Effects of deoxynivalenol (DON) on PRRSV immunization and challenge Infection: An experimental study

Deoxynivalenol (DON) is a mycotoxin produced by Fusarium spp. and is a common contaminant of grains worldwide. DON has been shown to increase susceptibility to viral infections. The objective of this study was to investigate the impact of DON on porcine reproductive and respiratory syndrome virus (PRRSV) immunization and subsequent challenge infection in vivo.

In total 38 piglets were divided into four groups. Group I (10 animals) was immunized using a modified live Genotype 2 based vaccine and subsequently challenged intranasally with 2ml of a PRRSV Genotype 1 field strain containing 1 x 10⁵ TCID₅₀/ml. Group 2 (10 animals) was similarly immunized and challenged in the presence of a diet containing 1 mg/kg DON. Group 3 (10 animals) was also similarly immunized and challenged in the presence of a diet containing 2 mg/kg DON. Group 4 (8 animals) served as infection control and was infected with the Genotype 1 field strain without prior immunization and without DON containing diet. Animals were monitored daily using a clinical score which included apathy, dyspnea, sneezing, body temperature, cyanosis, conjunctivitis, nasal and ocular discharge. Specific antibody responses were measured weekly. Blood and organ samples were used for quantification of genotype 1 and 2 viruses.

Two weeks post immunization PRRSV specific antibody responses were observed in all animals of group 1 and 2. The development of PRRSVspecific antibodies was delayed in individual animals of group 3. Animals of group 4 developed the highest clinical score demonstrating the virulence of the used challenge virus. Animals of group 1 developed the lowest clinical score. In contrast, animals of group 2 and especially group 3 showed increased clinical scores almost reaching the scores of group 4. Results of the virus quantification revealed that virus loads also differed among the treatment groups.

The current study exemplifies that DON has marked effects on the clinical outcome of PRRSV challenge infection in prior immunized piglets.

Disclosure of Interest: None Declared.