Seoul orthohantavirus is a member of the Orthohantavirus family of rodent-borne viruses and can cause Hantavirus hemorrhagic fever with renal syndrome. It is an Old World hantavirus; a negative sense, single-stranded, tri-segmented RNA virus. Seoul virus is found in Rattus species rats, most commonly Rattus norvegicus, but occasionally Rattus rattus. Rats do not show physiological symptoms when carrying the virus, but humans can be infected through exposure to infectious body fluids, exposure to aerosolized rat feces, or bites from infected rats. There is no evidence of human-to-human transmission of SEOV. Seoul virus was first described by Dr. Lee Ho-Wang, a Korean virologist. As the infection was first found in an apartment in Seoul, the virus was named "Seoul Virus".
SEOV, along with all other hantaviruses, is a negative sense, single-stranded RNA virus. Its genome has three different segments: S, M, and L. The virus is pleomorphic, having various shapes, but often is seen as spherical, with its two surface glycoproteins arranged in rows. Inside this sphere, the three RNA segments are arranged as circles, coated in the virus' N protein and attached to the L protein. The 5' and 3' ends of the genome segments match up, creating a panhandle structure. This base pairing occurs in all hantavirus species, with the panhandle structure and sequence being unique to each particular species, of course with some similarities and overlap between species, including an eight nucleotide consensus sequence.
Viral proteins
There are four major viral proteins, the two surface glycoproteins, the nucleocapsid protein, and the viral polymerase. The Gn and Gc proteins exist on the surface of the mature virus as spikes in highly ordered rows, with each spike having for Gn/Gc heterodimers. Interactions between the spikes are thought to cause viral budding into the Golgi apparatus. These surface glycoproteins are also responsible for the attachment of the virus to its target host cell. Gn and Gc spikes attach to β3 integrins and co-receptors on the target cell surface.
Transmission
Rodent Populations
Human Populations
Epidemiology
Most human infections are recorded in Asia. Human infections account for ~25% of cases of hemorrhagic fever with renal syndrome in Asia. R. norvegicus rodents are found in urban areas worldwide, meaning that SEOV and HFRS are also found globally in human populations in urban areas. As of 2015 the virus has been found in wild rats in the Netherlands, and in both rodents and humans in England, Wales, France, Belgium, and Sweden. Rats in New York City are also known reservoirs. An outbreak of Seoul virus infected eleven people in the U.S. states of Illinois, Indiana and Wisconsin from December 2016 to February 2017. Individuals who operated a home-based rat-breeding facility in Wisconsin became ill and were hospitalized. The ill individuals had purchased rats from animal suppliers in Wisconsin and Illinois. Investigators traced the infection to two Illinois ratteries and identified six additional people who tested positive for Seoul virus. All these individuals recovered. Further investigation by the Centers for Disease Control and Prevention revealed that potentially infected rodents may have traveled to the states of Alabama, Arkansas, Colorado, Illinois, Indiana, Iowa, Louisiana, Michigan, Minnesota, Missouri, North Dakota, South Carolina, Tennessee, Utah, and Wisconsin. Cases were also reported in Ontario in February 2016.
Clinical features
In humans, Seoul virus causes hemorrhagic fever with renal syndrome, along with other Old World hantaviruses. Although New World hantaviruses typically cause hantavirus pulmonary syndrome, either disease can involve the patient's kidneys or lungs. The patient will develop high grade fever, sweating, chills, abdominal pain, joint pain, red eye, nausea, vomiting, one or multiple rash and/or a headache. The symptoms can appear quickly, the patient will suffer from severe symptoms which may lead to death. To prevent from contracting this virus, avoid contact with wild rats and only adopt pet rats from renown sources who have tested their rats by serology in order to confirm their colony does not carry this virus. Proof of testing should be public and offered to anyone who asks for it.
SEOV in Rodents
Seoul virus is known to be found primarily in Rattus norvegicus, but has also been seen in Rattus rattus populations. Traditionally, it has been thought that each virus in the hantavirus genus is highly specific to a single rodent host species, but this idea is being challenged. Rattus species rodents do not show symptoms of infection with SEOV.
