Fernandes Carlos Antônio de Carvalho, Pereira Gustavo Henrique Souza, Pereira Jessica Ruiz, Alves Daniele Cristina, Dias Lucas Souza, Viana João Henrique Moreira, Drumond João
Universidade Prof. Edson Antônio Velano, Alfenas, Minas Gerais, Brazil.
Biotran Assessoria e Consultoria em Medicina Veterinária, Alfenas, Minas Gerais, Brazil.
Front Vet Sci. 2024 Nov 15;11:1440599. doi: 10.3389/fvets.2024.1440599. eCollection 2024.
The aim of this study was to compare the effectiveness of brucellosis control and reproductive performance using one or two doses of RB51 strain vaccine.
This experiment was conducted at two commercial beef farms (A, = 477; and B, = 673), which were selected due to their records of endemic brucellosis and a prevalence of 6 to 8% of seropositive cows. An initial serology screening (Day 0) was carried out in all cows using the Rose Bengal test (RB), and presumptive positive results were re-evaluated using a slow agglutination test with 2-mercaptoethanol (2-ME). Seropositive cows (64, 5.6%) were culled. Non-reactive cows were then randomly assigned into three experimental groups: G1, a single vaccination with RB51; G2, two doses of RB51 given 6 months apart; and G3 (control group), no vaccination. Serological tests were carried out on Days 90, 180, 270, and 360. In each evaluation, seropositive cows were removed. The variables related to occurrence of new infections and abortion, as well as those related to subsequent reproductive performance, were analyzed using the SAS software.
Seropositive cows were still detected in both vaccinated and control groups at 90 days. However, no new infections were detected in G1 at 180 days or in G1 and G2 at 270 and 360 days, whereas new seropositive cows were diagnosed in all exams in G3 (control). Therefore, the cumulative number of new infections was lower in vaccinated than in control cows (0.2% and 0.0%, vs. 3.2% for groups G1, G2, and G3 respectively; = 0.0002). In farm A the number of days open was greater in the control than in vaccinated groups ( < 0.05), and in farm B the pregnancy rate was lower in the control than in the group vaccinated once ( < 0.05). In summary, vaccination with RB51 in beef cows reduces the occurrence of new cases of brucellosis and improves the reproductive performance. There is no indication that a second immunization, six months after the first, enhances protection or reproductive efficiency.
本研究的目的是比较使用一剂或两剂RB51菌株疫苗控制布鲁氏菌病的效果及繁殖性能。
本实验在两个商业肉牛场（A场，477头牛；B场，673头牛）进行，这两个牛场因有地方性布鲁氏菌病记录且血清学阳性奶牛患病率为6%至8%而被选中。在所有奶牛中使用玫瑰红试验（RB）进行初始血清学筛查（第0天），疑似阳性结果用2-巯基乙醇（2-ME）慢凝集试验重新评估。血清学阳性奶牛（64头，5.6%）被淘汰。然后将血清学阴性奶牛随机分为三个实验组：G1组，单剂量接种RB51疫苗；G2组，间隔6个月接种两剂RB51疫苗；G3组（对照组），不接种疫苗。在第90、180、270和360天进行血清学检测。每次评估时，血清学阳性奶牛被剔除。使用SAS软件分析与新感染和流产发生相关的变量，以及与随后繁殖性能相关的变量。
在90天时，接种疫苗组和对照组中仍检测到血清学阳性奶牛。然而，在180天时G1组未检测到新感染，在270天和360天时G1组和G2组均未检测到新感染，而G3组（对照组）在所有检测中均诊断出血清学阳性新奶牛。因此，接种疫苗的奶牛中新感染的累积数量低于对照组奶牛（G1组、G2组和G3组分别为0.2%、0.0%和3.2%；P = 0.0002）。在A场，对照组的空怀天数比接种疫苗组多（P < 0.05），在B场，对照组的妊娠率比单剂量接种疫苗组低（P < 0.05）。总之，肉牛接种RB51疫苗可减少布鲁氏菌病新病例的发生并提高繁殖性能。没有迹象表明在首次接种6个月后进行第二次免疫会增强保护作用或繁殖效率。
