629: KINETICS OF ANTIBODY RESPONSE IN CRITICALLY ILL PATIENTS WITH MIDDLE EAST RESPIRATORY SYNDROME

Abstract

Learning Objectives: Information on the kinetics of antibody response in critically ill patients with the Middle East respiratory syndrome (MERS) is important for understanding data on diagnosis, seroepidemiology and pathogenesis, and possibly passive immunotherapy. The objective of this study is to examine IgG antibody response in critically ill patients with MERS. Method(s): We enrolled consecutive patients with rRT-PCR-confirmed MERS admitted to the ICU of King Abdulaziz Medical City-Riyadh, Saudi Arabia in 2015-2016. After obtaining informed consent, we collected blood samples prospectively on ICU days 1, 3, 7, 14 and 28. We detected MERS-CoV antibodies by ELISA (Euroimmun AG, Lubeck, Germany), using wells coated with MERS-CoV S1 antigen. Results were reported as the optical density (OD). Result(s): During the study period, we enrolled 40 critically ill patients with a median (Q1, Q3) age of 58 (40, 67) years; 25 (63%) of them have at least one comorbid condition. Patients were admitted to ICU after 9 (4,13) days from onset of symptoms with admission SOFA score of 11 (6.5, 12); 38 (95%) received invasive ventilation, 35 (88%) vasopressors, 21 (53%) renal replacement therapy and 17 (43%) corticosteroids. Among enrolled patients, 19 (48%) died in the hospital. On ICU day 1, median (Q1, Q3) ELISA OD was 0.05 (0.03, 0.66) with 9/39 (23%) were considered reactive. The ELISA OD significantly increased with time (p < 0.001 for change with time): day 3 ELISA OD 0.32 (0.05, 0.96) with 13/29 (45%) considered reactive, day 7 ELISA OD 1.25 (0.85, 1.63) with 6/8 (75%) considered reactive, day 14 ELISA OD 1.35 (0.67, 1.55) with 7/8 (88%) considered reactive and on day 28 ELISA OD 1.73 (1.70, 1.77) with 2/2 (100%) being reactive. ELISA OD was significantly higher among survivors compared to nonsurvivors on day 1 (p = 0.041) and day 3 (p = 0.036). Conclusion(s): Majority of critically ill patients with MERS demonstrate IgG antibody response in the first 4 weeks of illness. This response appears to be associated with survival; which may have important implications for understanding pathogenesis and potential immunotherapy.