“芪优能”对感染猪繁殖与呼吸综合征病毒(PRRSV)仔猪免疫功能及病理损伤的影响

Effects of′QiYouNeng′on Immune Function and Pathological Damage of Piglets Infected with PRRSV

[目的]研究黄芪全成分提取物“芪优能”对感染猪繁殖与呼吸综合征病毒(porcine reproductive and respiratory syndrome virus,PRRSV)断奶仔猪免疫功能和病理损伤的影响。[方法]选取呈PRRSV阳性的28日龄断奶仔猪32头,随机分为组Ⅰ、组Ⅱ、组Ⅲ、组Ⅳ,每组8只。试验周期42 d,在试验第1周和第5周,组Ⅰ、组Ⅱ、组Ⅲ、组Ⅳ基础日粮中分别添加0、200、500、1000 g/t的“芪优能”。试验结束后第1天,前腔静脉采血,采用实时荧光定量RT-PCR测定各组仔猪血清中PRRSV的病毒载量,应用ELISA法检测血清中免疫球蛋白(IgG、IgA、IgM)和细胞因子(IL-2、TNF-α、IFN-γ)含量;每组剖杀3头仔猪,采集肺脏、肺门淋巴结和脾脏组织样本,制备石蜡切片,利用HE染色法、Masson三色染色法和免疫荧光双重标记染色法观察病理组织学变化。[结果]与组Ⅰ相比,组Ⅱ、组Ⅲ、组Ⅳ仔猪血清中的PRRSV拷贝数均极显著(P<0.01)降低,组Ⅲ和组Ⅳ仔猪血清中IL-2、IFN-γ含量极显著(P<0.01)升高,组Ⅱ、组Ⅲ、组Ⅳ仔猪血清中IgG含量均极显著(P<0.01)升高,组Ⅲ和组Ⅳ仔猪血清中IgA含量分别显著(P<0.05)和极显著(P<0.01)升高。病理组织学分析显示,与组Ⅰ相比,组Ⅲ、组Ⅳ仔猪的肺脏、肺门淋巴结和脾脏损伤程度明显减弱;组Ⅱ仔猪肺脏组织的CD68阳性巨噬细胞占比显著(P<0.05)升高,组Ⅲ、组Ⅳ仔猪肺脏组织的CD68阳性巨噬细胞占比均极显著(P<0.01)升高,组Ⅲ和组Ⅳ仔猪肺脏组织的CD163阳性巨噬细胞占比极显著(P<0.01)升高,组Ⅲ、组Ⅳ仔猪肺脏组织的CD163/CD68比值极显著(P<0.01)升高。[结论]在PRRSV感染仔猪基础日粮中添加黄芪全成分提取物“芪优能”,具有降低病毒载量、增强免疫功能及减轻肺脏、脾脏、肺门淋巴结病理损伤的作用,以添加水平为1000 g/t的效果最明显。

[Objective]This study aimed to assess the effects of′QiYouNeng′,a preparation of Astragalus membranaceus extracts(whole composition),on immune function and pathological damage of the weaned piglets infected with porcine reproductive and respiratory syndrome virus(PRRSV).[Method]A total of 32 PRRSV-positive 28-day-old weaned piglets were selected and randomly divided into GroupsⅠ,Ⅱ,ⅢandⅣ,with 8 piglets in each group.The experiment period was 42 days.In the first and fifth weeks of the experiment,GroupsⅠ,Ⅱ,ⅢandⅣfed the basal diets supplemented with 0,200,500 and 1000 g/t of′QiYouNeng′,respectively.On the first day after the end of the experiment,blood samples were collected from anterior venae cavae.Real-time fluorescence quantitative RT-PCR assay was used to determine the serum nucleic acid loads of PRRSV,and ELISA assay was employed to measure the serum levels of immunoglobulins(IgG,IgA and IgM)and cytokines(IL-2,TNF-αand IFN-γ).Three piglets were chosen from each group and were dissected.Tissue samples of lungs,pulmonary hilar lymph nodes and spleens were collected and embedded in paraffin sections.Pathohistological changes were observed using HE staining,Masson′s trichrome staining and immunofluorescence double-labeling staining.[Result]Compared with groupⅠ,the serum PRRSV copy number in groupsⅡ,ⅢandⅣwas extremely significantly(P<0.01)lower,the serum levels of IL-2 and IFN-γin groupsⅢandⅣwere extremely significantly(P<0.01)higher,the serum levels of IgG in groupsⅡ,ⅢandⅣwere extremely significantly(P<0.01)elevated,and the serum levels of IgA in groupsⅢandⅣwere significantly(P<0.05)and extremely significantly(P<0.01)increased,respectively.Pathohistological analysis demonstrated that in comparison to groupⅠ,the damages of lungs,pulmonary hilar lymph nodes and spleens in groupsⅢandⅣwere obviously alleviated;significantly(P<0.05)as well as extremely significantly(P<0.01)elevated ratios of CD68 positive macrophages in lung tissues were observed in groupⅡas well as groupsⅢandⅣ,respectively;groupsⅢandⅣhad extremely significantly(P<0.01)higher ratios of CD163 positive macrophages in lung tissues and CD163/CD68.[Conclusion]Dietary supplementation of′QiYouNeng′in the PRRSV-infected piglets exhibited the effects of reducing serum PRRSV load,enhancing immune function,and alleviating pathological damages of lung,spleen and pulmonary hilar lymph nodes,and the most obvious effect was achieved at the level of 1000 g/t.