SeroCP Semi-quantitative IgG ELISA Assay

Additional Information

Assay Background

Chlamydia pneumoniae (TWAR-183) is an emerging infectious agent with a spectrum of clinical manifestations, including upper and lower respiratory tract infections. The majority of C.pneumoniae infections are mild and asymptomatic yet, may cause serious diseases, such as pharyngtitis, sinusitis, acute bronchitis and community acquired pneumonia. Undetected and untreated infection may lead to prolonged and persistent disease. Recent data indicates a possible association between C.pneumoniae infection and chronic diseases. Seroprevalence of C.pneumoniae among children is low but increases sharply until middle age, where after it remains high (>50%).

Difficulties in sample collection and inaccessibility of the infected site seriously affect the usefulness of direct detection methods. Therefore, serological testing is routinely used and serves as a non-invasive tool in identification of both distal and chronic chlamydial infections, where direct detection methods are rarely efficient. In addition, the presence of certain antibody types may also indicate the state of the disease. Primary chlamydial infection is characterized by a predominant IgM response within 2 to 4 weeks and a delayed IgG and IgA response within 6 to 8 weeks. After acute C.pneumoniae infection, IgM antibodies are usually lost within 2 to 6 months, IgG antibody titers usually decrease slowly; whereas IgA antibodies tend to disappear rapidly. When primary chlamydia infection is suspected, the detection of IgM is highly diagnostic. However, in recurrent or chronic infections the prevalence of IgM is low and therefore absence of IgM does not necessarily exclude on-going infection. In reinfection, IgG and IgA levels rise quickly, often in one to two weeks.

IgA antibodies have shown to be a reliable immunological marker of primary, chronic and recurrent infections. These antibodies usually decline rapidly to baseline levels following treatment and eradication of the chlamydia infections. The persistence of elevated IgA antibody titers is generally considered as a sign of chronic infection. IgG antibodies persist for long periods and decline very slowly. Therefore, the presence of IgG antibodies is mainly indicative of a chlamydia infection at an undetermined time. However, a four-fold rise in IgG or high levels of IgG antibodies may indicate an on-going chronic infection.

SeroCP™ Quant is an ELISA based assay in which purified elementary bodies of C.pneumonaie (TWAR-183) are used as antigens to detect the antibody response in humans. For complete diagnosis of current, chronic or past infections, it is recommended to determine IgG, IgM and IgA antibodies to C.pneumoniae.