Transmission of two pseudorabies virus strains that differ in virulence and virus excretion in groups of vaccinated pigs.
OBJECTIVE
To determine whether 2 pseudorabies virus (PRV) strains that differ in virulence differ in transmission among vaccine strain 783-inoculated pigs.


METHODS
Three experiments were conducted, each with 2 groups of 10 pigs inoculated with the glycoprotein E-negative vaccine 783. In the first 2 experiments, half of one group was inoculated with the mildly virulent strain Sterksel, and half of the other group was inoculated with the virulent strain NIA-3. The remaining pigs were contact-exposed to the inoculated pigs. In the third experiment, 2 pigs in each group were inoculated with strain NIA-3, and the other 8 pigs in each group were contact-exposed to these 2 pigs.


METHODS
Specific-pathogen-free pigs that were sero-negative for antibodies to PRV.


METHODS
Estimation of the transmission of virus in each group was based on a stochastic model, in which the observable variable was the number of contact infections. The sole parameter of the model was the reproduction ratio theta. A glycoprotein E ELISA was used to determine whether infection occurred. Virus excretion in the oropharyngeal fluid was determined by plaque assay to measure infectivity.


RESULTS
Vaccinated pigs had a significant difference in virus excretion between the mildly virulent and virulent strains. Sterksel strain-inoculated pigs shed significantly more virus than did NIA-3 strain-inoculated pigs. Despite this difference in virus excretion, the 2 strains did not differ in transmission.


CONCLUSIONS
Both PRV strains would be eliminated from a population of vaccine strain 783-inoculated pigs.
Bouma
A
A
DLO-Institute for Animal Science and Health, Lelystad, Netherlands.
De Jong
M C
MC
Kimman
T G
TG
D000704:Analysis of Variance; D000818:Animals; D002460:Cell Line; D011558:Herpesvirus 1, Suid / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D007668:Kidney; D008433:Mathematics; D011557:Pseudorabies / Q000276:immunology / Q000517:prevention & control / Q000635:transmission*; D013269:Stochastic Processes; D013552:Swine; D014611:Vaccination; D014765:Viral Vaccines; D014774:Virulence
D014765:Viral Vaccines