Muju virus, a novel hantavirus harboured by the arvicolid rodent Myodes regulus in Korea

Abstract

Acute-phase sera from >5 % of cases of haemorrhagic fever with renal syndrome occurring annually in Korea have been found to exhibit a fourfold or higher antibody titre to Puumala virus (PUUV) than to Hantaan virus (HTNV) by double-sandwich IgM ELISA, suggesting the existence of a PUUV-related hantavirus. Based on the phylogenetic relationships among arvicolid rodents, the royal vole (Myodes regulus) was targeted as a likely reservoir host of hantavirus. Using RT-PCR, a genetically distinct hantavirus, designated Muju virus (MUJV), was detected in lung tissue of royal voles, captured in widely separated geographical regions in Korea during 1996-2007. Pairwise analysis of the full-length S (1857 nt) and M (3634 nt) segments of MUJV indicated approximately 77 % sequence similarity with PUUV. At the amino acid level, MUJV differed from PUUV by 5.5-6.9 % (nucleocapsid) and 10.0-11.6 % (Gn and Gc envelope glycoproteins). Interstrain variation of MUJV sequences from royal voles captured in different regions suggested geographic-specific clustering. Neutralizing antibody titres against PUUV were two- to sixfold higher than to HTNV in sera of MUJV-infected Myodes regulus. Although virus isolation attempts were unsuccessful, the collective data indicate that MUJV is a distinct hantavirus species.

Fig. 1

Map of Korea, showing the six provinces (Chungcheongnam, Gangwon, Gyeonggi, Gyeongsangbuk, Jeollabuk and Jeollanam) and 13 counties (▲), where Myodes regulus voles were trapped during 1996–2007. Mt Deogyu (1614 m) and Suseongdae (1240 m), in Muju county, Jeollabuk province, located about 190 km south and 70 km east of Seoul, were two principal capture sites. The nine trapping sites in Gangwon province comprised Damte valley in Cheolwon county; Mt Gyebang (1577 m) in Hongcheon county; Mt Jeombong (1424 m), Mt Gachilbong (1241 m), Mt Hanseg (1104 m), Garibong (1519 m) and Hangyeryung (1307 m) in Inje county; Unduryeong (1089 m) in Pyungchang county; and Mt Whaag (1468 m) in Whacheon county. Other capture sites were Mt Myungseong (923 m), Mt Unbong (868 m), Gapyung, Pocheon and Yeonchon counties and Paju city in Gyeonggi province; Mt Gaya in Yesan county, Chungcheongnam province; Mt Joryeong (1017 m) in Munkyung county, Gyeongsangbuk province; and Yeongkwang county, Jeollanam province.

Fig. 2

Neighbour-joining phylogenetic trees based on the full-length S segment (a), the full-length M segment (b) and a 208 nt region (nt 1032–1239) of the S segment (c) of MUJV strains and other arvicolid rodent-borne hantaviruses, including Puumala (PUU), Tula (TUL), Khabarovsk (KHA), Isla Vista (IV), Bloodland Lake (BLLL) and Prospect Hill (PH) viruses. The phylogenetic positions of hantaviruses harboured by murid rodents, including Hantaan (HTN), Seoul (SEO), Soochong (SOO) and Dobrava (DOB) viruses, and those carried by neotomine and sigmodontine rodents, including Sin Nombre (SN), New York (NY), El Moro Canyon (ELMC), Black Creek Canal (BCC), Bayou (BAY) and Andes (AND) viruses, are also shown. Thottapalayam (TPM) virus is a prototype shrew-borne hantavirus. The numbers at each node are percentage bootstrap probabilities, as determined for 1000 iterations using PAUP version 4.0. The GenBank accession numbers for the MUJV sequences are provided in Table 2. Bars, 0.05 substitutions per site.

Fig. 3

Phylogenetic tree based on the 426 nt cytochrome b region of mitochondrial DNA sequences of arvicolid rodents, showing the phylogenetic position of Myodes regulus in relation to Myodes rufocanus, Myodes glareolus, P. subterraneus, Microtus arvalis, Microtus fortis and Microtus pennsylvanicus. The phylogenetic positions of murid rodents (Rattus norvegicus, Apodemus agrarius and Apodemus peninsulae) are included. Myodes mtDNA sequences were derived from royal voles in which MUJV sequences had been detected. The numbers at each node are percentage bootstrap probabilities, as determined for 1000 iterations using PAUP version 4.0. The GenBank accession numbers for the nine Myodes regulus mtDNA sequences are DQ138116–DQ138124.