凡纳滨对虾（Litopenaeus vannamei）肝胰腺坏死症发病范围广、致死率高，其致病机理不明。基于文献和前期工作，我们推测水质恶化诱导条件病原菌致病性、胁迫并改变对虾肠道菌群，最终病原菌成功定殖导致病害。本项目拟结合Illumina测序和病原菌芯片（PathoChip）技术监测对虾养殖和肝胰腺坏死症病害过程中肠道菌群和毒力基因组成。基于微生态平衡理论探究水质/有毒藻-浮游细菌-毒力基因-肠道菌群-病害严重程度间相互关系。网络互作分析鉴定关键的致病毒力基因及环境诱因；多毒力基因确定潜在病原菌，预测其培养基配方选择性分离。模拟发病环境和多病原菌侵染时序特征，回复侵染验证。追根溯源揭示病原菌从水体到对虾肠道中的传播规律、如何突破宿主免疫和肠道共生菌的定殖拮抗；探究肝胰腺坏死症的微生态学机理。同时，尝试建立以qPCR检测的病害指示毒力基因相对丰度为自变量，定量预测对虾病害风险的技术。

Shrimp (Litopenaeus vannamei) hepatopancreas necrosis syndrome (HPNS) is characterized of wide range of morbidity and high mortality rate, while its pathogenesis is currently unclear. Based on available literatures and our previous works, we hypothesize that deteriorative water quality induces the virulence of opportunistic pathogens, stresses shrimp and disrupts the gut microbiota, which cumulatively facilitates the invasion of pathogens, thereby resulting in disease outbreak. This proposal will integrate Illumina sequencing and PathoChip techniques to track the dynamics of gut bacterial community over shrimp development stages and HPNS progression. Based on the microecological equilibrium theory, we will explore the interplay among water quality, toxic algae, bacterioplankton communities, virulence genes, shrimp gut microbiotas and HPNS severity, thereby identifying key virulence genes that facilitate the pathogenicity of pathogens and the underlying driving environmental factors. Candidate pathogens would be primarily identified via multiple key virulence genes, which are isolated by using the predicted media given their 16S rDNA gene sequences. Further, we validate the causal pathogens by stimulating the external conditions and re-introduced infections. Tracing the source to track the dispersal route of causal pathogens from rearing water to shrimp, and uncover how the pathogens overcome the barriers imposed by the shrimp gut commensals and immunity. Towards above findings, the pathogenesis of shrimp HPNS will be illustrated from a microecological perspective. After ruling out the baseline of gut bacterial virulence genes as shrimp aged, we intend to identify disease-discriminatory virulence genes that characteristic of shrimp HPNS. Further, we attempt to establish a strategy that employs the relative abundances of disease-discriminatory virulence genes (assayed by qPCR) serve as independent variables, for quantitatively predicting the incidences of shrimp HPNS.