Cuvry Arno, Molineaux Lorane, Gozalbo-Rovira Roberto, Neyts Johan, de Witte Peter, Rodríguez-Díaz Jesús, Rocha-Pereira Joana
KU Leuven, Department of Microbiology, Immunology and Transplantation, Rega Institute, Virus-Host Interactions & Therapeutic Approaches (VITA) Research Group, Leuven, Belgium.
KU Leuven, Translationeel Onderzoek van Gastro-enterologische Aandoeningen (TARGID), Leuven, Belgium.
PLoS Pathog. 2024 Nov 27;20(11):e1012710. doi: 10.1371/journal.ppat.1012710. eCollection 2024 Nov.
Human norovirus (HuNoV) accounts for over 700 million cases of gastroenteritis annually. Episodes of HuNoV disease are characterized by vomiting and diarrhea as the two most prominent symptoms. Despite its prevalence, our understanding of the pathophysiological mechanisms triggered upon HuNoV infection is limited, mainly due to a lack of suitable animal models. Our aim was to use the recent HuNoV zebrafish larvae model to study the effect of HuNoV infection on intestinal motility and investigate whether one viral protein could act as an enterotoxin, as seen with rotavirus. We studied whether HuNoV infection affects the contraction frequency of the intestinal bulb and the posterior intestine as well as the transit time. Infection of larvae, following injection of a HuNoV GII.4-containing stool sample in the yolk, resulted in an increased contraction frequency in the intestinal bulb. A comparable effect was observed in serotonin-treated larvae, corresponding to the natural function of serotonin. The higher replication efficacy of HuNoV GII.4 likely explains why they have a more marked effect on gut motility, when compared to other genotypes. Additionally, transit time of fluorescent food was prolonged in HuNoV GII.4 infected larvae, suggesting a loss of coordination in bowel movements upon infection. To identify the proteins responsible for the effect, individual HuNoV non-structural proteins and virus-like particles (VLPs) were injected intraperitoneally (ip). VLPs carrying VP1/VP2, but not those with only VP1, induced increased contraction frequencies in the intestinal bulb in a dose-dependent manner. In conclusion, our findings suggest that the viral capsid and potentially the minor capsid protein VP2 play a crucial role in the aetiology of symptoms associated with HuNoV, potentially acting as a viral enterotoxin. This work contributes to the understanding of the pathophysiological mechanisms in HuNoV-induced disease and further attests zebrafish as a valuable HuNoV disease model.
人诺如病毒（HuNoV）每年导致超过7亿例肠胃炎病例。HuNoV疾病发作的特征是呕吐和腹泻这两种最突出的症状。尽管其流行广泛，但我们对HuNoV感染引发的病理生理机制的了解有限，主要原因是缺乏合适的动物模型。我们的目的是利用最近的HuNoV斑马鱼幼虫模型来研究HuNoV感染对肠道运动的影响，并调查是否有一种病毒蛋白能像轮状病毒那样作为一种肠毒素发挥作用。我们研究了HuNoV感染是否会影响肠球和后肠的收缩频率以及转运时间。在卵黄中注射含HuNoV GII.4的粪便样本后感染幼虫，导致肠球收缩频率增加。在经血清素处理的幼虫中观察到了类似的效果，这与血清素的自然功能相对应。与其他基因型相比，HuNoV GII.4更高的复制效率可能解释了为什么它们对肠道运动有更显著的影响。此外，在感染HuNoV GII.4的幼虫中，荧光食物的转运时间延长，这表明感染后肠道运动失去协调性。为了确定造成这种影响的蛋白质，将单个HuNoV非结构蛋白和病毒样颗粒（VLP）腹腔注射（ip）。携带VP1/VP2的VLP，而不是仅携带VP1的VLP，以剂量依赖的方式诱导肠球收缩频率增加。总之，我们的研究结果表明，病毒衣壳以及可能的次要衣壳蛋白VP2在与HuNoV相关症状的病因中起关键作用，可能作为一种病毒肠毒素发挥作用。这项工作有助于理解HuNoV诱导疾病的病理生理机制，并进一步证明斑马鱼是一种有价值的HuNoV疾病模型。
