Longevity of seropositivity and neutralizing antibodies in recovered MERS patients: a five-year follow-up study

Cheon, Shinhye; Park, Uni; Park, Hyoree; Kim, Yuri; Hai Nguyen, Yen Thi; Aigerim, Abdimadiyeva; Rhee, Ji-Young; Choi, Jae-Phil; Park, Wan Beom; Park, Sang Won; Kim, Yeonjae; Lim, Dong-Gyun; Yang, Jeong-Sun; Lee, Joo-Yeon; Kim, Yeon-Sook; Cho, Nam-Hyuk

OBJECTIVES: We aimed to assess the longevity of spike-specific antibody responses and neutralizing activity in the plasma of recovered Middle East respiratory syndrome (MERS) patients. METHODS: We traced the antibody responses and neutralizing activity against MERS coronavirus (MERS-CoV) in peripheral blood samples collected from 70 recovered MERS patients for five years after the 2015 MERS outbreak in South Korea. We also measured the half-life of neutralizing antibody titers in the longitudinal specimens. RESULTS: The seropositivity rate persisted for up to four years (50.7–56.1%), especially in MERS patients who suffered from severe pneumonia, and then decreased (35.9%) in the fifth year. Although the spike-specific antibody responses decreased gradually, the neutralizing antibody titers decreased more rapidly (half-life: 20 months) in 19 participants without showing negative seroconversion during the study period. Only five (26.3%) participants had neutralizing antibody titers greater than 1/1,000 of PRNT(50), and a high neutralizing antibody titer over 1/5,000 was not detected in the participants at five years after infection. CONCLUSIONS: The seropositivity rate of the recovered MERS patients persisted up to four years after infection and significantly dropped in the fifth year, whereas the neutralizing antibody titers against MERS-CoV decreased more rapidly and were significantly reduced at four years after infection.