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Rotavirus Dipstick and Cassette
Rotavirus Dipstick and Cassette is a rapid, qualitative, chromatographic immunoassay which detects group A rotavirus in stool specimens.

Rotavirus is a genus of double-stranded RNA virus in the family Reoviridae. It is the leading single cause of severe diarrhoea among infants and young children.  By the age of five, nearly every child in the world has been infected with rotavirus at least once. However, with each infection, immunity develops, subsequent infections are less severe, and adults are rarely affected. There are seven species of this virus, referred to as A, B, C, D, E, F and G. Rotavirus A, the most common, causes more than 90% of infections in humans.

Rotavirus is transmitted by the faecal-oral route. It infects cells that line the small intestine and produces an enterotoxin, which induces gastroenteritis, leading to severe diarrhoea and sometimes death through dehydration. Although rotavirus was discovered in 1973 and accounts for up to 50% of hospitalisations for severe diarrhoea in infants and children, its importance is still not widely known within the public health community, particularly in developing countries. In addition to its impact on human health, rotavirus also infects animals, and is a pathogen of livestock.

More than 500,000 children under five years of age die from rotavirus infection each year and almost two million more become severely ill. In the United States, rotavirus causes about 2.7 million cases of severe gastroenteritis in children, almost 60,000 hospitalisations, and around 37 deaths each year. Public health campaigns to combat rotavirus focus on providing oral rehydration therapy for infected children and vaccination to prevent the disease.

Rotaviruses are the main cause of acute gastroenteritis, especially in children under the age of two years. Rotaviruses have been identified in almost 50% of the faeces of children with gastroenteritis, responsible for 600,000-800,000 death annually. Rotavirus infections occur frequently during the winter months. Gastroenteritis from enteric viruses can be mortal in risk populations such as children, the elderly or immunosuppressed individuals. Characteristic symptoms include vomiting, hydrodiarrhoea for between 3 and 8 days, high temperature and stomach pains. Rotaviruses transferred via the faecal-oral route are eliminated in large quantities into the intestine, so that hospital-borne infections from rotaviruses are regarded very seriously, particularly in baby stations and paediatric clinics, and are difficult to control. Early and reliable detection so that rotaviruses can be recognised and further infections avoided is therefore very important.


SPECIMEN COLLECTION

Stool samples must be taken as soon as the symptoms appear. Viral particles decrease in number after one week, making the diagnosis more difficult. The samples can be stored in the refrigerator for 1 to 2 days. For longer storage they must be kept frozen at -20ºC. In this case, the sample should be totally thawed, and brought to room temperature and homogenised before testing.

STORAGE OF TEST KIT

Biocare Rotavirus Rapid Test Device can be stored at any temperature between 4-30°C. Do not freeze. The stability of the  kit under these storage conditions is 24 months. Use up the reagents as soon as possible after the kit is opened within 3 months.

HYGIENIC TESTING

The performance of the test is hygienic, after dip the stick to the tube vials, don't need touch it again.





High performance:
--High Sensitivity: 97.6%

--High Specificity: 99.3%

--Ease-to-use

--Reliable results

--Clear backgroud, longer shelf life

 Assay Procedure
1 Allow all reagents to reach room temperature before use.
2 Place 0.5-1ml of extraction buffer in a testing tube.
3 Add a sample portion of approximately 5-6 mm size (25-100mg), with a swab, a wooden applicator or a  bacteriology loop.
4 Press the applicator to the tube and rotating it at the same time. For liquid or semi-solid stools add 100 microliters of stool using an appropriate pipette.
5 Take out one strip and dip it into the small tube with the arrow pointing to the bottom.
6 Incubate the test at room temperature and read the test after 5-15 minutes.


