Purpose

This study aimed to investigate the diversity of Balantioides coli (B. coli) based on the 18S rDNA of isolates collected from weaned pigs with diarrhea and then select a B. coli isolate to determine its pathogenicity in weaned pigs through experimental infection.

Methods

The genetic analysis of field-isolated B. coli strains was based on sequencing of the partial 18S rDNA genetic fragment and the pathogenicity of an isolate of B. coli (DN2018-2-DTD) was identified through an experimental infection.

Results

The fourteen B. coli isolates shared 98.47–100% nucleotide similarity and were divided into two clades in a phylogenetic tree. In an infection experiment, a slight increase in the body temperature was identified in two infected groups as compared to that in the control group (P < 0.05) from days post-infection (dpi) 12–18 and from dpi 20–27. In the group infected with 3000 CPG/TPG, 2/9 pigs started to develop diarrhea on day two. In the group infected with 500 CPG/TPG, 8/9 pigs had diarrhea on dpi 3. Trophozoites/cysts of B. coli were firstly detected in feces on dpi 3 in a group of pigs infected with a dose of 3000 CPG/TPG, and CPG/TPG reached its peak at dpi 5 in both groups of infected pigs (35,450 and 13,250 CPG/TPG). There was a significant difference in the bodyweight of the control group (noninfected) as compared to that of the groups of infected pigs on dpi 7 (P < 0.05), 14 (P < 0.001) and 28 (P < 0.01). Lesions were solely recorded in infected pigs, including white ulcerative nodules with necrosis scattered in the mucosa of the colon and cecum on dpi 7, 14, and 28.

Conclusion

This is the first study to investigate the pathogenicity of B. coli in Vietnamese pigs to demonstrate that B. coli could induce necrotic ulcerative enteritis and diarrhea in weaned pigs.

中文翻译：

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越南断奶猪中分离株 Balantioides coli 的系统发育和致病性

目的

本研究旨在利用从腹泻断奶猪身上采集的分离株的18S rDNA ，调查Balantioides coli  ( B. coli )的多样性，然后通过实验感染选择一株B. coli  ，确定其对断奶猪的致病性。 

方法

现场分离的大肠杆菌菌株的遗传分析基于对部分18S rDNA基因片段的测序，并通过实验感染确定了大肠杆菌分离株 (DN2018-2-DTD) 的致病性。

结果

十四个大肠杆​​菌分离株具有98.47-100   % 的核苷酸相似性，并在系统发育树中分为两个进化枝。 在感染实验中，与对照组相比，从感染后 (dpi) 12-18 天和 dpi 20-27 天开始，两个感染组的体温略有升高 ( P < 0.05)。在感染 3000 CPG/TPG 的组中，2/9 的猪在第二天开始出现腹泻。在感染 500 CPG/TPG 的组中，8/9 头猪在 dpi 3 时出现腹泻。滋养体/大肠杆菌包囊  在感染剂量为 3000 CPG/TPG 的猪组中，首次在 dpi 3 的粪便中检测到 CPG/TPG 在两组感染猪（35,450 和 13,250 CPG/TPG）中在 dpi 5 时达到峰值。在 dpi 7（ P  < 0.05）、14（P  < 0.001）和 28（P  < 0.01）时，对照组（未感染）的体重与感染猪组相比有显着差异。仅在受感染的猪中记录了病变，包括在 dpi 7、14 和 28 时散布在结肠和盲肠黏膜中的白色溃疡性结节和坏死。

结论

这是第一项研究B.  coli 对越南猪的致病性，以证明B.  coli 可在断奶猪中诱发坏死性溃疡性肠炎和腹泻。