- Complete panel for the diagnosis of Rubella with IgG, IgM and IgG Avidity testing
- The Avidity assay can be run in early stage of acute infections due to the high sensitivity of the IgG tests.
The Rubella IgG Avidity test is a chemiluminescent immunoassay (CLIA), for use on IDS automated analyzers, for determination of Avidity Index of specific IgG class antibodies directed against Rubella virus in samples of human serum or plasma (K3-EDTA, Sodium Citrate). The possibility of differentiating antibodies at high avidity from low avidity allows to supply interesting clinical information.
This assay is used as a diagnostic aid when assessing immunity status of patients related to Rubella virus infection.
Rubella is a mild exanthematous and moderately contagious disease caused by Rubella virus. The only known hosts for Rubella virus are humans and only one serotype has been identified1. The disease is transmitted human to human, via airborne droplet emission from the upper respiratory tract of active patients. The incubation is about 2 to 3 weeks.
This disease is often mild and many patients are asymptomatic. The primary symptoms are : appearance of a rash on the face which spreads to the trunk and limbs and usually fades after three days, low grade fever, swollen glands, joint pains ,headache and conjunctivitis3.
The severe syndromes happen when pregnant women are infected with Rubella virus, especially if the infection happens in the first trimester of the pregnancy. The infection can be transmitted to the fetus through placenta, and the so called congenital Rubella syndrome ( CRS ) may occur, which lead to miscarriage, prematurity or stillbirth. If the fetus survives the CRS, serious defects may occur, including blindness, deafness, or life threatening organ disorders 3,4.
Clinical diagnosis of Rubella is unreliable, as Rubella virus infection can be asymptomatic in up to 50% of infected patients . Thus ,serological tests are needed for a diagnosis, especially when a patient is pregnant6. Rubella antibody testing are so the main diagnostic tool available to either establish a previous exposure to Rubella or Rubella vaccination or a current infection/re-infection with Rubella.
A primary acute Rubella infection is associated with an elevated IgM antibody response to the Rubella virus7; Rubella virus specific IgM are detectable after the incubation period and usually disappear after approximately 8 weeks8. Rubella virus specific IgGs appear immediately after IgMs and they show a greater-than-fourfold rise in their titer8 and persist for life11.
In addition to IgM and IgG determinations immunoglobulin G avidity testing has been shown to be useful for differentiating recent from past Rubella infection12, investigating suspected Rubella in pregnant women13 and congenital Rubella syndrome14.
- DM Horstmann. Rubella in : Evans A.S., ed. Viral infections of humans : epidemiology and control. New York: Plenum Press,1976; 409-427.
- Askin DF. Intrauterine infections. Neonatal.Netw. 2004; 23(5):23-30.
- Cooper LZ,Alford Jr.CA. Rubella. In : Remington JS, Klein JO, editors. Infectious Diseases of the Fetus and Newborn infant. Philadelphia,PA : Elsevier Saunders ; 2006 : 893-926.
- Atreya CD, Mohan KV, Kulkami S. Rubella virus and birth defects : molecular insights into the viral teratogenesis at the cellular level. A. Clin. Mol. Terato. 2004; 70 (7): 431-7.
- Department of Vaccines and Biologicals, WHO. Report of a meeting on preventing congenital Rubella syndrome : immunization strategies, surveillance needs. Geneva : World Health Organization,2000.
- Best JM, Banatvala JE. Rubella. In . AJ Zuckerman, JE Banatvala, JR Pattison,eds. Principles and practice of clinical virology. 4th Chichester : John Wiley,2000: 387-418.
- Best JM, O’Shea S, Tipples G,Davies N, Al-Khusaiby SM, Krause A, Hesketh LM, Jin L, Enders G. Interpretation of Rubella serology in pregnancy-pitfalls and problems. BMJ. 2002;325 (7356): 147-148
- Banatvala JE and Brown DWG. 2004. Rubella. Lancet 363 : 1127-1139
- Banatvala JE,Best JM, O’Shea S,Dudgeon JA. Persistence of Rubella antibodies following vaccination : detection of viremia following experimental challenge. Rev. Infect. Dis 1985; 7(suppl 1): S86-90
- Thomas HIJ, Morgan-Capner P, Roberts A, Hesketh L. Persistent Rubella-specific IgM reactivity in the absence of recent primary Rubella and Rubella reinfection. J. Med. Virol. 1992;36 :188-92.
- O. White and F.J. Fenner. 1994. Medical Virology 4th ed. Academic Press, San Diego,CA.
- Hamkar, S. Jalivand, T. Mokhtari-Azad, K. Nouri Jelyani, H. Dahi-Far,H. Soleimanjahi and R. Nategh.2005. Assessment of IgM enzyme immunoassay and IgG avidity assay for distinguish between primary and secondary immune response to Rubella vaccine. J. Virol. Methods 130 : 59-65.
- Hoffman and U.G. Liebert. 2005. Significance of avidity and immunoblot analysis for Rubella IgM-positive serum samples in pregnant women. J. Virol. Methods 130: 66-71.
- Herne, K. Hedman and P. Reedik. 1997. Immunoglobulin avidity in the serodiagnosis of congenital Rubella syndrome. Eur. J. Clin. Microbiol. Infect. Dis. 16 : 763-766.