INTENDED USE

Enterovirus antigen test is a coloured chromatographic immunoassay for the qualitative detection of Enterovirus in stool samples. Enterovirus antigen test offers a simple and a highly sensitive screening assay to make a presumptive diagnosis of Enterovirus infection.

SUMMARY

Enterovirus belongs to the Picornaviridae family and are the smallest, non-enveloped viruses known to infect both humans and animals. The spread of enteroviral infections is mainly by the faecal-oral and oral-oral route, but also through direct contact with secretions from ophthalmic and dermal lesions. Enteroviruses are single-stranded RNA viruses. Water, food and soil contaminated by infected faeces are an exogenous infection source which creates many opportunities for the transfer of the infection, and cause an epidemic outbreak in a short period of time. The average incubation period for enteroviral contagious is from 3–10 to 30 days.
The virus, after replicating and breaking the gastrointestinal tract barrier, is transmitted via the blood stream to every organ of the body. Enterovirus reveals tropism towards organs like the heart, skin, and in particular the central nervous system. It has been proved that infected people excrete large quantities of the virus in faeces for a period of even 16 weeks.
Traditional division organizes this taxonomic group into the subgenera polioviruses, coxackieviruses (group A, B), echoviruses and a group of Enterovirus marked according to their serotype number (66–71 and newly identified 73–75, 77, 78). In 2003, the International Committee on Taxonomy of Viruses created a new taxonomy classification. Enterovirus henceforth was divided into 5 groups of species based on their molecular properties (HEV-A, HEV-B, HEV-C, HEV-D and poliovirus).

PRINCIPLE

Enterovirus is based on the principle of a qualitative immunochromatographic assay for the determination of Enterovirus (VP1 peptide) in stool samples.
The strip consists of a nitrocellulose membrane pre-coated with mouse monoclonal antibodies on the test line (T), in the results window, against Enterovirus and with rabbit polyclonal antibodies, on the control line (C), against a specific protein. The label/sample absorbent pad is sprayed with test label solution (mouse monoclonal antibodies anti-Enterovirus) conjugated to red polystyrene latex and control label solution (specific binding protein) conjugated to green polystyrene latex, forming coloured conjugate complexes.
If the sample is positive, the antigens of the diluted sample react with the red-coloured conjugate complex (anti-Enterovirus monoclonal antibodies-red polystyrene microspheres), which was previously pre-dried on the absorbent pad. The mixture then moves upward on the membrane by capillary action. As the sample flows through the test membrane, the binding conjugate complexes migrate. The anti-Enterovirus antibodies present on the membrane (test line) capture the coloured conjugate and the red line will be visible. This band is used to interpret the result.
If the sample is negative, there is no Enterovirus antigens presence and yet, the antigens may be present in a concentration lower than the detection limit value, for which the reaction will not take place with the red-coloured conjugate complex. The anti-Enterovirus antibodies present on the membrane (test line) will not capture the antigen-red-coloured conjugate complex (not formed), for which the red line will not appear. Whether the sample is positive or not, the mixture continues to move across the membrane to the immobilized specific antibodies placed in the control line. The anti-specific protein antibodies present on the membrane will capture control green-conjugate complex and the control line will always appears. The presence of this green line serves as: 1) verification that sufficient volume is added, 2) that proper flow is obtained and 3) an internal control for the reagents.