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The use of veterinary biologicals is an integral component of poultry health programs. All veterinary biologicals are licensed and sold by manufacturing firms under strict regulation by the U.S. Department of Agriculture to ensure purity, potency, efficacy, and safety of the product. The licensing process for a new vaccine is a complex process involving a defined set of studies for each type of vaccine that are performed by the biologics firm, according to approved protocols, with results submitted to the Center for Veterinary Biologics for review. There are 10 classifications of veterinary biologicals and four types of licenses. Manufacturing and testing procedures are also defined within the licensing process. Licensing requirements were initially codified into law. In addition, guidance documents in the form of memoranda and notices have been published to address licensing for additional classes of vaccines and disease agents. This overview of vaccine licensure in the United States is offered to provide a better understanding of the process, the participants, and the factors that influence the time required to produce a commercial product.

Natural antibodies (NAb) are antibodies that can bind to a particular antigen without any apparent antigenic stimulation. In this paper, a careful analysis has been carried out on NAb levels in goat kid serum; possible correlations with the total immunoglobulin (tot-Ig) levels and specific antibody (SpAb) response were considered. Twenty randomly chosen kids were submitted to a first blood sampling (day 0). After 60 and 100 days, new blood samplings were carried out in the same animals. On day 0, after blood collection, all animals were immunized with a commercial vaccine; the immunization was repeated 30 days apart. Some exogenous antigens were tested to verify their immunoreactivity to NAb. Among them, the synthetic hapten 2,4,6-trinitrophenyl (TNP) conjugated with bovine serum albumin, resulted as the antigen with the higher immunoreactivity to NAb. Tot-Ig levels increased over time (p < 0.001). On the contrary, NAb levels, both IgG- and IgM-isotypes, significantly decreased during the experimental period (p < 0.001 and <0.05, respectively). Linear regression analyses showed a high correlation between IgM-NAb and tot-IgM levels (p < 0.001) at all the evaluated sampling times. However, a significant correlation between IgG-NAb and IgM-NAb was found only at the 1 st (p < 0.01) and at the 2 nd sampling (p < 0.05). No significant correlations were found between SpAb response and the other assessed humoral immune parameters. The obtained results are discussed in the light of the possible use of NAb assessment for the evaluation of the immune system activity in goat., (Copyright © 2019 Elsevier B.V. All rights reserved.)