Effect of Spray Escherichia coli Vaccine on the Immunity of Poultry

Abstract

Avian pathogenic Escherichia coli is a current problem in the poultry industry, causing mortality and economic losses. This paper evaluates the dynamics in immune response after the use of spray vaccination against E. coli and, thereby, seeks to understand how the vaccine can provide protection. During the early stages of response to vaccination the presence of antigen-presenting cells is predominant, but these diminish within the first 7 days after vaccination. The immune correlate of protection of vaccination using the E. coli vaccine Poulvac E. coli (aroA-deficient mutant strain) probably does not depend on the production of circulating antibodies (as assessed through the presence of B lymphocytes) and is linked to the presence of CD4+TCRVbeta1+. These cells act on mucosa tissue stimulating the production of immunoglobulin A. Vaccination stimulated a high state of immunocompetence, as assessed by measurement of several cellular subsets. This state of "immune alertness," however, may be associated with reduced weight gain. The high presence of naive and memory CD8 cells in the vaccinated group at 14 and 21 days postvaccination may indicate greater ability in the future to prevent tissue invasion by E. coli, based on the possibility that these cells will proliferate rapidly to a new stimulus. The simultaneous use of vaccine with the antibiotic ceftiofur sodium interferes with the immune response obtained through vaccination. In combination, the data obtained in this study indicate that the immune response produced by a spray vaccine against E. coli is mainly a cellular response, especially relevant to the sites in contact with the pathogen. It is suggested that there is a strong cell migration to the mucous membranes, where macrophages act first and then lymphocytes take part to protect the host. It is believed that recruited lymphocytes will act in the production of secreted IgA, which probably plays a greater role in the defense when compared with circulating immunoglobulins. The assessment of cellular dynamics by flow cytometry made it possible to elucidate the operation mechanism of the live E. coli vaccine.

An Assessment of the Level of Protection Against Colibacillosis Conferred by Several Autogenous and/or Commercial Vaccination Programs in Conventional Pullets upon Experimental Challenge

“…The combination of live and autogenous vaccines seems to have triggered a wider immunization spectrum, as observed in turkeys by Sadeyen et al [ 43 ]. In commercial broilers, the immune response produced by a spray live vaccine against E. coli is mainly a cellular response, especially relevant to the sites in contact with the pathogen, as indicated by data obtained by Filho et al [ 44 ].…”

Immune responses associated with homologous protection conferred by commercial vaccines for control of avian pathogenic Escherichia coli in turkeys

“…Similarly, whilst live-attenuated mutants of various kinds can confer resistance against APEC in target host species [ 21 , 22 , 30 , 42 - 44 ], the innate and cell-mediated responses they elicit are ill-defined. Studies by Fernandez Filho et al [ 43 ] with Poulvac® E. coli only examined peripheral cellular responses to vaccination, with a fine spray, of day-old chicks. No booster was given to those birds at 7 days of age via drinking water as is recommended [ 22 ].…”

“…A recent field trial of Poulvac® E. coli [ 42 ] also supports that giving a booster in drinking water is not necessary. Interestingly, a higher level of peripheral B lymphocytes was detected in the control than the vaccinated group and the authors speculated that Poulvac® E. coli may suppress humoral responses and that they may therefore be dispensable in protection [ 43 ]. In support of this, Salehi et al [ 44 ] also reported a lack of significant induction of antibody response in chickens after aerosol administration of an independent aroA mutant of E. coli .…”

Live and Inactivated <i>Salmonella</i> Enteritidis Vaccines: Immune Mechanisms in Broiler Breeders

“…The same animals were studied throughout the experiment, allowing a continuous analysis of the fluctuation of immune parameters. Flow cytometry was performed as previously described [14]. Briefly, mononuclear cells from peripheral blood were separated by Histopaque-1077 (Sigma).…”