Rodrigues Alves Lucas Bocchini, Neto Oliveiro Caetano de Freitas, Batista Diego Felipe Alves, Barbosa Fernanda de Oliveira, Rubio Marcela da Silva, de Souza Andrei Itajahy Secundo, Almeida Adriana Maria de, Barrow Paul Andrew, Junior Angelo Berchieri
São Paulo State University (Unesp), School of Agricultural and Veterinary Sciences, Post Graduate Program in Agricultural and Livestock Microbiology, Jaboticabal, SP, Brazil.
Federal University of Paraiba, Department of Veterinary Sciences, Areia, MG, Brazil.
Braz J Microbiol. 2018 Jul-Sep;49(3):601-606. doi: 10.1016/j.bjm.2017.09.006. Epub 2018 Feb 2.
Salmonella Gallinarum is a host-restrict pathogen that causes fowl typhoid, a severe systemic disease that is one of the major concerns to the poultry industry worldwide. When infecting the bird, SG makes use of evasion mechanisms to survive and to replicate within macrophages. In this context, phoPQ genes encode a two-component regulatory system (PhoPQ) that regulates virulence genes responsible for adaptation of Salmonella spp. to antimicrobial factors such as low pH, antimicrobial peptides and deprivation of bivalent cations. The role of the mentioned genes to SG remains to be investigated. In the present study a phoPQ-depleted SG strain (SG ΔphoPQ) was constructed and its virulence assessed in twenty-day-old laying hens susceptible to fowl typhoid. SG ΔphoPQ did cause neither clinical signs nor mortality in birds orally challenged, being non-pathogenic. Furthermore, this strain was not recovered from livers or spleens. On the other hand, chickens challenged subcutaneously with the mutant strain had discreet to moderate pathological changes and also low bacterial counts in liver and spleen tissues. These findings show that SG ΔphoPQ is attenuated to susceptible chickens and suggest that these genes are important during chicken infection by SG.
鸡伤寒沙门氏菌是一种宿主特异性病原体，可引发禽伤寒，这是一种严重的全身性疾病，是全球家禽业主要关注的问题之一。感染禽类时，鸡伤寒沙门氏菌利用逃避机制在巨噬细胞内存活和复制。在这种情况下，phoPQ基因编码一种双组分调节系统（PhoPQ），该系统调节负责沙门氏菌属适应抗菌因子（如低pH值、抗菌肽和二价阳离子剥夺）的毒力基因。上述基因对鸡伤寒沙门氏菌的作用仍有待研究。在本研究中，构建了一株phoPQ缺失的鸡伤寒沙门氏菌菌株（SG ΔphoPQ），并在易患禽伤寒的20日龄产蛋母鸡中评估其毒力。口服攻击禽类时，SG ΔphoPQ既未引起临床症状，也未导致死亡，无致病性。此外，在肝脏或脾脏中未检测到该菌株。另一方面，用突变菌株皮下攻击的鸡出现了轻微至中度的病理变化，肝脏和脾脏组织中的细菌数量也较低。这些发现表明，SG ΔphoPQ对易感鸡的毒力减弱，提示这些基因在鸡伤寒沙门氏菌感染鸡的过程中很重要。
