When direct fluoreslent assay is used to detect the antigens of Porcine Parvovirus (PPV) in tissue samples,the detective rate is very low for the small size of particle of Parvovirus.

• 用免疫荧光直接法检测组织病料中的猪细小病毒（PPV）抗原时，因病毒粒子小，检出率较低。