ABSTRACT
The interferon-γ testing and the comparative cervical skin test were compared with the simple cervical hypersensitivity test routinely used in our country in herds infected with Mycobacterium bovis, in which 167 infected cattle from 5 herds were tested with interferon-γ testing and the comparative cervical test (CCT) simultaneously and other 106 cattle were tested with other hypersensitivity tests used as control for comparison. In these 167 cattle tested with both tests, 89 cattle were proved to be positive both in interferon-γ testing and CCT using the bovine PPD of Netherland with a coincidence rate of 92.7% (89/96). In 106 cattle the coincidence rate of positive reactions detected by γ-interferon test and CCT was 93.41% (78/83.5), that detected by the routine skin of foreign country was 62.26%(66/106); and that between the hypersensitivity test of China and foreign country was 92.19% (59/64). It is obvious that the interferon-γ testing and CCT seem to have higher coincidence rate and the specificity of the skin tests used in our country was rather low. Consequently, the use of the comparative cervical skin test should be considered to replace the routinely used shin tests.
ABSTRACT
One influenza H3N2 virus, A/swine/Shandong/3/2005 (Sw/SD/3/2005), was isolated from pigs with respiratory disease on a farm in eastern China. Genetic analysis revealed that Sw/SD/3/2005 was a triple-reassortant virus with a PB2 gene from human-like HIN1, NS from classical swine H1NI, and the remaining genes from human-like H3N2 virus. These findings further support the concept that swine can serve as reservoir or mixing vessels of influenza virus strains and maintain genetic and antigenic stability of viruses. Furthermore, we have successfully established a reverse genetics system based on eight plasmids and rescued Sw/SD/3/2005 through cell transfection. HI tests and RT-PCR confirmed that the rescued virus maintained the biological properties of the wild type Sw/SD/3/2005. The successful establishment of the reverse genetics system of Sw/SD/3/2005 will enable us to conduct extensive studies of the molecular evolution of H3N2 influenza viruses in swine.