Variability of pseudorabies virus glycoprotein I expression

Area of Science:

• Virology
• Immunology
• Molecular Biology

Background:

• Pseudorabies virus (PRV) glycoprotein I (gI) is a major envelope constituent.
• gI is not essential for PRV replication, with vaccine strains lacking it.
• Alterations in gI expression can occur spontaneously.

Purpose of the Study:

• To investigate spontaneous alterations in PRV gI expression.
• To determine the impact of altered gI expression on antibody neutralization.
• To evaluate the suitability of gI as a subunit vaccine.

Main Methods:

• Characterization of a PRV field isolate expressing a modified gI precursor (pgI).
• Analysis of gI expression and antibody neutralization in PRV strains (Phylaxia, NIA-5, Ka) after in vitro passage.
• Assessment of genomic and transcriptional stability.

Main Results:

• A PRV field isolate expressed a 64-kDa pgI processed into 60-kDa gI, resistant to anti-gI monoclonal antibodies.
• In vitro passage of PRV NIA-5 led to pgI appearance and increased resistance to neutralization.
• Variable gI/pgI expression in PRV Ka isolates correlated with differential antibody neutralization susceptibility.
• gI expression was stable in PRV Phylaxia isolates.

Conclusions:

• PRV strains resistant to anti-gI antibodies arise spontaneously in vivo and in vitro.
• The observed viral evolution challenges the use of gI as a target for subunit vaccines.
• Further research is needed to understand the mechanisms of gI alteration and its implications for PRV control.