Generation and molecular characteristics of a highly attenuated GPV strain through adaptation in GEF cells

Abstract

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.