Age-Dependent Differences in Pseudorabies Virus Neuropathogenesis and Associated Cytokine Expression

Area of Science:

• Veterinary Virology
• Immunology
• Neuropathogenesis

Background:

• Alphaherpesvirus infections cause more severe disease in newborns than older individuals.
• Mechanisms underlying age-dependent neuropathogenesis in pseudorabies virus (PRV) infections remain unclear.
• Pigs serve as a natural host model for studying PRV age-related virulence.

Purpose of the Study:

• To investigate the age-dependent mechanisms of pseudorabies virus (PRV) neuropathogenesis in pigs.
• To elucidate the role of viral replication and immune response in PRV-induced neurological disease.
• To compare PRV infection outcomes in 2-week-old versus 15-week-old pigs.

Main Methods:

• Inoculation of 2- and 15-week-old pigs with PRV strain NIA3.
• Quantitative PCR analysis of viral DNA in various organs.
• Analysis of viral and cytokine mRNA expression in key neuropathogenesis sites.

Main Results:

• PRV infection severity and mortality were higher in younger pigs.
• Viral replication was less pronounced in the trigeminal ganglia (TG) and brain stem of older pigs.
• Extensive viral replication and cytokine mRNA expression in the olfactory bulbs correlated with neurological disease in both age groups.

Conclusions:

• Age-dependent differences in PRV clinical signs are linked to enhanced viral replication and immunopathology in immature neurons of young pigs.
• Neurological disease in pigs is associated with extensive viral replication and immune response in the olfactory bulb.
• PRV neuropathogenesis involves complex interactions between viral replication, neuronal development, and immune responses, varying with host age.