Recombinant Enterovirus 71 VP2 (aa 70-323) [His]

Virus-encoded proteases play diverse roles in the efficient replication of enterovirus 71 (EV71), which is the causative agent of human hand, foot, and mouth disease (HFMD). However, it is unclear how host proteases affect viral proliferation. Here, we designed activity-based probes (ABPs) based on an inhibitor of the main EV71 protease (3Cpro), which is responsible for the hydrolysis of the EV71 polyprotein, and successfully identified host candidates that bind to the ABPs. Among the candidates, the host cysteine protease autophagy-related protein 4 homolog B (ATG4B), a key component of the autophagy machinery, was demonstrated to hydrolytically process the substrate of EV71 3Cpro and had activity comparable to that of the viral protease. Genetic disruption of ATG4B confirmed that the enzyme is indispensable for viral proliferation in vivo. Our results not only further the understanding of host-virus interactions in EV71 biology but also provide a sample for the usage of activity-based proteomics to reveal host-pathogen interactions. IMPORTANCE Enterovirus 71 (EV71), one of the major pathogens of human HFMD, has caused outbreaks worldwide. How EV71 efficiently assesses its life cycle with elaborate interactions with multiple host factors remains to be elucidated. In this work, we deconvoluted that the host ATG4B protein processes the viral polyprotein with its cysteine protease activity and helps EV71 replicate through a chemical biology strategy. Our results not only further the understanding of the EV71 life cycle but also provide a sample for the usage of activity-based proteomics to reveal hostpathogen interactions.

Influenza A virus (IAV), influenza B virus (IBV), enterovirus 71 (EV71), and coxsackievirus A16 (CVA16) are common pathogens for viral infection in children. In order to investigate the epidemiology of these four viral infections in the central region of Zhejiang province, China, 10,638 respiratory secretion samples previously tested for IAV and IBV, and 6427 whole blood samples previously tested for EV71 and CVA16 detection were analyzed retrospectively. The present data shows that viral infections with these four viruses featured with distinct seasonal patterns. Both IAV and IBV infections more frequently occurred in winter, while infections with the two enteroviruses peaked in summer with high positive rates in other months. The most susceptible ages for IAV, IBV, EV71, and CVA16 were 2-7 years old, 4-6 years old, 1-3 years old, and 1-2 years old, respectively. It was recommended that children in the central region of Zhejiang Province should be vaccinated for influenza by the end of October every year, especially between the ages of 2 and 7 years old and children in age from 1 to 3 years old should be paid more attention all year round for EV71 and CVA16 infection. Moreover, the female gender appeared to be a risk factor only for IBV infection, while CVA16 inflicted more infection in young children. This study revealed that season, age, and gender should be taken into consideration when devising vaccination schedules for children in the central region of Zhejiang.