Ordering information:
Product Code Product Description Specimen Package Size
AN1002C Rotavirus Cassette feces 25tests/kit
AN1002S Rotavirus Dipstick feces 25tests/kit

More about rotavirus:
In 1943, Jacob Light and Horace Hodes proved that a filterable agent, in the faeces of children with infectious diarrhoea, also caused scours (livestock diarrhoea) in cattle. Three decades later, preserved samples of the agent were shown to be rotavirus. In the intervening years, a virus in mice was shown to be related to the virus causing scours. In 1973, related viruses were described by Ruth Bishop in children with gastroenteritis, in Australia.

In 1974, Thomas Henry Flewett suggested the name rotavirus after observing that, when viewed through an electron microscope, a rotavirus particle looks like a wheel (rota in Latin); the name was officially recognised by the International Committee on Taxonomy of Viruses four years later. In 1976, related viruses were described in several other species of animals. These viruses, all causing acute gastroenteritis, were recognised as a collective pathogen affecting humans and animals worldwide.Rotavirus serotypes were first described in 1980, and in the following year, rotavirus from humans was first grown in cell cultures derived from monkey kidneys, by adding trypsin, (an enzyme found in the duodenum of mammals and is now known to be essential for rotavirus to replicate), to the culture medium. The ability to grow rotavirus in culture accelerated the pace of research, and by the mid-1980s the first candidate vaccines were being evaluated.

In 1998, a rotavirus vaccine was licensed for use in the United States. Clinical trials in the United States, Finland, and Venezuela had found it to be 80 to 100% effective at preventing severe diarrhoea caused by rotavirus A, and researchers had detected no statistically significant serious adverse effects. The manufacturer, however, withdrew it from the market in 1999, after it was discovered that the vaccine may have contributed to an increased risk for intussusception, a type of bowel obstruction, in one of every 12,000 vaccinated infants. The experience provoked intense debate about the relative risks and benefits of a rotavirus vaccine.In 2006, two new vaccines against rotavirus A infection were shown to be safe and effective in children.

Rotavirus A, which accounts for more than 90% of rotavirus gastroenteritis in humans, is endemic worldwide. Each year rotavirus causes millions of cases of diarrhoea in developing countries, almost 2 million resulting in hospitalisation and an estimated 611,000 resulting in death. In the United States alone, over 2.7 million cases of rotavirus gastroenteritis occur annually, 60,000 children are hospitalised and around 37 die from the results of the infection. The major role of rotavirus in causing diarrhoea is not widely recognised within the public health community, particularly in developing countries. Almost every child has been infected with rotavirus by age five. It is the leading single cause of severe diarrhoea among infants and children, being responsible for about 20% of cases, and accounts for 50% of the cases requiring hospitalisation. Boys are twice as likely to be admitted to hospital as girls.

In temperate areas, rotavirus infections occur primarily in the winter, but in the tropics they occur throughout the year; the difference is partly explained by seasonal changes in temperature and humidity. The number attributable to food contamination is unknown.

Outbreaks of rotavirus A diarrhoea are common among hospitalised infants, young children attending day care centres, and elderly people in nursing homes. An outbreak caused by contaminated municipal water occurred in Colorado in 1981. During 2005, the largest recorded epidemic of diarrhoea occurred in Nicaragua. This unusually large and severe outbreak was associated with mutations in the rotavirus A genome, possibly helping the virus escape the prevalent immunity in the population. A similar large outbreak occurred in Brazil in 1977.
Rotavirus B, also called adult diarrhoea rotavirus or ADRV, has caused major epidemics of severe diarrhoea affecting thousands of people of all ages in China. These epidemics occurred as a result of sewage contamination of drinking water. Rotavirus B infections also occurred in India in 1998; the causative strain was named CAL. Unlike ADRV, the CAL strain is endemic. To date, epidemics caused by rotavirus B have been confined to mainland China, but surveys indicate a lack of immunity to this species in the United States.

