Evolution of avian encephalomyelitis virus during embryo-adaptation
| Autor: | C. Gabriel Sentíes-Cué, H. L. Shivaprasad, Colin Kern, Ying Wang, Rodrigo A. Gallardo, Huaijun Zhou, Rüdiger Hauck |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Gene Expression Regulation
Viral 0301 basic medicine animal structures Picornavirus 040301 veterinary sciences Chick Embryo Microbiology Virus Evolution Molecular 0403 veterinary science 03 medical and health sciences symbols.namesake Animals Tremovirus Poultry Diseases Sanger sequencing Picornaviridae Infections General Veterinary biology Outbreak Viral Vaccines 04 agricultural and veterinary sciences General Medicine Viral Load biology.organism_classification Adaptation Physiological Virology Vaccination 030104 developmental biology Encephalomyelitis Virus Avian Mutation embryonic structures symbols RNA Viral Capsid Proteins Female Flock Chickens Viral load |
| Zdroj: | Veterinary Microbiology. 204:1-7 |
| ISSN: | 0378-1135 |
| DOI: | 10.1016/j.vetmic.2017.04.005 |
| Popis: | Wild-type avian encephalomyelitis virus (AEV) causes neurological signs in young chicks but no disease in pullets after oral or intracutaneous infection. However, if the virus gets embryo-adapted by serial passaging in chicken embryos, it will cause AE after intracutaneous infection in chickens of all ages. Recently, several cases of AE in layer pullets occurring shortly after intracutaneous vaccination were described. The present investigation was initiated to determine if vaccines that had inadvertently been embryo-adapted were responsible for these outbreaks. Virus isolation was done from two vaccines and one field sample. One of the vaccines had been used in one of the flocks before the outbreak. After the first passage, regardless of the inoculum, no embryo was paralyzed, indicating that the vaccines and the field isolate were not embryo-adapted. After seven passages all three strains were fully embryo-adapted causing typical lesions in the embryos. Viral load as determined by RT-qPCR remained constant during the passages. Partial sequences of the VP2 gene of vaccines, the field sample and four other field isolates were nearly identical and highly similar to published sequences from all over the world; only sequences originating from non-vaccinated birds were clearly set apart. Analysis of whole genomes identified two single nucleotide polymorphisms (SNPs) that distinguished wild-type and embryo-adapted strains. Sanger sequencing brains and nerves of the five field isolates and of the first, third and fifth passages of the isolates showed that the mutations indicating embryo-adaptation were first observed in the fifth passage. |
| Databáze: | OpenAIRE |
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