Effects of injectable trace minerals administered concurrently with a modified live virus vaccine on long-term protection against bovine viral diarrhea virus acute infection in dairy calves

Immune response and onset of protection from Bovine viral diarrhea virus 2 infection induced by modified-live virus vaccination concurrent with injectable trace minerals administration in newly received beef calves

“…The BVDV2 strain 890 was originally acquired from the APHIS Center for Veterinary Biologics in 1989 (Ames, IA), where it was subjected to propagation in Madin-Darby Bovine Kidney (MDBK) cells to keep a viable stock. The stock BVDV2 strain 890 utilized in this trial was biologically cloned using successive passages as previously described (Bittar et al, 2018b). This strain has been previously proven to successfully induce lymphopenia and neutrophilia with mild to moderate clinical disease in non-vaccinated calves (Walz et al, 2001;Bittar et al, 2018b).…”

“…The stock BVDV2 strain 890 utilized in this trial was biologically cloned using successive passages as previously described (Bittar et al, 2018b). This strain has been previously proven to successfully induce lymphopenia and neutrophilia with mild to moderate clinical disease in non-vaccinated calves (Walz et al, 2001;Bittar et al, 2018b).…”

“…The inoculum comprised an infected cell culture supernatant containing 1 × 10 5 50 % tissue culture infectious dose (TCID 50 ) per mL of noncytopathic BVDV2 strain 890. The BVDV isolate was grown in monolayers of MDBK cells using Dulbecco's Modified eagle's medium (DMEM®; Cellgro, Manassas, VA) supplemented with 10 % equine serum (HyClone™ Donor Equine Serum U.S.; Fischer Scientific; Pittsburgh, PA), 1% L-alanyl-L-glutamine (Corning® glutagro 100X Liquid™, 200 mM; Corning Cellgro; Manassas, VA), anti-fungal (Amphotericin B Liquid ®; Corning; Manassas, VA) and antibiotic (Penicillin-Streptomycin Solution 100X®; Corning; Manassas, VA) as previously described (Bittar et al, 2018b). The inocula remained frozen at −80 °C until the day of challenge.…”

“…Then, 5 mL of the BVDV2 inoculum were aliquoted into individual 12 mL sterile syringes, transported to the farm held in ice until use. The challenge was done by intranasal aerosolization of 5 mL of inoculum (2.5 mL in each nostril) with a 10 cm long tip-fenestrated cannula coupled to a 12 mL syringe for each individual animal, as previously described (Bittar et al, 2018b). After challenge all calves comingled in a 10-acre pasture with adequate shade, during the rest of the experimental period.…”

“…Clinical signs were assessed for each variable (hydration status, nasal secretion, head-ears [attitude], feces, eyes, and cough) on a scale from 0 to 3, with 0 representing a lack of clinical signs and 3 representing severe clinical signs. The daily sum health score was the total sum of each individual clinical sign, and was calculated by adding all individual scores of the six clinical variables, as previously described (Bittar et al, 2018b). Three experienced veterinarians, who were not aware of calves' treatment allocation, assessed clinical signs and health scores.…”