A Point Mutation in a Herpesvirus Polymerase Determines Neuropathogenicity

PLoS Pathogens

Ken C Smith¹  Julia H Kydd¹  Nicholas Davis-Poynter¹  Josie Nugent¹  Elizabeth L Buckles²  Gillian A Perkins³  Arianna Loregian⁴  Beatrice Mercorelli⁴  Giorgio Palù⁴  Laura B Goodman⁵  Nikolaus Osterrieder⁵ 

[1] Centre for Preventive Medicine, Animal Health Trust, Newmarket, United Kingdom;Department of Biomedical Sciences, Cornell University, Ithaca, New York, United States of America;Department of Clinical Sciences, Cornell University, Ithaca, New York, United States of America;Department of Histology, Microbiology and Medical Biotechnologies, University of Padua, Padua, Italy;Department of Microbiology and Immunology, Cornell University, Ithaca, New York, United States of America

关键词: Horses;    Ponies;    Viral replication;    Viremia;    Equines;    Central nervous system;    DNA polymerase;    Polymerases;   

DOI  :  10.1371/journal.ppat.0030160

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Infection with equid herpesvirus type 1 (EHV-1) leads to respiratory disease, abortion, and neurologic disorders in horses. Molecular epidemiology studies have demonstrated that a single nucleotide polymorphism resulting in an amino acid variation of the EHV-1 DNA polymerase (N752/D752) is significantly associated with the neuropathogenic potential of naturally occurring strains. To test the hypothesis that this single amino acid exchange by itself influences neuropathogenicity, we generated recombinant viruses with differing polymerase sequences. Here we show that the N752 mutant virus caused no neurologic signs in the natural host, while the D752 virus was able to cause inflammation of the central nervous system and ataxia. Neurologic disease induced by the D752 virus was concomitant with significantly increased levels of viremia (p = 0.01), but the magnitude of virus shedding from the nasal mucosa was similar between the N752 and D752 viruses. Both viruses replicated with similar kinetics in fibroblasts and epithelial cells, but exhibited differences in leukocyte tropism. Last, we observed a significant increase (p < 0.001) in sensitivity of the N752 mutant to aphidicolin, a drug targeting the viral polymerase. Our results demonstrate that a single amino acid variation in a herpesvirus enzyme can influence neuropathogenic potential without having a major effect on virus shedding from infected animals, which is important for horizontal spread in a population. This observation is very interesting from an evolutionary standpoint and is consistent with data indicating that the N752 DNA pol genotype is predominant in the EHV-1 population, suggesting that decreased viral pathogenicity in the natural host might not be at the expense of less efficient inter-individual transmission.

【 授权许可】

CC BY