Interface between maternal antibodies and natural challenge for Bovine Viral Diarrhea Virus (BVDV) in Holstein heifers
Baccili, Camila CostaSobreira, Natália MeirellesSilva, Bruno ToledoPituco, Edviges MaristelaGomes, Viviani
Background: Newborn calves are agammaglobulinemic, immunosuppressed and immunologically immature at birth. The passive immune transfer is fundamental to protect calves against pathogens. The decay of maternal antibodies precedes the immune maturation at puberty enhancing the susceptibility of calves to infections caused by BVDV. Then, the objective of this research was to evaluate the interface between passive and active immunity for Bovine Viral Diarrhea Virus (BVDV) in Holstein dairy heifers in the first 13 months of age to detect susceptibility periods and establish prophylactic measures on prevention of Bovine Viral Diarrhea.Materials, Methods & Results: Sera were analyzed from 585 heifers by serum neutralization (SN) and enzyme linked immunosorbent assay (ELISA) for the p80 protein of BVDV. Heifers were categorized according to their age by the month of life. Heifers were seropositive (100%) from 1st to 13th. Median of neutralizing antibodies (Ab) titers obtained from 1st up to 13th month were 316.2; 125.9; 63.1; 50.1; 50.1; 39.8; 63.1; 63.1; 39.8; 79.4, 100.0; 74.4; and 79.4, respectively. The neutralizing Ab titers obtained in 1st month were different of the values observed from 2nd until 13th (P 0.001), furthermore the Ab titers from 2nd month was statistical different of 4th (P = 0.01) and 6th (P = 0.05). The frequencies (%) of positive heifers for p80 from 1s [...](AU)
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