Multiplex PCR−Based Next-Generation Sequencing and Global Diversity of Seoul Virus in Humans and Rats

Seoul virus (SEOV) poses a worldwide public health threat.This virus, which is harbored by Rattus norvegicus and R. rattus rats, is the causative agent of hemorrhagic fever with renal syndrome (HFRS) in humans, which has been reported in Asia, Europe, the Americas, and Africa.Defining SEOV genome sequences plays a critical role in development of preventive and therapeutic strategies against the unique worldwide hantavirus.We applied multiplex PCR-based next-generation sequencing to obtain SEOV genome sequences from clinical and reservoir host specimens.Epidemiologic surveillance of R. norvegicus rats in South Korea during 2000-2016 demonstrated that the serologic prevalence of enzootic SEOV infections was not significant on the basis of sex, weight (age), and season.Viral loads of SEOV in rats showed wide dissemination in tissues and dynamic circulation among populations.Phylogenetic analyses showed the global diversity of SEOV and possible genomic configuration of genetic exchanges.H antaviruses (order Bunyavirales, family Hantaviri- dae, genus Orthohantavirus) pose a worldwide public health threat and are the causative agents of hemorrhagic fever with renal syndrome (HFRS) in Eurasia and hantavirus pulmonary syndrome in the Americas (1).HFRS is caused mainly by Old World hantaviruses, such as Hantaan virus (HTNV), Seoul virus (SEOV), Dobrava-Belgrade virus, and Puumala virus, that are transmitted to humans by inhalation of dust contaminated with rodent excreta (saliva, urine, and feces) or bite by an infected rodent.Annually, 150,000 cases of HFRS are reported (case-fatality rate range <1%-15%) (2).Clinical signs and symptoms include headache, myalgia, abdominal and back pain, nausea, vomiting, diarrhea, proteinuria, thrombocytopenia, hemorrhage, and renal failure (3).The typical disease course consists of 5 phases: febrile, hypotensive, oliguric, diuretic, and convalescent: the phases vary in length from several hours to several days.A difficulty in diagnosis is the extensive incubation period from the time of exposure to the onset of symptoms, which might be as long as 50 days.There are no effective vaccines or antiviral agents against hantavirus infection.SEOV has a negative-sense, single-stranded, tripartite RNA genome (4).The large (L) segment encodes an RNAdependent RNA polymerase, the medium (M) segment encodes 2 membrane glycoproteins (Gn and Gc), and the small (S) segment encodes a nucleoprotein.Brown rats (Rattus norvegicus) and black rats (R. rattus) are the primary reservoir hosts of SEOV and have a worldwide distribution (5,6).SEOV infections have been reported in Asia, Europe, the Americas, and Africa (7-12).HFRS caused by SEOV is responsible for 25% of clinical cases and is a mild form with a case-fatality rate of <1% in Asia (13).Recently, an outbreak of SEOV-induced HFRS was reported in the United Kingdom among rat owners, breeders, and distributors of the pet animal market (14).In the United States, outbreaks of SEOV infections occurred in 11 states in 2017; there were 17 confirmed SEOV-infected patients (15,16).SEOV was identified in New York, New York, and is considered an urban public health threat (17).Whole-genome sequencing of SEOV is a prerequisite for tracking SEOV infections and evaluating disease risks for development and implementation of preventive and therapeutic strategies.Acquisition of viral genome sequences plays a critical role in surveillance, identification, and risk mitigation of outbreaks of virus infection (18).Nextgeneration sequencing (NGS) is a potent tool for defining Multiplex PCR-Based Next-Generation Sequencing and Global Diversity of Seoul Virus in Humans and Rats