MODIFICATION OF THE PATHOGENICITY OF PSEUDORABIES VIRUS BY ANIMAL PASSAGE.

Area of Science:

• Virology
• Infectious Diseases
• Animal Models

Background:

• Pseudorabies virus (PRV), also known as "mad itch", is a significant pathogen.
• Understanding PRV strain attenuation is crucial for vaccine development and disease control.

Purpose of the Study:

• To investigate the effects of PRV (Iowa strain) passage through guinea pig brains on its infectivity and pathogenicity.
• To compare the susceptibility of rabbits and guinea pigs to PRV infection.

Main Methods:

• Subcutaneous and intracerebral inoculation of PRV in guinea pigs and rabbits.
• Quantification of PRV in the brains of infected animals.
• Comparative analysis of species susceptibility and viral attenuation.

Main Results:

• PRV passed through guinea pig brains showed reduced infectivity in guinea pigs upon subcutaneous injection, requiring large doses.
• Rabbits were significantly more susceptible (approx. 100x) to subcutaneous PRV infection than guinea pigs.
• Intracerebral PRV inoculation remained pathogenic for both species.
• Guinea pig brains contained approximately one-tenth the viral load per gram compared to rabbit brains after fatal cerebral infection.
• Guinea pig passage demonstrated actual viral attenuation when tested via subcutaneous inoculation in guinea pigs.

Conclusions:

• Passage through guinea pig brains attenuates the PRV Iowa strain, particularly affecting subcutaneous infectivity in guinea pigs.
• Significant differences exist in species-specific susceptibility to PRV, with rabbits being considerably more vulnerable than guinea pigs.
• Viral load and species resistance are key factors influencing PRV pathogenicity.