INTENDED USE

The HAV IgG/IgM Rapid Test is a lateral flow chromatographic immunoassayfor the qualitative detection and differentiation of antibodies (IgG and IgM)to Hepatitis A virus (HAV) in human serum, plasma or whole blood. It isintended to be used as a screening test by professionals and provide apreliminary test result to aid in the diagnosis of HAV infection.

SUMMARY

First isolated in 1973, hepatitis A virus (HAV) is a non-enveloped RNA virusof the family Picornaviridae, genus Hepatovirus. Its transmission occursprimarily through serial transmissions from person to person by the fecal-oral route. However, HAV can also be contracted from contaminated water,close personal contact, sexual contact, and illicit drug use. Infection ischaracterised by rapid onset following an incubation period ofapproximately 28 days (15-50 days), which is followed by a rapid onset ofsymptoms. Signs and symptoms can include nausea, vomiting, diarrhea,dark urine, jaundice, fever, headaches, weight loss and abdominal pain. Thelikelihood of symptoms increases with age. Normally, acute illness does notlast more than two months. There is no chronic viral shedding and nochronic stage of the disease, though recurrences, acute fulminant hepatitisand other complications may occur. Anti-HAV IgM are detectable at orprior to the onset of clinical illness and decline in about 3 to 6 months. Anti-HAV IgG appear soon after IgM, persist for years after infection and conferlifelong immunity. The presence of anti-HAV IgG and the absence of anti-HAV IgM can be used to differentiate between past and current infections.IgM assays can detect antibodies in individuals recently administeredhepatitis A vaccine for a short period of time. However, lowerconcentrations detected 4 to 6 months after the onset of infection typicallydo not produce a positive test result.
The HAV IgG/IgM Rapid Test detects and differentiates anti-HAV IgG from anti-HAV IgM in human serum, plasma or whole blood after 15 minutes and can be performed by minimally-skilled personnel without the use of laboratory equipment.

PRINCIPLE

The HAV IgG/IgM Rapid Test is a lateral flow chromatographic immunoassay.The test cassette consists of: 1) a burgundy conjugate pad containing HAVantigens conjugated with colloidal gold (HAV Ag conjugates) and controlantibodies conjugated with colloidal gold, 2) a nitrocellulose membranestrip containing two test lines (M and G) and a control line (C). Mouse anti-human IgM are pre-coated on the line ‘M’, mouse anti-human IgG areprecoated on the line ‘G’ and control antibodies are pre-coated on the line(C). When an adequate volume of specimen and buffer is dispensed into thesample well (S) and buffer well (B) respectively, the specimen migrates bycapillary action along the test cassette. If anti-HAV IgM are present in the specimen, they bind to the HAV Ag conjugates. The immunocomplexes arethen captured on the membrane by the pre-coated mouse anti-human IgM,forming a burgundy line ‘M’, indicating an HAV IgM positive test result. Ifanti-HAV IgG are present in the specimen, they also bind to the HAV Agconjugates. The immunocomplexes are then captured on the membrane bythe pre-coated mouse anti-human IgG, forming a burgundy line ‘G’,indicating an HAV IgG positive test result. The absence of both test lines (Mand G) suggests a negative result.
The test contains an internal control (C) which should always exhibit a burgundy line of the immunocomplex of control line antibodies, regardless of the colour development of the test lines (M and G). Otherwise, the test result is invalid and the specimen should be retested with another test cassette.