Liao ning virus (LNV) is a

virus A virus is a submicroscopic infectious agent that replicates only inside the living Cell (biology), cells of an organism. Viruses infect all life forms, from animals and plants to microorganisms, including bacteria and archaea. Viruses are ...

belonging to the genus ''

Seadornavirus ''Seadornavirus'' is a genus of viruses, in the order ''Reovirales'', in the family ''Sedoreoviridae''. Human, cattle, pig, and mosquitoes serve as natural hosts. There are three species in this genus: Banna virus (BAV), Kadipiro virus, and Li ...

'' within the family ''

Sedoreoviridae ''Sedoreoviridae'' (''sedo'' = smooth) is a family of the ''Reovirales'' order of viruses. Viruses in this family are distinguished by the absence of a turreted protein on the inner capsid to produce a smooth surface. Taxonomy The family contain ...

'', a family of segmented, non-enveloped, double-stranded RNA viruses. LNV was first discovered in '' Aedes dorsalis'' populations in the

Liaoning ) , image_skyline = , image_alt = , image_caption = Clockwise: Mukden Palace in Shenyang, Xinghai Square in Dalian, Dalian coast, Yalu River at Dandong , image_map = Liaoning in China (+all claims hatched).svg , ...

province of the

People's Republic of China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

in 2006 from mosquito samples obtained in 1997. Its geographic distribution was previously thought to be limited to China, but it has since been found in mosquito populations in

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

. In addition to ''Aedes dorsalis'', LNV has been isolated from ''

Culex ''Culex'' or typical mosquitoes are a genus of mosquitoes, several species of which serve as vectors of one or more important diseases of birds, humans, and other animals. The diseases they vector include arbovirus infections such as West Nil ...

'' species.

Virology

LNV's

genome A genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding genes, other functional regions of the genome such as ...

is about 20,700

base pair A base pair (bp) is a fundamental unit of double-stranded nucleic acids consisting of two nucleobases bound to each other by hydrogen bonds. They form the building blocks of the DNA double helix and contribute to the folded structure of both DNA ...

s in length, and is segmented into 12 parts, with each segment having a major

open reading frame In molecular biology, reading frames are defined as spans of DNA sequence between the start and stop codons. Usually, this is considered within a studied region of a prokaryotic DNA sequence, where only one of the six possible reading frames ...

that encodes for proteins VP1–12. VP10, believed to be a

capsid A capsid is the protein shell of a virus, enclosing its genetic material. It consists of several oligomeric (repeating) structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or m ...

protein, is responsible for determining the

serotype A serotype or serovar is a distinct variation within a species of bacteria or virus or among immune cells of different individuals. These microorganisms, viruses, or Cell (biology), cells are classified together based on their shared reactivity ...

, of which two serotypes have been identified to date. VP1 is most likely the

RNA-dependent RNA polymerase RNA-dependent RNA polymerase (RdRp) or RNA replicase is an enzyme that catalyzes the self-replication, replication of RNA from an RNA template. Specifically, it catalyzes synthesis of the RNA strand Complementarity (molecular biology), compleme ...

, VP3 is likely guanylyltransferase, a

capping enzyme A capping enzyme (CE) is an enzyme that catalyzes the attachment of the 5' cap to messenger RNA molecules that are in the process of being synthesized in the cell nucleus during the first stages of gene expression. The addition of the cap occurs ...

, VP7 shows similarities to protein

kinase In biochemistry, a kinase () is an enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules to specific substrates. This process is known as phosphorylation, where the high-energy ATP molecule don ...

s, and VP11 matches the dsRNA-binding proteins of other seadornaviruses. LNV is unique among seadornaviruses in that it is the only seadornavirus known to replicate in

mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...

ian cells. The most recent common ancestor of LNV isolates from China is estimated to have been in the year 318. Genetic analysis indicates that LNV populations were relatively stable for centuries but declined significantly in the late 1980s and early 1990s, before growing again starting in the late 1990s. LNV evolves at about the same rate as other dsRNA viruses but at a faster pace than other

arbovirus Arbovirus is an informal name for any virus that is Transmission (medicine), transmitted by arthropod Vector (epidemiology), vectors. The term ''arbovirus'' is a portmanteau word (''ar''thropod-''bo''rne ''virus''). ''Tibovirus'' (''ti''ck-''bo ...

es. Part of LNV's genome is integrated into the ''

Aedes aegypti ''Aedes aegypti'' ( or from Greek 'hateful' and from Latin, meaning 'of Egypt'), sometimes called the Egyptian mosquito, dengue mosquito or yellow fever mosquito, is a mosquito that spreads diseases like dengue fever, yellow fever, malar ...

'' genome, indicating that LNV likely originates from Africa, where ''Aedes aegypti'' is from, and didn't leave the continent until the growth of the

shipping industry Maritime transport (or ocean transport) or more generally waterborne transport, is the transport of people (passengers or goods (cargo) via waterways. Freight transport by watercraft has been widely used throughout recorded history, as it provi ...

in the 18th and 19th centuries.

Symptoms and diagnosis

LNV is not known to cause disease in humans, but it has been investigated as a cause of

encephalitis Encephalitis is inflammation of the Human brain, brain. The severity can be variable with symptoms including reduction or alteration in consciousness, aphasia, headache, fever, confusion, a stiff neck, and vomiting. Complications may include se ...

in regions of China that experience seasonal encephalitis but are not affected by

Japanese encephalitis Japanese encephalitis (JE) is an infection of the brain caused by the Japanese encephalitis virus (JEV). While most infections result in little or no symptoms, occasional inflammation of the brain occurs. In these cases, symptoms may include he ...

. In mice, reinfection, or being infected again shortly after recovering from an initial infection, causes lethal hemorrhaging. The exact reason for this is unknown, but it does not appear to be related to any antibody-facilitating effect. An

enzyme-linked immunosorbent assay The enzyme-linked immunosorbent assay (ELISA) (, ) is a commonly used analytical biochemistry assay, first described by Eva Engvall and Peter Perlmann in 1971. The assay is a solid-phase type of enzyme immunoassay (EIA) to detect the presence o ...

(ELISA) based on the VP10 of both serotypes and a real time

reverse transcription polymerase chain reaction Reverse transcription polymerase chain reaction (RT-PCR) is a laboratory technique combining reverse transcription of RNA into DNA (in this context called complementary DNA or cDNA) and amplification of specific DNA targets using polymerase cha ...

(RT-PCR) based on genome segments 10 and 12 have been developed to identify and conduct serological surveys of LNV.

References

{{Taxonbar, from=Q16968997 Seadornaviruses