Abstract: Available online at www.sciencedirect.com Antiviral Research 77 (2008) 150–152 Short communication Inhibition of human coronavirus 229E infection in human epithelial lung cells (L132) by chloroquine: Involvement of p38 MAPK and ERK Masakazu Kono a,b , Koichiro Tatsumi b , Alberto M. Imai a , Kengo Saito a , Takayuki Kuriyama b , Hiroshi Shirasawa a,∗ a Department of Molecular Virology, Chiba University School of Medicine, 1-8-1 Inohana, Chiba 260-8670, Japan b Department of Chest Medicine, Chiba University School of Medicine, 1-8-1 Inohana, Chiba 260-8670, Japan Received 13 July 2007; accepted 17 October 2007 Abstract The antiviral effects of chloroquine (CQ) on human coronavirus 229E (HCoV-229E) infection of human fetal lung cell line, L132 are reported. CQ significantly decreased the viral replication at concentrations lower than in clinical usage. We demonstrated that CQ affects the activation of p38 mitogen-activated protein kinase (MAPK) and extracellular signal-regulated kinase (ERK). Furthermore, p38 MAPK inhibitor, SB203580, inhibits CPE induced by HCoV-229E infection and viral replication. Our findings suggest that CQ affects the activation of MAPKs, involved in the replication of HCoV-229E. © 2007 Elsevier B.V. All rights reserved. Keywords: Coronavirus; 229E; Chloroquine; p38; MAPK; ERK Chloroquine (CQ), a diprotic weak base that increases the pH of acidic vesicles, has been used for the treatment of malaria and inflammatory diseases, such as rheumatoid arthritis. CQ has antimicrobial effects even against viruses, such as human immunodeficiency virus type 1 (HIV-1) and SARS-CoV (Sperber et al., 1993; Savarino et al., 2003; Vincent et al., 2005). However, the inhibitory effect on SARS-CoV is inactive in vivo (Barnard et al., 2006), and the detailed mechanisms underlying the antimicrobial and anti-inflammatory effects of CQ remain poorly understood. Coronavirus, an enveloped virus, enters the cytoplasm by endocytosis and matures in the membrane transport system, such as the trans-Golgi network (TGN) (Nauwynck et al., 1999; Ng et al., 2003). ER stress caused by Japanese encephalitis virus infection induces the activation of p38 mitogen-activated protein kinase (MAPK) and host cell apoptosis (Su et al., 2002). MAPKs including ERK, JNK and p38 are involved in cell death (Xia et ∗ Corresponding author. E-mail address: sirasawa@faculty.chiba-u.jp (H. Shirasawa). 0166-3542/$ – see front matter © 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.antiviral.2007.10.011 al., 1995) play a crucial role in infection of coronaviruses, such as mouse hepatitis virus and SARS-CoV (Banerjee et al., 2002; Kopecky-Bromberg et al., 2006). CQ inhibits the activation of p38 MAPK and cytokine production caused by CpG DNA (Yi and Krieg, 1998). ERK, another MAPK associated with cell proliferation (Xia et al., 1995), is also affected by virus infection and CQ (Pleschka et al., 2001; Weber et al., 2002). In this study, we examined the correlation between CQ and the activation of p38 MAPK and ERK in human coronavirus 229E (HCoV-229E) infection, and demonstrated the involvement of p38 MAPK in the replication of HCoV-229E. To examine the effect of CQ on the viral replication, virus in the supernatants was quantified by measuring the HCoV-229E RNA by reverse transcription (RT) realtime PCR. RNA from culture supernatants was extracted by using the QIAamp Viral RNA Mini Kit (QIAGEN) according to manufacturer’s instructions and used for..