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The study aimed to identify the changes of anatomic and microscopic structure and the expression and localization of hypoxia-inducible factor (HIF)-1α and vascular endothelial growth factor (VEGF) in the myocardium and coronary artery of the yak heart adapted to chronic hypoxia with aging. Thirty-two yaks (1 day, 6 months, 1 year, 2 years, and 5 year old) were included, and immunoelectronmicroscopy, immunohistochemistry, and enzyme-linked immunosorbent assay (ELISA) were used. Right ventricular hypertrophy was not present in yaks with aging. There was no intima thickening phenomenon in the coronary artery. The ultrastructure of myofibrils, mitochondria, and collagen fibers and the diameter and quantity of collagen changed significantly with aging. The enzymatic activity of complexes I, II, and V increased with age. Immunogold labeling showed the localization of HIF-1α protein in the cytoplasm and nuclei of endothelial cells and cytoplasm of cardiac muscle cells, and VEGF protein in the nuclei and perinuclei areas of smooth muscle cells of coronary artery, and in the cytoplasm and nuclei of endothelial cells. ELISA results showed that HIF-1α secretion significantly increased in the myocardium and coronary artery from an age of 1 day to 2 years of yaks and decreased in old yaks. However, VEGF protein always increased with aging. The findings of this study suggest that 6 months is a key age of yak before which there are some adaptive changes to deal with low-oxygen environment, and there is a maturation of the yak heart from the age of 6 months to 2 years.

Genotype II African swine fever virus (ASFV) has been plaguing Chinese pig industry and caused severe morbidity and mortality of pigs resulting in huge economic losses since its first report in August 2018. Most recently, two genotype I ASFVs with low virulence but efficient transmissibility in pigs were reported in China, which makes the diagnosis and control of this lethal disease more challenging. Therefore, it is prerequisite and important to differentiate genotype I from genotype II upon ASFV outbreaks before making any stringent control procedures. In this study, a duplex real‐time PCR assay based on ASFV E296R gene was established which could simultaneously detect genotypes I and II ASFVs with two pairs of primers and two probes. Plasmid containing ASFV genes was used to test the sensitivity, repeatability, and reproducibility. DNA or cDNA samples of ASFV and other swine viruses were used to test the specificity. The results showed that the established duplex real‐time PCR assay has satisfied specificity, sensitivity, repeatability, and reproducibility. In addition, the assay was applied to differentiate 84 ASFV positive clinical samples including lymph nodes, spleen, kidney, lung, liver, blood, nasal swab, and environmental swab samples which were sent to National ASF Reference Laboratory from April 2020 to September 2021. The results showed that all these ASFV positive samples belong to genotype II ASFV. The established duplex real‐time PCR in this study provides a powerful tool for rapid detection and differentiation between genotypes I and II ASFVs and will facilitate efficient control of ASFV in China.