A systematic review of MERS-CoV (Middle East Respiratory Syndrome Coronavirus) seroprevalence and viral RNA prevalence in dromedary camels: implications for animal vaccination

Abstract

27Human infection with Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is driven by 28 recurring dromedary-to-human spill-over events, leading decision-makers to consider dromedary 29 vaccination. Dromedary vaccine candidates in the development pipeline are showing hopeful results, 30 but gaps in our understanding of the epidemiology of MERS-CoV in dromedaries must be addressed 31 to design and evaluate potential vaccination strategies. We systematically reviewed the published 32 literature reporting seroprevalence and/or prevalence of active MERS-CoV infection in dromedary 33 populations from both cross-sectional and longitudinal studies, including 60 studies in our qualitative 34 syntheses. MERS-CoV seroprevalence increased with age up to 80-100% in adult dromedaries 35 supporting geographically wide spread endemicity of MERS-CoV in dromedaries in both the Arabian 36 Peninsula and countries exporting dromedaries from Africa. The high prevalence of active infection 37 measured in juveniles and at sites where dromedary populations mix should guide further 38 investigation -particularly of dromedary movement -and inform vaccination strategy design. 39 40 41 42 43 44 45 46 47 48 49 50 . CC-BY 4.0 International license author/funder. It is made available under a The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/574103 doi: bioRxiv preprint 65 studies (7). 66 However, vaccine strategy evaluation is currently precluded by gaps in the understanding of the 67 epidemiology of MERS-CoV in dromedaries. The dromedary population is highly heterogeneous and 68 spans a wide geographic area stretching from West Africa through to the Middle East and parts of 69 Asia. Knowing when and where dromedaries would need to be targeted, and the likely impact of 70 vaccination, is necessary before further consideration of dromedary vaccination in the wider 71 socioeconomic and cultural context. 72 Here, we systematically reviewed published studies that measured MERS-CoV antibody 73 seroprevalence in dromedaries and/or prevalence of viral RNA in dromedaries. Assuming assay 74 specificity and long-term presence of antibodies after infection, seroprevalence can be used to 75 estimate what proportion of a dromedary population has ever been infected with MERS-CoV. Broken 76 down by age class, this can tell us when most animals encounter the infection for the first time. 77 Additionally, although whole-virus isolation and culture is necessary to confirm whether the shedding . CC-BY 4.0 International license author/funder. It is made available under a The copyright holder for this preprint (which was not peer-reviewed) is the . https://doi.org/10.1101/574103 doi: bioRxiv preprint 101 When available, we took the results of neutralisation-based testing over methods that determined 102 seropositivity based on antibody screening tests alone. Neutralising antibody tests are more specific 103 and are the WHO (World Health Organisation) recommended method for confirming MERS-CoV 104 seropositi...

Serological exposure in Bactrian and dromedary camels in Kazakhstan to a MERS or MERS‐like coronavirus

“…Younger camels in Kazakhstan had a higher probability of seropositivity, indicating that there was not endemic circulation of MERS‐CoV during the sampling period as in endemic regions, older camels have higher levels of seropositivity. There was no difference in the probability of seropositivity between males and females, similar to the majority of studies (Dighe et al., 2019). However, studies in Kenya did find significant differences where females had higher rates of seroprevalence (Munyua et al., 2017), while male camels in Egypt and KSA had higher seroprevalence compared with female camels (M. A. Ali et al., 2017; Kasem et al., 2018).…”

“…We found that seroprevalence in Kazakhstan (0.35%) was substantially lower compared with any other region (Dighe et al., 2019). The lowest prior detected seroprevalence was in the Canary Islands (4% from 170 camels sampled) and in Mongolia (9.4% from 180 camels) (Bold et al., 2020; Gutiérrez et al., 2015).…”

“…Since the initial detection, MERS‐CoV has been found in camels in at least 27 countries (World Health Organization, 2020). There is serological evidence of MERS‐CoV infection in dromedaries throughout the Arabian Peninsula and in Bangladesh, Egypt, Ethiopia, Kenya, Nigeria, Somalia and Sudan, with seroprevalence ranging from 30 to 100% (Bold et al., 2020; Dighe et al., 2019; Islam et al., 2018). Bactrian and dromedary camels in Mongolia previously tested negative for MERS‐CoV infection; however, a recent study from Mongolia detected MERS‐CoV antibodies in Bactrian camels (Bold et al., 2020; Chan et al., 2015).…”