Rotavirus C has been associated with rare and sporadic cases of diarrhoea in children in many countries, and outbreaks have occurred in Japan and England

Types of rotavirus
There are seven species of rotavirus, referred to as A, B, C, D, E, F and G. Humans are primarily infected by species A, B and C, most commonly by species A. All seven species cause disease in other animals.
Within rotavirus A there are different strains, called serotypes. As with influenza virus, a dual classification system is used, which is based on two structural proteins on the surface of the virion. The glycoprotein VP7 defines G-types and the protease-sensitive protein VP4 defines P-types (see below for details on these proteins). The P-type is indicated by a number for the P-serotype and by a number in square brackets for the corresponding P-genotype. G-serotypes are similarly numbered but the G-genotype number is the same as the G-serotype. For example, the rotavirus strain Wa is defined as P1A[8]G1. Because the two genes that determine G-types and P-types can be passed on separately to offspring, various combinations occur in any one strain.

Structure
The genome of rotavirus consists of 11 unique double helix molecules of RNA which are 18,555 nucleoside base-pairs in total. Each helix, or segment, is a gene, numbered 1 to 11 by decreasing size. Each gene codes for one protein, except genes 9 and 11, which each code for two. The RNA is surrounded by a three-layered icosahedral protein capsid. Viral particles are up to 76.5 nm in diameter and are not enveloped.

Proteins
There are six viral proteins (VPs) that form the virus particle (virion). These structural proteins are called VP1, VP2, VP3, VP4, VP6 and VP7. In addition to the VPs, there are six nonstructural proteins (NSPs), that are only produced in cells infected by rotavirus. These are called NSP1, NSP2, NSP3, NSP4, NSP5 and NSP6.
 
A simplified diagram of the location of rotavirus structural proteins
At least six of the twelve proteins encoded by the rotavirus genome bind RNA.[108] The role of these proteins play in rotavirus replication is not entirely understood; their functions are thought to be related to RNA synthesis and packaging in the virion, mRNA transport to the site of genome replication, and mRNA translation and regulation of gene expression.
Structural proteins

VP1 is located in the core of the virus particle and is an RNA polymerase enzyme. In an infected cell this enzyme produces mRNA transcripts for the synthesis of viral proteins and produces copies of the rotavirus genome RNA segments for newly produced virus particles.
 
Electron micrograph of gold nanoparticles attached to rotavirus. The small dark circular objects are gold nanoparticles coated with a monoclonal antibody specific for rotavirus protein VP6.

VP2 forms the core layer of the virion and binds the RNA genome.

VP3 is part of the inner core of the virion and is an enzyme called guanylyl transferase. This is a capping enzyme that catalyses the formation of the 5' cap in the post-transcriptional modification of mRNA. The cap stabilises viral mRNA by protecting it from nucleic acid degrading enzymes called nucleases.

VP4 is on the surface of the virion that protrudes as a spike. It binds to molecules on the surface of cells called receptors and drives the entry of the virus into the cell. VP4 has to be modified by a protease enzyme (found in the gut) into VP5 and VP8 before the virus is infectious. It determines how virulent the virus is and it determines the P-type of the virus.

VP6 forms the bulk of the capsid. It is highly antigenic and can be used to identify rotavirus species. This protein is used in laboratory tests for rotavirus A infections.

VP7 is a glycoprotein that forms the outer surface of the virion. Apart from its structural functions, it determines the G-type of the strain and, along with VP4, is involved in immunity to infection.

Nonstructural viral proteins

NSP1, the product of gene 5, is a nonstructural RNA-binding protein.
NSP2 is an RNA-binding protein that accumulates in cytoplasmic inclusions (viroplasms) and is required for genome replication.
NSP3 is bound to viral mRNAs in infected cells and it is responsible for the shutdown of cellular protein synthesis.
NSP4 is a viral enterotoxin to induce diarrhoea and was the first viral enterotoxin discovered.
NSP5 is encoded by genome segment 11 of rotavirus A and in virus-infected cells NSP5 accumulates in the viroplasm.
NSP6 is a nucleic acid binding protein, and is encoded by gene 11 from an out of phase open reading frame.