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Salmonella Gallinarum mgtC mutant shows a delayed fowl typhoid progression in chicken.

Authors :
Rodrigues Alves LB
Freitas Neto OC
Saraiva MMS
do Monte DFM
de Lima BN
Cabrera JM
Barbosa FO
Benevides VP
de Lima TS
Campos IC
Rubio MDS
Nascimento CF
Arantes LCRV
Alves VV
de Almeida AM
Olsen JE
Berchieri Junior A
Source :
Gene [Gene] 2024 Jan 20; Vol. 892, pp. 147827. Date of Electronic Publication: 2023 Sep 23.
Publication Year :
2024

Abstract

Salmonella Gallinarum (SG) provokes fowl typhoid, an infectious disease of acute clinical course that affects gallinaceous of any age and leads to high mortality rates. During the typhoid-like systemic infection of S. Typhimurium (STM) in mice, the bacterium expresses the mgtC gene, which is encoded in the Salmonella Pathogenecity Island - 3 (SPI-3). In this serovar, the function is linked to bacterial replication within macrophages, and its absence attenuates the pathogen. We hypothesized that deleting mgtC from SG genome would alter the microorganism pathogenicity in susceptible commercial poultry in a similar manner. Thus, the present study sought to elucidate the importance of mgtC on SG pathogenicity. For this, a mgtC-mutant lacking S. Gallinarum mutant was constructed (SG ΔmgtC). Its ability to replicate in medium that mimicries the mgtC-related intracellular environment of macrophages as well as in primary macrophages from chicken was evaluated. Moreover, the infection of susceptible chickens was performed to elucidate its pathogenicity and the elicited immune responses by measuring key interleukins by qRT-PCR and the population of macrophages and lymphocytes T CD4 <superscript>+</superscript>  and CD8 <superscript>+</superscript>  by means of immunohistochemistry. It was observed that mgtC was required for S. Gallinarum replication in acidified low-Mg <superscript>2+</superscript>  media and survival within macrophages. However, unlike its requirement for initial phase of STM infection in mice, lower bacterial counts were only observed at the late stage of macrophage infection without affecting the citotoxicity. Experiments showed that knocking-out the mgtC gene neither altered bacterial uptake by macrophages nor affects bacterial counts in liver and spleen and total chicken mortality. However, plotting a survival curve and analyzing the clinical-pathologic conditions, it was observed a slower progression of the disease in chickens infected by SG ΔmgtC compared to those challenged by the wild-type strain. Furthermore, the mRNA expression of IFN-γ and LITAF were similar between the infected chickens, but higher than in the uninfected group. The same was observed in macrophages and lymphocytes T CD4 <superscript>+</superscript>  populations. On the other hand, the presence of lymphocytes T CD8 <superscript>+</superscript>  was increased in the initial phase of the disease provoked by the wild-type strain over the mutant strain. We concluded that the role of mgtC in Fowl Typhoid in susceptible chickens differs from the role in typhoid-like infections in mammals. Thus, the deletion of mgtC gene from S. Gallinarum genome does not affect the overall pathogenicity, but slightly alters the pathogenesis.<br />Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.<br /> (Copyright © 2023 Elsevier B.V. All rights reserved.)

Details

Language :
English
ISSN :
1879-0038
Volume :
892
Database :
MEDLINE
Journal :
Gene
Publication Type :
Academic Journal
Accession number :
37748627
Full Text :
https://doi.org/10.1016/j.gene.2023.147827