Control of Salmonella Enteritidis and Salmonella Gallinarum in birds by using live vaccine candidate containing attenuated Salmonella Gallinarum mutant strain

Abstract

The ideal live vaccine to control Salmonella in commercial chicken flocks should engender protection against various strains. The purpose of the present study was to confirm the attenuation of a Salmonella Gallinarum (SG) mutant strain with deletion on genes cobS and cbiA, that are involved in the biosynthesis of cobalamin. Furthermore, evaluate its use as a live vaccine against Salmonella. For the evaluation of the vaccine efficacy, two experiments were conducted separately. Birds from a commercial brown line of chickens were used to perform challenge with SG wild type strain and birds from a commercial white line of chickens were used to perform challenge with Salmonella Enteritidis (SE) wild type strain. In both experiments, the birds were separated in three groups (A, B and C). Birds were orally vaccinated with the SG mutant as the following programme: group A, one dose at 5 days of age; group B, one dose at 5 days of age and a second dose at 25 days of age; and group C, birds were kept unvaccinated as controls. At 45 days of age, birds from all groups, including the control, were challenged orally by SG wild type (brown line) or SE wild type (white line). Lastly, another experiment was performed to evaluate the use of the SG mutant strain to prevent caecal colonization by SE wild type on 1-day-old broiler chicks. Mortality and systemic infection by SG wild type strain were assessed in brown chickens; faecal shedding and systemic infection by SE wild type were assessed in white chickens and caecal colonization was assessed in broiler chicks. Either vaccination with one or two doses of SG mutant, were capable to protect brown chickens against SG wild type. In the experiment with white chickens, only vaccination with two doses of SG mutant protected the birds against challenge with SE wild type. Although, SG mutant could not prevent caecal colonization in 1-day-old broiler chicks by the challenge strain SE wild type. Overall, the results indicated that SG mutant is a promising Salmonella live vaccine candidate that demonstrated good efficacy to control the infection by two serotypes of major importance to the poultry industry.

Evaluation of the effectiveness and safety of a genetically modified live vaccine in broilers challenged with Salmonella Heidelberg

“…For some time, great efforts have been made towards developing this type of vaccine with gene deletion because even though these are live salmonellas and therefore retain the field challenging behaviour during initial infection, they are also extremely safe as they do not persist in poultry or even in the environment for long periods of time (Hoiseth & Stocker, 1981;Barrow et al, 1990;Hormaeche et al, 1991;Cooper et al, 1994;Tan et al, 1997;Van Immerseel et al, 2002). Thus, the great advantage of genetically modified live vaccines is the low risk of reversion to virulence in comparison to vaccines made from attenuated rough strains, for example (Frey, 2007;Matsuda et al, 2010;Penha Filho et al, 2010;Matsuda et al, 2011a, b;Shehata et al, 2013;Van Immerseel et al, 2013).…”

A Trial to Prevent Salmonella Enteritidis Infection in Broiler Chickens Using Autogenous Bacterin Compared with Probiotic Preparation

“…There are numbers of live and killed S. Enteritidis vaccines used commercially worldwide with some success. The efficacy of live attenuated S. Enteritidis vaccines was studied (Arnon et al, 1983;Barrow et al, 1990;Barrow 2000 andAtterbury et al, 2010;Penha et al, 2010;Methner et al, 2011) and the vaccine proved its efficacy but it could be hazardous because of residual virulence caused by insufficient attenuation, reversion to virulence and uncertain safety (Barbezange et al, 2000), so its use is prohibited in several countries. However, inactivated S. Enteritidis vaccine had been developed and can confer partial protection against intestinal colonization, fecal shedding, systemic spread and egg contamination (Timms et al, 1990;Gast et al, 1993;Nakamura et al, 1994;Timms et al, 1994;Davison et al, 1999;Miyamoto et al, 1999;Liu et al, 2001;Khan et al, 2003;Okamura et al, 2003;Nakamura et al, 2004;Haider et al, 2007;Cima 2010).…”

Salmonella enterica Serovar Enteritidis Ghosts Carrying the Escherichia coli Heat-Labile Enterotoxin B Subunit Are Capable of Inducing Enhanced Protective Immune Responses

“…Infected poultry meat and eggs are the primary repositories for the strains of S. Enteritidis associated with human illness (3). S. Enteritidis-infected chickens do not show severe symptoms of infection; rather, they maintain a carrier state, which results in bird-tobird spread of S. Enteritidis through vertical transmission and fecal shedding (4). The establishment of protective immunity by bird vaccination has been proposed as an ideal strategy for preventing S. Enteritidis infection on poultry farms (5).…”