چکیده (انگلیسی):

Objective: To evaluate/predict the offspring serum profile of antibodies against Porcine
reproductive and respiratory syndrome virus (PRRSV) in an affected intensive herd,
whereas sows are vaccinated, and determine the better sample time using pigs as
sentinels.
Methods: Serum samples were collected from a total of 66 offspring pigs from a PRRSV
endemic herd, whereas only sows were vaccinated. Six animals per grouped age were
randomly selected with 0 (at perinatal time), 1, 2, 3, 6, 9, 12, 15, 18, 21 and 24 weeks of
age. Individual and three pooled samples were tested by ELISA and PCR, respectively.
Results: The proportion of seropositive animals was 75.0% (18/24), 33.3% (6/18) and
95.8% (23/24) at farrowing (0–3 weeks), nursery (6–12 weeks) and growing/finishing
(15–24 weeks) phases, respectively. It was 46 times more likely (P < 0.01) to observe
seropositive pigs on the growing/finishing than on nursery phase. European PRSSV strain
was detected on serum of 6, 9 and 15-weeks-old pigs. Polynomial fit degree 4 regression
between sample-to-positive (S/P) ratios and age of pigs (r = 0.78; R2 = 0.60; P < 0.001)
estimated a quickly decrease of maternal antibodies, above 0.4 S/P value (cut off), until
the 6th week following by a progressive increment of humoral immunity until 21st week
of age, when it declines.
Conclusions: The results indicate that the piglets can present viremia early at nursery,
and the 18th – 21st weeks are the best time to sample offspring pigs, as sentinel, from
PRRSV contaminated intensive herds.