A New Approach to Assessing HSV-1 Recombination during Intercellular Spread.

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Herpes simplex virus type 1 (HSV-1) diversifies through intergenomic recombination.
• Previous studies of HSV-1 recombination are often confounded by attenuating mutations that affect viral replication and spread.

Purpose of the Study:

• To develop and utilize novel fluorescent protein (FP) marked HSV-1 strains to quantify recombination with limited impact on viral fitness.
• To investigate the impact of FP insertion sites on viral replication and progeny production.

Main Methods:

• Generated HSV-1 viruses with cyan or yellow FP expression cassettes inserted at two genomic locations.
• Co-infected neuronal cultures and infected mice with two FP-marked HSV-1 strains.
• Quantified recombinant viral progeny by plaque fluorescence.
• Assessed viral replication and neuroinvasive spread in vitro and in vivo.

Main Results:

• FP-marked HSV-1 genomes showed minimal negative effects on viral replication and progeny production.
• Recombinant progeny formation during co-infection depended on multiplicity of infection but not time.
• Sequential passage resulted in limited changes in parental and recombinant viral populations.
• Neuroinvasive spread in neuronal cultures and mouse models exhibited significant, random shifts in viral population distributions.

Conclusions:

• Fluorescent protein-marked HSV-1 provides a valuable tool for studying viral recombination dynamics.
• HSV-1 recombination rates are influenced by infection parameters but exhibit stochastic behavior during neuroinvasion.