CAJ | 학술논문

本实验采用单因子浓度梯度法,以添加不同质量分数(0.0%,0.5%,1.0%,2.5%,5.0%,10.0%)聚β-羟基丁酸酯(PHB)的人工配合饲料饲喂凡纳滨对虾(Litopenaeus vannamei)20 d后,对其进行白斑综合症病毒(WSSV)感染测试；利用实时荧光定量PCR技术分析PHB对凡纳滨对虾抵御WSSV侵染能力的影响,并选择最高免疫保护率(RPS)组进行不同时间点基因表达量分析。研究发现, PHB对感染WSSV对虾的存活率无显著影响(P>0.05)；但感染WSSV的对虾平均存活时间随PHB浓度上升呈现先上升后下降再上升的趋势,饲喂PHB对虾的平均存活时间均高于对照组,其中1.0% PHB浓度组对虾平均存活时间最长,且显著高于空白对照组及5.0% PHB浓度组(P<0.05)。分析各组对虾体内病毒含量,发现1.0%PHB浓度组对虾病毒含量在实验前期显著低于对照组(P<0.05)。对虾感染WSSV后,对对照组及1.0% PHB实验组对虾前48 h内6个采样时间点的超氧化物歧化酶(sod)、过氧化氢酶(cat)、谷胱甘肽过氧化物酶(gsh-px)、溶菌酶(lzm)及抗菌肽(abp)5个基因进行表达趋势分析,结果表明基因表达趋势在两组间无显著区别；投喂PHB的对虾在感染WSSV后血淋巴中sod、cat、gsh-px和lzm表达量呈现上升后下降再上升的趋势且分别在6 h、6 h、3 h、6 h达到最大值；abp在WSSV感染3 h内急速下降,随后在12 h达到最大值后又下降；另外饲喂PHB对虾体内免疫基因表达量均高于对照组。结果说明, PHB能够提高凡纳滨对虾对WSSV的抵抗力,且在一定程度上提高了对虾的免疫力。
본실험채용단인자농도제도법,이첨가불동질량분수(0.0%,0.5%,1.0%,2.5%,5.0%,10.0%)취β-간기정산지(PHB)적인공배합사료사위범납빈대하(Litopenaeus vannamei)20 d후,대기진행백반종합증병독(WSSV)감염측시；이용실시형광정량PCR기술분석PHB대범납빈대하저어WSSV침염능력적영향,병선택최고면역보호솔(RPS)조진행불동시간점기인표체량분석。연구발현, PHB대감염WSSV대하적존활솔무현저영향(P>0.05)；단감염WSSV적대하평균존활시간수PHB농도상승정현선상승후하강재상승적추세,사위PHB대하적평균존활시간균고우대조조,기중1.0% PHB농도조대하평균존활시간최장,차현저고우공백대조조급5.0% PHB농도조(P<0.05)。분석각조대하체내병독함량,발현1.0%PHB농도조대하병독함량재실험전기현저저우대조조(P<0.05)。대하감염WSSV후,대대조조급1.0% PHB실험조대하전48 h내6개채양시간점적초양화물기화매(sod)、과양화경매(cat)、곡광감태과양화물매(gsh-px)、용균매(lzm)급항균태(abp)5개기인진행표체추세분석,결과표명기인표체추세재량조간무현저구별；투위PHB적대하재감염WSSV후혈림파중sod、cat、gsh-px화lzm표체량정현상승후하강재상승적추세차분별재6 h、6 h、3 h、6 h체도최대치；abp재WSSV감염3 h내급속하강,수후재12 h체도최대치후우하강；령외사위PHB대하체내면역기인표체량균고우대조조。결과설명, PHB능구제고범납빈대하대WSSV적저항력,차재일정정도상제고료대하적면역력。
White spot syndrome (WSS), an epizootic disease, has been prevalent in cultured shrimp in China since 1992 and results in high mortality. The economic loss caused by white spot syndrome virus(WSSV) is extensive and has been harmful to shrimp aquaculture worldwide. Poly-β-hydroxybutyrate (PHB) is a polymer of the short-chain fatty acidβ-hydroxybutyrate. β-hydroxybutyric acid can promote food digestion, nutrient absorption, and protein and mineral utilization. This study was conducted to investigate the anti-WSSV effects of PHB on and relative expression of non-specific immune genes in WSSV-infected Litopenaeus vannamei. Litopenaeus vannamei were supplied with 0.0%(control group), 0.5%, 1.0%, 2.5%, 5.0%, or 10.0% PHB in artificial compound feed at a daily ration of 5.0% body weight. After WSSV challenge, survival rates, mean survival time, relative percent survival (RPS), and number of WSSV copies were compared. The relative expression of the genes that encode superoxide dismutase (sod), catalase (cat), glutathione peroxidase (gsh-px), lysozymes (lzm), and antibacterial peptides (abp) in L. vannamei were analyzed by quantitative real-time reverse transcription PCR. The results showed that there was no difference in survival rates among different treatments (P>0.05);nevertheless, the mean survival time of PHB-fed shrimp was higher than that of the control group. The mean survival time of 1.0%PHB-fed shrimp was the highest, and it was significantly higher than that of the control and 5.0%PHB-fed shrimp (P<0.05). The number of WSSV copies in the experimental individuals fed with 0.5%, 1.0%and 2.5%PHB were lower than the contral group (P<0.05). Moreover, sod, cat, gsh-px, lzm, and abp expression levels in 1.0%PHB were higher than that in the control group. The expression level of sod, cat, gsh-px, and lzm reached the acme at 6 h, 6 h, 3 h, and 6 h, respectively. After WSSV infection, abp dropped rapidly within 3 h and then steadily decreased after reaching the acme at 12 h. In addition, the gene expression levels of PHB-fed shrimps were higher than the control group. Consequently, PHB can help improve immunity and treat WSSV infections.