Healthy volunteers
A total of 410 healthy children (227 males, 183 females) aged 0–18
years were recruited. All were healthy volunteers from Chongqing, China.
We defined “healthy” as follows: normal nutritional status, no
evidence of infectious disease, no medication, no contact with persons
with infectious disease, no immunizations for at least the last 4 weeks,
no blood transfusions, no history of atopic disorders, and no evidence
of hematological or immunological disorders. All participants underwent
regular blood tests, liver and renal function tests, serological tests
for hepatitis B virus, and real-time PCR for EBV and cytomegalovirus.
Blood samples were obtained from September 2014 to June 2015. DNA was
extracted from peripheral blood.