Prevalence and genetic diversity analysis of human coronaviruses among cross-border children

Liu, Peilin; Shi, Lei; Zhang, Wei; He, Jianan; Liu, Chunxiao; Zhao, Chunzhong; Kong, Siu Kai; Loo, Jacky Fong Chuen; Gu, Dayong; Hu, Longfei

Keywords: Human coronaviruses, Cross-border children, Molecular epidemiology, Phylogenetic analysis, Genetic diversity Background Human coronaviruses (HCoVs) have been causing worldwide outbreak with cases of hospitalization [1] . Six types of coronaviruses (CoVs) are known to infect human: two α-CoVs, i.e. 229E and NL63, two β-CoVs group A, i.e. HKU1 and OC43, β-CoVs group B, i.e. Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) and β-CoVs group C, i.e. Middle East Respiratory Syndrome Coronavirus (MERS-CoV). SARS-CoV and MERS-CoV, which are highly pathogenic to human lives and have caused serious diseases or death, causes about 10 and 36% mortality respectively. OC43, HKU1, NL63 and 229E are the most common four HCoVs in most regions, circulating worldwide with a detection rate ranging from 1.1 -8.5% and with variations in their predominantly circulating seasons and strains [2] [3] [4] [5] . HCoVs ranks the third in the detection rate of all 17 respiratory viruses in south of China (Guangzhou) and poses a heavy burden to the health care of children as it is associated with acute upper or lower respiratory tract infections, and cases of death have been reported [6] . Moreover, high mutation rates caused by the low fidelity of RNA-dependent RNA polymerase (RdRp) led to high diversity of HCoVs [7] . Several studies about the genetic diversity of human coronaviruses on hospitalized patients had been carried out previously. The new OC43 genotype D based on the recombination of B and C was discovered in 2005 [8] . Two additional recombinants: E (CH) and E (FR) were reported as homologous genome recombination in 2015 [9, 10] . The genetic features of NL63 were reported at least three distinct circulating genotypes (A, B and C) and one recombinant (cluster R) in the United States in 2011 [11] . Meanwhile, HKU1 strains were grouped into three clusters (A, B and C) due to natural recombination [12] . These previous reports focused on hospitalized patients, who have low mobility and seldom cross the border, while this study hereby firstly reports the analysis on crossborder children, mainly including "cross-boundary students", who are born and attend school in Hong Kong but reside in Mainland China [13, 14] . A border still exists between Shenzhen in Mainland China and Hong Kong (SZ-HK port) due to the colonial history, resulting in different health care and education systems [13] . Children had a high incidence of coronaviruses infection and "cross-boundary students" connecting closely Hong Kong and Mainland China will help us understand the epidemic characteristics of coronaviruses in the Pearl River Delta region. New occurrence of infectious coronaviruses and the known pan-coronavirus variation among this region are of our study interest because the coronaviruses have the potential to threaten global health system and no vaccine is currently available [15, 16] . Therefore, surveillance upon human coronaviruses among this region was carried in this study.