The effect of neonatal vaccination for bovine respiratory disease in the face of a dual challenge with bovine viral diarrhea virus and Mannheimia hemolytica.

Bovine respiratory disease is the greatest threat to calf health. In this study, colostrum-fed dairy X beef calves were vaccinated at ∼30 days of age with an adjuvanted parenteral vaccine containing modified live bovine viral diarrhea virus (BVDV) type 1 and type 2, bovine herpesvirus 1 (BHV-1), bovine parainfluenza type 3 virus (PI3V) and bovine respiratory syncytial virus (BRSV) andM. haemolyticatoxoid (Group 1), or intranasal temperature-sensitive BHV-1, BRSV and PI3V concurrently witha parenteral vaccine containing modified live BVDV type 1 and type 2 andM. haemolyticatoxoid (Group 2) or a placebo (Group 3). The calves were challenged ∼150 days post vaccination intranasally with BVDV 1b and then 7 days later intratracheally withM. haemolytica. The calves wereeuthanized 6 days after theM. haemolyticachallenge. Clinical signs following BVDV infection were similar in all groups. There was increased rectal temperatures in the Groups 2 and 3 on day 3 and in Group 3 on days 8-13. Group 1 animals had a slight leukopenia following BVDV infection while Groups 2 and 3 had greater leukopenia. BVDV type 1 and 2 serum titers increased in Group 1 following vaccination while these titers waned in Groups 2 and 3. There were higher levels of BVDV in the buffy coats and nasal samples in Group 2 and Group 3 versus Group 1 (p < 0.01). Interferon-gamma response was higher (p < 0.01) in Group 1 animals than Groups 2 and 3. Group 1 had the lowest percent pneumonic tissue (1.6%) while Group 2 vaccinates had 3.7% and the control Group 3 was 5.3%. Vaccination in the face of maternal antibody with a parenteral adjuvanted vaccine resulted in better protection than the regimen of an intranasal vaccine anda parenteral adjuvanted BVDV andM haemolyticacombination vaccine in a BVDV-M. haemolyticadual challenge.

Effects of a water-soluble formulation of tylvalosin on disease caused by porcine reproductive and respiratory syndrome virus alone in sows or in combination with Mycoplasma hyopneumoniae in piglets.

BACKGROUND: The effect of a water-soluble formulation of tylvalosin (Aivlosin® 625 mg/g granules) on disease caused by porcine reproductive and respiratory syndrome virus (PRRSV) and Mycoplasma hyopneumoniae (Mhyop) was investigated in two animal studies. In a PRRSV challenge model in pregnant sows (n = 18), six sows received water medicated at target dose of 5 mg tylvalosin/kg body weight/day from 3 days prior to challenge until the end of gestation. Six sows were left untreated, with a third group remaining untreated and unchallenged. Sows were challenged with PRRSV-2 at approximately 85 days of gestation. Cytokines, viremia, viral shedding, sow reproductive parameters and piglet performance to weaning were evaluated. In a dual infection study (n = 16), piglets were challenged with Mhyop on days 0, 1 and 2, and with PRRSV-1 on day 14 and euthanized on day 24. From day 10 to 20, eight piglets received water medicated at target dose of 20 mg tylvalosin/kg body weight/day and eight piglets were left untreated. Cytokines, viremia, bacteriology and lung lesions were evaluated. RESULTS: In the PRRSV challenge study in pregnant sows, tylvalosin significantly reduced the levels of serum IL-8 (P < 0.001), IL-12 (P = 0.032), TNFα (P < 0.001) and GM-CSF (P = 0.001). IL-8 (P = 0.100) tended to be lower in uterus of tylvalosin sows. All piglets from tylvalosin sows surviving to weaning were PRRSV negative in faecal swabs at weaning compared to 33.3% PRRSV positive piglets from untreated sows (P = 0.08). In the dual challenge study in piglet, tylvalosin reduced serum IL1ß, IL-4, IL-6, IL-8, IL-10, IL-12, IL-1α, IL-13, IL-17A, IL-18, GM-CSF, TGFß1, TNFα, CCL3L1, MIG, PEPCAM-1 (P < 0.001) and increased serum IFNα, IL-1ra and MIP-1b (P < 0.001). In the lungs, tylvalosin reduced IL-8, IL-10 and IL-12 compared to untreated pigs (P < 0.001) and tended to reduce TNFα (P = 0.082). Lung lavage samples from all tylvalosin treated piglets were negative for Mhyop (0 cfu/mL) compared to the untreated piglets which had mean Mhyop counts of 2.68 × 104 cfu/mL (P = 0.023). CONCLUSION: Overall, tylvalosin reduced both local and systemic proinflammatory cytokines after challenge with respiratory pathogens in sows and in piglets. Tylvalosin was effective in reducing Mhyop recovery from the lungs and may reduce virus shedding in piglets following transplacental PRRSV infection in sows.