Exploratory field study on the effects of porcine circovirus 2 (PCV-2) sow vaccination at different physiological stages mimicking blanket vaccination

Abstract

Background: The objective of the present study was to explore the benefits of Porcine circovirus 2 (PCV-2) blanket vaccination in a sow herd on productive parameters, PCV-2 infection and immune status in sows and their progeny. For this purpose, 288 sows were distributed among four balanced experimental groups. One group remained as negative control group and the other three received 1 mL of PCV-2 Ingelvac Circoflex® intramuscularly at different productive cycle moments: before mating, mid gestation (42-49 days post-insemination) or late gestation (86-93 days post-insemination); phosphate buffered saline (PBS) was used as negative control item. Reproductive parameters from sows during gestation and body weight of their progeny from birth to weaning were recorded. Additionally, blood was collected from sows at each vaccination time and piglets at 3 weeks of age. Moreover, up to 4 placental umbilical cords (PUC) per sow were taken at peri-partum. Sera from sows and piglets were analysed for PCV-2 antibody detection using an enzyme-linked immunosorbent assay (ELISA). Sera from sows and PUC were tested to quantify viraemia using a real time quantitative polymerase chain reaction (qPCR) assay.

Results: Globally, results indicated that vaccinated sows showed heavier piglets at birth and at weaning, less cross-fostered piglets, lower viral load at farrowing as well as in PUC, and higher antibody levels at farrowing, compared to non-vaccinated ones. When all groups were compared among them, sows vaccinated at mid or late gestation had heavier piglets at birth than non-vaccinated sows, and lower proportion of PCV-2 positive PUC. Also, cross-fostering was less frequently practiced in sows vaccinated at pre-mating or mid gestation compared to non-vaccinated ones.

Conclusions: In conclusion, the present study points out that PCV-2 sow vaccination at different time points of their physiological status (mimicking blanket vaccination) offers benefits at production and serological and virological levels.

Keywords: Blanket vaccination; Piglet; Porcine circovirus type 2; Production parameters; Sow.

Fig. 1

PCV-2 IgG OD results (mean ± SD) form sows’ serum samples of the four experimental groups. V PM: vaccinated pre-mating; V MG: vaccinated at mid gestation; V LG: vaccinated at late gestation; NV: non-vaccinated. Different letters indicate statistically significant differences (p ≤ 0.05) among experimental groups for a given sampling point

Fig. 2

PCV-2 IgG S/P values (mean ± SD) from weaned piglets’ serum samples of each experimental group. V PM: vaccinated pre-mating; V MG: vaccinated at mid gestation; V LG: vaccinated at late gestation; NV: non-vaccinated. Different letters indicate significant differences among experimental groups (p ≤ 0.05)

Fig. 3

Phylogenetic tree derived from PCV-2 capsid protein (ORF2) sequences. The tree was constructed by using Maximum-Likelihood method with 1000 bootstrap replicates. Bootstrap values higher than 70 are indicated. Sequences from this study are highlighted in red and labelled with the accession number + PUC (for PUC samples) or S (for sow sample) + sow number

Fig. 4

Experimental study design, including sampling time points and PCV-2 vaccine/PBS application timing. V PM: vaccinated at pre-mating; V MG: vaccinated at mid gestation; V LG: vaccinated at late gestation; NV: non-vaccinated; AI: artificial insemination; PCV-2 vaccine: 1 mL of PCV-2 Ingelvac Circoflex®; PBS: phosphate buffer saline