Establishment of technology for the simultaneous detection of nucleic acids of African and classic swine fever viruses

Wei-Cheng Hsu

Abstract

African swine fever (ASF) and classical swine fever (CSF) are two highly significant diseases affecting the global swine industry. Due to the prevalence of these diseases in the Asian region and their similarities in transmission speed, clinical symptoms, and macroscopic lesions, there is a need for rapid and accurate diagnostic methods to distinguish between the two diseases. Faced to the escalating threat of African swine fever invasion, there is a continuous need for Taiwan to take proactive measures. In addition, it was in the critical period of eradicating classical swine fever, as there is a possibility of its resurgence. This study compared three sets of primers and probes which have been published in international journals to identify suitable tools for detecting these two diseases. Sensitivity and specificity tests were conducted using domestically detected positive samples for classical swine fever and African swine fever (including animal experiment specimens and meat products), as well as negative nucleic acid samples. Comparative analysis with the standard methods announced by the Ministry of Agriculture indicated that the simultaneous detection technology achieved a sensitivity and specificity of 100% for African swine fever and 95.8% and 100% for classical swine fever. This study provides a rapid, accurate, and convenient method for simultaneously detecting antigens of classical swine fever and African swine fever.

Detection of Tembusu Virus in Poultry in Taiwan

Yen-Ping Chen

Abstract

Tembusu virus (TMUV) is an emerging arbovirus, belongs to the genus Flavivirus within the family Flaviviridae and was first identified from Culex mosquitoes in Malaysia in 1955. TMUV was then occasionally reported in different surveys in Southeast Asia during the 1970s. Since 2010, several outbreaks caused by TMUV have been reported in duck farms in China, with severe egg drop syndrome. This series of outbreaks eventually spread to duck farms in Malaysia and Thailand. In addition to causing significant decreases in duck egg production, TMUV infection in ducks can also result in decreased appetite, depression, retarded growth, diarrhea and neurological dysfunction. Upon infection, morbidity rates are typically 90% to 100% and mortality rates range from 5 to 15% and occasionally increasing to 30% due to secondary bacterial infections. In previous studies, TMUV has also been noticed to cause similar clinical symptoms in TMUV-infected chickens and geese, and has also been isolated from mosquitoes, pigeons and sparrows. In Taiwan, TMUV was first identified in Culex mosquitoes and duck farms in 2019, and was also detected in goose farms afterward. In this report, we describe cases of TMUV infection in poultry farms in Taiwan; analyze the nucleic acid sequences of the isolated TMUV; and establish RT-PCR and real-time RT-PCR for detecting nucleic acids of TMUV in Taiwan, which detection limits are 1,000 and 10 copies, respectively.