Objective: To investigate the association between intestinal colonization of segmented filamentous bacteria (SFB) and the risk of rotavirus infection, and the possible mechanisms by which SFB resist rotavirus infection. Methods: This case-control study enrolled 50 children aged 0 to 5 years who present to the outpatient Department of Children\'s Hospital, Zhejiang University School of Medicine with diarrhea and positive stool tests for rotavirus. The children were divided into rotavirus
enteritis group and control group consisting of 55 children with non-gastrointestinal and non-infectious surgical diseases.The age and sex composition of the two groups was matched. The DNA of the fecal flora was extracted and SFB was detected by real-time fluorescence quantitative PCR analysis. The children in the rotavirus
enteritis group and the control group were subgrouped by age and sex to analyze the differences in SFB positivity rates between different groups, and further compare and analyze the differences in SFB positivity rates between these two groups of children in the ≤2 years old subgroup and the >2-5 years old subgroup. Neutralization test was performed with p3340 protein and rotavirus to determine the relationship between rotavirus infection rate and p3340 concentration in Vero cells. χ2 test or Fisher\'s exact probability method was used for comparison between the two groups. Results: There were 50 children in the rotavirus
enteritis group with an age of (1.7±0.9) years, and 55 children in the control group with an age of (1.8±1.1) years. The positive rate of SFB in children with rotavirus enteritis showed a declining trend across ages groups, with the highest rate of 10/14 in the ≤1 year old group, followed by 67% (14/21) in the >1-2 years old group, 9/15 in the >2-5 years old group, and there was no statistically significant difference (P=0.867). The positive rate of SFB in the control group was 12/15 in the ≤1 year old group, 95% (19/20) in the >1-2 years old group, 50% (10/20) in the >2-5 years old group, with statistical significance (P=0.004). The positive rate of SFB in children with rotavirus
enteritis was 74% (20/27) in males and 56% (13/23) in females (χ2=1.71, P=0.192). In the control group, it was 79% (22/28) in males and 70% (19/27) in females (χ2=0.49, P=0.485). The positive rate of SFB was 66% (33/50) in the rotavirus enteritis group and 75% (41/55) in the control group, with no statistically significant (χ2=0.56, P=0.454). In the children ≤2 years old, the SFB positivity rate was 69% (24/35) in the rotavirus
enteritis group and 89% (31/35) in the control group, with a statistically significant difference (χ2=4.16, P=0.041). However, in the children >2-5 years old, no statistically significant difference was observed, with the positive rate of SFB being 9/15 in the rotavirus enteritis group and 50% (10/20) in the control group (P=0.734). Pearson correlation analysis revealed a negative correlation between rotavirus infection and SFB positivity (r=-0.87,P<0.001). As the concentration of the p3340 specific protein increased, the luminescence intensity of the luciferase in the Vero cells, which were suitable for cultivating rotavirus, exhibited a decreasing trend (F=4.17, P=0.001). Conclusions: SFB colonization in infants less than 2 years old is associated with a reduced risk of rotavirus infection. Cloning of specific SFB functional protein p3340 neutralizes rotavirus infection of Vero cells, and this mechanism of targeting rotavirus infection differs from the common antiviral mechanism.
目的: 探讨肠道分节丝状菌(SFB)定植与轮状病毒感染风险的关系及SFB抵御轮状病毒感染的可能机制。 方法: 病例对照研究。选择在浙江大学医学院附属儿童医院门诊因腹泻经粪便检测轮状病毒阳性的0~5岁患儿50例为研究对象,即轮状病毒性肠炎组,并以非胃肠道疾病、非感染性疾病的外科疾病患儿55例为对照组,年龄、性别组成与轮状病毒性肠炎组相匹配。提取粪便菌群的DNA,通过实时荧光定量PCR分析测定SFB,将轮状病毒性肠炎组及对照组患儿分别按照年龄和性别分组,分析SFB的阳性率在不同组间的差异,并进一步比较分析这两组患儿在≤2岁组及>2~5岁年龄组SFB阳性率的差异。通过p3340蛋白与轮状病毒进行中和试验,确定Vero细胞轮状病毒感染率与p3340浓度之间的关系。组间比较采用χ2检验或Fisher确切概率法。 结果: 轮状病毒性肠炎组患儿50例,年龄(1.7±0.9)岁,对照组患儿55例,年龄(1.8±1.1)岁。轮状病毒性肠炎组患儿SFB 的阳性率在各个年龄中呈递减分布,其中≤1岁组最高,为10/14,>1~2岁组为67%(14/21),>2~5岁组为9/15,差异无统计学意义(P=0.867);对照组患儿≤1岁组SFB阳性率为12/15,>1~2岁组为95%(19/20),>2~5岁组为50%(10/20),差异有统计学意义(P=0.004)。轮状病毒性肠炎组患儿男童SFB阳性率为74%(20/27),女童为56%(13/23),差异无统计学意义(χ2=1.71,P=0.192);对照组患儿男童SFB阳性率为79%(22/28),女童为70%(19/27),差异无统计学意义(χ2=0.49,P=0.485)。轮状病毒性肠炎组SFB阳性率66%(33/50),对照组为75%(41/55),差异无统计学意义(χ2=0.56,P=0.454)。在≤2岁患儿中,轮状病毒性肠炎组SFB阳性率69%(24/35),对照组为89%(31/35),差异有统计学意义(χ2=4.16,P=0.041);在>2~5岁患儿中,轮状病毒性肠炎组SFB阳性率为9/15,对照组为50%(10/20),差异无统计学意义(P=0.734)。经Pearson相关性分析,随着SFB阳性率的增加,轮状病毒的感染率呈下降趋势(r=-0.87,P<0.001)。随着p3340特异蛋白浓度的增加,适合培养轮状病毒的Vero细胞荧光素酶的发光强度呈下降趋势(F=4.17,P=0.001)。 结论: 2岁以内婴幼儿肠道SFB定植与降低轮状病毒感染风险相关;克隆特定SFB功能蛋白p3340可以中和轮状病毒感染Vero细胞,且这种针对轮状病毒感染的机制可能不同于常见的抗病毒机制。.