Date

1-4-2016 12:00 AM

Major

Microbiology; Genetics

Department

Microbiology

College

College of Agriculture and Life Sciences

Project Advisor

Susan Carpenter

Project Advisor's Department

Animal Science

Description

RNA viruses are known for their genetic variability, allowing for rapid adaptation to changing host environments. Genetic and antigenic variation can confer viral escape from the host immune response but can often be associated with a decrease in viral fitness. Porcine reproductive and respiratory syndrome virus (PRRSV) is an RNA virus that causes an economically devastating disease of swine. In order to evaluate fitness costs associated with immune escape, we analyzed a panel of PRRSV variants for trade-offs in viral fitness. To determine if escape was accompanied by changes in replication fitness, the PRRSV variants were characterized for infectivity and growth kinetics in vitro. All four escape variants were significantly less infectious than both the parental FL12 virus and non-escape variants, indicating immune escape is associated with a decrease in infectivity. PRRSV variants differed in replication kinetics, but differences were not associated with an immune escape phenotype. Together, these results indicate that genetic changes in multiple PRRSV envelope proteins conferring immune escape are associated with decreased infectivity, and may alter replication rate.

File Format

application/pdf

Included in

Microbiology Commons

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Apr 1st, 12:00 AM

Now you see me, now you don't: antigenic variation and replication phenotype of Porcine Reproductive and Respiratory Syndrome Virus variants

RNA viruses are known for their genetic variability, allowing for rapid adaptation to changing host environments. Genetic and antigenic variation can confer viral escape from the host immune response but can often be associated with a decrease in viral fitness. Porcine reproductive and respiratory syndrome virus (PRRSV) is an RNA virus that causes an economically devastating disease of swine. In order to evaluate fitness costs associated with immune escape, we analyzed a panel of PRRSV variants for trade-offs in viral fitness. To determine if escape was accompanied by changes in replication fitness, the PRRSV variants were characterized for infectivity and growth kinetics in vitro. All four escape variants were significantly less infectious than both the parental FL12 virus and non-escape variants, indicating immune escape is associated with a decrease in infectivity. PRRSV variants differed in replication kinetics, but differences were not associated with an immune escape phenotype. Together, these results indicate that genetic changes in multiple PRRSV envelope proteins conferring immune escape are associated with decreased infectivity, and may alter replication rate.