Journal of Medical Virology 83:1783–1791 (2011) Partial Protection Against Enterovirus 71 (EV71) Infection in a Mouse Model Immunized With Recombinant Newcastle Disease Virus Capsids Displaying the EV71 VP1 Fragment Wei-Choong Ch’ng, 1 Eric J. Stanbridge, 2 Kien-Chai Ong, 3 Kum-Thong Wong, 4 Khatijah Yusoff, 1 and Norazizah Shafee 1 * 1 Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Malaysia 2 Department of Microbiology and Molecular Genetics, School of Medicine, University of California, Irvine, California 3 Department of Molecular Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia 4 Department of Pathology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia Enterovirus 71 (EV71) infection may cause se- vere neurological complications, particularly in young children. Despite the risks, there are still no commercially available EV71 vaccines. Hence, a candidate vaccine construct, contain- ing recombinant Newcastle disease virus capsids that display an EV71 VP1 fragment (NPt-VP1 1-100 ) protein, was evaluated in a mouse model of EV71 infection. Previously, it was shown that this protein construct provoked a strong immune response in vaccinated adult rabbits. That study, however, did not address the issue of its effectiveness against EV71 infec- tion in young animals. In the present study, EV71 viral challenge in vaccinated newborn mice resulted in more than 40% increase in survival rate. Significantly, half of the surviving mice fully recovered from their paralysis. Histo- logical analysis of all of the surviving mice revealed a complete clearance of EV71 viral antigens from their brains and spinal cords. In hind limb muscles, the amounts of the antigens detected correlated with the degrees of tissue damage and paralysis. Findings from this study provide evidence that immunization with the NPt-VP1 1-100 immunogen in a newborn mouse model confers partial protection against EV71 infection, and also highlights the importance of NPt-VP1 1-100 as a possible candidate vaccine for protection against EV71 infections. J. Med. Virol. 83:1783–1791, 2011. ß 2011 Wiley-Liss, Inc. KEY WORDS: enterovirus 71 infection; vac- cine; protection INTRODUCTION Among the enteroviruses, human enterovirus 71 (EV71) is one of the most important viral pathogens in children [Chang et al., 2007]. Although it mainly causes self-limiting hand, foot, and mouth disease (HFMD) [Ding et al., 2009], it may be complicated by severe neurological complications such as encephalo- myelitis, acute flaccid paralysis, aseptic meningitis, and cerebellar ataxia [Chang et al., 2007; Wong et al., 2008]. The virus is transmitted by the fecal-oral route [Ooi et al., 2007], oral–oral route, or via droplets [Chang et al., 2007], and has high household trans- mission rates among children [Chang et al., 2004; Abzug, 2009]. An increasing number of fatal cases were reported recently, especially in the Asia-Pacific region [Cardosa et al., 1999; Chan et al., 2000, 2003; Shinohara et al., 2001; McMinn, 2002; Herrero et al., 2003]. During the 2007–2009 outbreaks in China, hundreds of deaths were reported, mostly in young children [Li et al., Additional supporting information may be found in the online version of this article. Grant sponsor: Malaysian Ministry of Science, Technology, and Innovation (partial support); Grant number: 04-01-09- 0802RU, 07-05-IFN-MEB006, 07-05-MGI-GMB009. *Correspondence to: Norazizah Shafee, Department of Micro- biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang 43400, Malaysia. E-mail: nshafee@biotech.upm.edu.my Accepted 4 July 2011 DOI 10.1002/jmv.22198 Published online in Wiley Online Library (wileyonlinelibrary.com). ß 2011 WILEY-LISS, INC.