Borna disease virus (BDV) predominantly infects horses and sheep, causing a broad range of behavioural disorders. It is controversial whether BDV infects humans and causes psychiatric disorders.

We searched for BDV-derived nucleic acids in blood of race horses and jockeys riding the horses.

We assayed for the BDV genome in RNA extracted from peripheral blood mononuclear cells (PBMC) of 39 race horses and 48 jockeys. Two polymerase chain reaction protocols [one-tube reverse transcription–polymerase chain reaction (RT-PCR) and two-step RT-PCR] were used to assay BDV p24 and p40 transcripts.

The p24 and p40 viral nucleic acid sequences were not detected in the PBMC RNAs from any of the race horses or jockeys.

These data do not support an epidemiological association between BDV infection, race horses and humans.

Vitamin D insufficiency is known to be related to cardiometabolic disorders; however, the associations among serum 25-hydroxyvitamin D (25(OH)D) concentration and metabolic syndrome and cardiometabolic risk factors in children and adolescents have not yet been clearly delineated. For this reason, we investigated the relationship among serum 25(OH)D concentration and metabolic syndrome and cardiometabolic risk factors among Korean adolescents.

We performed a cross-sectional analysis and used hierarchical multivariate logistic regression analysis models to adjust for confounding variables.

We used the data gathered during the 2008–2009 Korea National Health and Nutrition Examination Survey (KNHANES).

Our subjects included 1504 Korean adolescents aged 12–18 years who participated in the KNHANES.

Vitamin D insufficiency, defined as 25(OH)D concentration <50 nmol/l, was found in 75·3 % of Korean adolescents and was associated with an increased risk of the prevalence of metabolic syndrome. Waist circumference and BMI were the most closely correlated cardiometabolic components of metabolic syndrome according to serum 25(OH)D status, but no significant relationship was found between serum 25(OH)D concentration and insulin resistance or for the risks for high blood pressure, hyperglycaemia, reduced HDL-cholesterol or hypertriacylglycerolaemia, with or without adjustment for confounding variables.

Low serum 25(OH)D concentration appears to be associated with several cardiometabolic risk factors and an increased risk of the prevalence of metabolic syndrome in Korean adolescents.