified a novel insertion in ITR and several other mutations in both NS and VP1 of GPV-CZM-142.Conclusions: The highly attenuated GPV strain, GPV-CZM-142, provides a GPV vaccine candidate, and the identified virulence-related insertion/mutations give a novel insight into the molecular determinants of GPV virulence.