Can the susceptibility of PRRSV infection be different depending on the genetic line of pigs? Can the severity of the symptoms of PRRSV infection be differed by age, gender, or genetic character?
There are indeed differences in the genetic susceptibility of pigs towards PRRSV.
Differences between pigs genetic lines
Already in 1998 it has been demonstrated that certain breeds are less susceptible to PRRS than others; e.g. Meishan pigs had lower PRRS viral titers and less severe lesions than Duroc pigs (Halbur et al. 1998).
Differences within pigs genetic lines
The research investigating genetic susceptibility of pigs towards PRRSV done ever since has shown that also within the same genetic line there is quite some variation in the severity of disease.
A single nucleotide polymorphism (SNP) has been identified on Sus scrofa chromosome 4 (SSC4) which is associated with weight gain and viral load in experimentally infected pigs (Boddicker et al. 2012, 2014a,b; Rowland et al. 2012; Schroyen et al. 2016).
Receptor CD163 and PRRSV disease resistance
The latest research dealing with PRRSV resistance of pigs focused on the receptor CD163 which is necessary to allow PRRSV to enter target cells.
“Genetically modified pigs lacking the complete CD163 molecule were completely resistant to PRRSV-1 and PRRSV-2 (Prather et al. 2013; Wells et al. 2017; Whitworth et al. 2016), while partial deletion of CD163 conferred resistance to PRRSV-1 but not PRRSV-2 (Wells et al. 2017).”
Can the age or gender of the animal influence the severity of PRRSv disease?
Also, age of the pigs, but to my knowledge not necessarily gender, can influence the severity of symptoms.
It was clearly demonstrated that resistance to PRRSV infection increases with age (Klinge et al. 2009); sows are more resistant to virus replication and disease than weaned piglets.
If you want to know more about PRRSv characteristics, please visit our chapter “The PRRS virus” .
University of Veterinary Medicine, Vienna