Targeted Modification of the Foot-And-Mouth Disease Virus Genome for Quick Cell Culture Adaptation
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Published on: November 1, 2011
Veronika Dill1, Aline Zimmer2, Martin Beer1
1Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Federal Research Institute for Animal Health, 17493 Greifswald-Insel Riems, Germany.
Abstract:
Foot-and-mouth disease virus (FMDV) causes the highly contagious foot-and-mouth disease, which is characterized by the appearance of vesicles in and around the mouth and feet of cloven-hoofed animals. BHK-21 cells are the cell line of choice for the propagation of FMDV for vaccine production worldwide but vary in their susceptibility for different FMDV strains. Previous studies showed that the FMDV resistance of a certain BHK cell line can be overcome by using a closely related but permissive cell line for the pre-adaptation of the virus, but the adapted strains were found to harbor several capsid mutations. In this study, these adaptive mutations were introduced into the original Asia-1 Shamir isolate individually or in combination to create a panel of 17 Asia-1 mutants by reverse genetics and examine the effects of the mutations on receptor usage, viral growth, immunogenicity and stability. A single amino acid exchange from glutamic acid to lysine at position 202 in VP1 turned out to be of major importance for productive infection of the suspension cell line BHK-2P. In consequence, two traditionally passage-derived strains and two recombinant viruses with a minimum set of mutations were tested in vivo. While the passaged-derived viruses showed a reduced particle stability, the genetically modified viruses were more stable but did not confer a protective immune response against the original virus isolate.
Insights
Foot-and-mouth disease virus (FMDV) adaptation in BHK-21 cells requires specific mutations, like VP1 E202K, for improved growth. While genetically modified FMDV strains show enhanced stability, they may not induce protective immunity against the original virus.
Area of Science:
- Virology
- Molecular Biology
- Immunology
Background:
- Foot-and-mouth disease virus (FMDV) causes a highly contagious disease in cloven-hoofed animals.
- BHK-21 cells are crucial for FMDV vaccine production but exhibit variable susceptibility to different FMDV strains.
- Previous adaptation strategies involved using related cell lines, leading to FMDV capsid mutations.
Purpose of the Study:
- To investigate the impact of adaptive mutations on FMDV properties using reverse genetics.
- To analyze the effects of specific mutations on FMDV receptor usage, growth, immunogenicity, and stability.
- To evaluate the in vivo performance of FMDV mutants compared to passage-derived strains.
Main Methods:
- Introduction of adaptive mutations into the FMDV Asia-1 Shamir isolate via reverse genetics, creating 17 mutants.
- Analysis of mutations' effects on receptor usage, viral growth, immunogenicity, and particle stability.
- In vivo testing of passage-derived strains and recombinant viruses with minimal mutations.
Main Results:
- A single amino acid substitution (E202K in VP1) was critical for productive infection in the BHK-2P cell line.
- Genetically modified FMDV strains exhibited greater particle stability compared to traditionally passaged strains.
- Despite enhanced stability, the modified FMDV strains did not elicit a protective immune response against the original isolate.
Conclusions:
- Specific mutations, particularly E202K in VP1, are essential for adapting FMDV to grow in BHK-2P cells.
- Reverse genetics allows for the creation of stable FMDV variants, but stability does not guarantee protective immunogenicity.
- Further research is needed to develop FMDV vaccine candidates that balance viral stability and effective immune protection.
