TABLE 1.
Summary of clinical symptoms in pigs
| Virus | Presence of:
|
Incidence of death | ||
|---|---|---|---|---|
| Fever | Respiratory signs | Neurological signs | ||
| Primary infectiona | ||||
| PrV-Ka | +++ | +++ | ++ | 1/4 |
| PrV-gD− Pass SPH | − | − | − | 0/6 |
| PrV-gD− Pass | − | − | − | 0/6 |
| Challenge infectionb | ||||
| PrV-Ka | − | − | − | 0/3 |
| PrV-gD− Pass SPH | − | − | − | 0/6 |
| PrV-gD− Pass | +++ | +++ | ++ | 2/6 |
| Control | +++ | +++ | +++ | 3/3 |
a
Three groups of 6-week-old piglets were infected intranasally with 106 PFU of PrV-Ka (four animals), PrV-gD− Pass (six animals), or PrV-gD− Pass SPH (six animals). Clinical signs, such as fever, respiratory, or neurological symptoms, were recorded daily and graded as follows: +++, severe; ++, moderate; +, weak; −, none. The last column records deaths versus total number of animals per group.
b
Surviving animals from the primary infection as well as three age-matched naive control animals were challenge infected intranasally with 5 × 107 pfu of highly virulent PrV-NIA-3, and clinical signs were again recorded daily as described for primary infections.