School of Agricultural and Veterinary Sciences, São Paulo State University, Jaboticabal Campus, Jaboticabal-SP 14884-900, Brazil.
Vaccine. 2010 Apr 1;28(16):2853-9. doi: 10.1016/j.vaccine.2010.01.058. Epub 2010 Feb 11.
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.
理想的用于控制商业鸡群中沙门氏菌的活疫苗应能针对各种菌株产生保护作用。本研究的目的是确认缺失参与钴胺素生物合成的 cobS 和 cbiA 基因的鸡沙门氏菌（SG）突变株的减毒情况，并用其作为沙门氏菌活疫苗进行评估。为了评估疫苗的功效，分别进行了两项实验。使用来自商业褐线鸡的鸡进行 SG 野生型菌株的攻毒挑战，使用来自商业白鸡的鸡进行沙门氏菌肠炎型（SE）野生型菌株的攻毒挑战。在这两项实验中，鸡被分为三组（A、B 和 C）。鸡通过以下方案口服接种 SG 突变株：A 组，5 日龄接种 1 剂；B 组，5 日龄接种 1 剂，25 日龄接种 2 剂；C 组，鸡不接种作为对照。45 日龄时，所有组（包括对照组）的鸡均通过 SG 野生型（褐线）或 SE 野生型（白线）进行口服攻毒。最后，进行了另一项实验，以评估 SG 突变株用于预防 1 日龄肉鸡雏鸡 SE 野生型定植盲肠。在褐鸡中评估 SG 野生型的死亡率和系统感染；在白鸡中评估 SE 野生型的粪便脱落和系统感染；在肉鸡雏鸡中评估盲肠定植。接种 1 剂或 2 剂 SG 突变株均能保护褐鸡免受 SG 野生型的侵害。在白鸡实验中，只有接种 2 剂 SG 突变株才能保护鸡免受 SE 野生型的攻毒。然而，SG 突变株不能防止 1 日龄肉鸡雏鸡对攻毒菌株 SE 野生型的盲肠定植。总体而言，结果表明，SG 突变株是一种有前途的沙门氏菌活疫苗候选株，对控制两种对家禽业具有重要意义的血清型的感染具有良好的功效。
