Oral Presentation 20th Lancefield International Symposium on Streptococci and Streptococcal Diseases 2017

Validation of a rapid diagnostic assay based on antibodies to human cardiac myosin S2 epitopes to monitor rheumatic heart disease (#60)

Mohan Karmarkar 1 , Nuzhat Surve 1 , Preeti Mehta 1 , Chandrahas Deshmukh 1 , Charan Lanjewar 1 , Prafulla Kerkar 1 , Robert Norton 2 , Natkunam Ketheesan 3 , Kadaba Sriprakash 4
  1. Seth G S Medical college and KEM Hospital, Mumbai, MAHARASHTRA, India
  2. Townsville Hospital, Townsville, Queensland, Australia
  3. James Cook University, Townsville, Queensland, Australia
  4. QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia

Introduction: Ongoing cardiac damage can be identified by the presence of high levels of autoantibodies to human cardiac myosin (HCM) in acute rheumatic fever and rheumatic heart disease (ARF/RHD). We hypothesize that these antibodies and in particular antibodies to immuno-dominant epitopes of the S2 region of HCM can be used for both sero-diagnosis of ARF/RHD and monitoring of the disease progression. Since India is a major contributor to global burden of ARF/RHD and is associated with different circulating M types of Group A streptococci and HLA types of patients, it is important that we validate the HCM immuno-dominant epitopes as has been determined in some other populations.

Methods: In our pilot study, ELISA was performed with serial samples of sera from patients with ARF/RHD and controls. Using 32, 25mer overlapping peptides from the S2 region of HCM (Mimitopes, Australia), we determined antibody titers.

Results: Our pilot study demonstrates that the mean reactivity of patient group is higher for epitopes S2-21 & S2-22 in contrast to the other studies which suggest S2-1, 2 & 8 as immuno-dominant epitopes.

Discussion: ELISA performed on our patient serum samples (EC/GOVT-07/2012) from India is useful in identifying the immuno-dominant S2 epitopes. This could lead to the identification of a universal serological marker for the diagnosis and assessment of ongoing cardiac damage in patients with ARF/RHD. Our findings from the Indian cohort will be presented and it would add to the discussion for the need for an economically viable, rapid, point-of-care test for ARF/RHD.