MERS-CoV in Dromedary Camels: Sequence-Based Comparison of Antigenicity and Pathogenicity of Structural and Non-Structural Proteins

Abstract

The goal of this researcher was to map the camel MERS-CoV structural and non-structural proteins and track changes in antigenicity and pathogenicity from 2013 to 2018. This is critical for developing effective diagnostic and control methods. Therefore, the sequences of MERS-CoV structural proteins such as Spike (S), Membrane (M), Nucleocapsid (N) and Envelope (E) and nonstructural proteins, comprising polyprotein-ab (polyab) and Open reading frame-3 (ORF3) were retrieved. The amino acid sequences of each of these proteins were analysed to estimate their antigenic and pathogenic properties from 2013 to 2018. The antigenicity profiles showed variations in antigenicity minimum, maximum, range, and average from 2013 to 2018. MERS-CoV proteins’ maximum antigenicity score was declining in the examined time frame. In 2013, the maximum score was 0.86, and by 2018, it had dropped to 0.6. This resulted in a greater range of antigenicity with the onset of MERS-CoV in 2013, with a range of 0.56, which eventually decreased to 0.22 in 2018. The net effect on the mean value of antigenicity score revealed that MERS-CoV antigenicity decreased gradually. Between 2013 and 2018, the mean antigenicity score of structural and nonstructural proteins decreased. Non-structural proteins, on the other hand, had the greatest alterations, with a mean value of 0.52 in 2013 and 0.42 in 2018, representing a loss of 19.2 per cent of their antigenicity score. In contrast, the structural protein showed a mean value of 0.55 in 2013 and 0.53 in 2018, i.e. lost only 3.6% of its antigenicity score. Given that ORF3 was nonantigenic, therefore, all changes in antigenicity changes were attributed to polyab protein. Pathogenicity score has decreased from 0.81 in 2013 to 0.78 in 2018. Further studies are required to map these changes on the virus-host cell interaction level.