Methods
A 400-sow breed-to-weaning farm in Dongnai province, Viet Nam, with a history of infecting African Swine Fever in 2019. Reproductive disorder manifestations have been recorded in sows recovering from an ASF outbreak since August 2020. The pigs showed no problem, no fever, or anorexia other than reproductive. In a 36-sow barn, 11 sows were found with abortion and 25 sows did farrowing. Out of the 25 sows, 9 sows farrowed to entirely mummified piglets, 11 sows gave birth to mixed mummification, stillbirth, alive piglets, 5 sows have piglets without mummification. In addition, 100% alive piglets had neurological signs including tremor, ataxia, uncoordinated movements, and died at 3 days post-farrowing. The piglets, examinated at necropsy following strictly to biosafety and animal welfare principles. Tissues including fresh and 10% formalin-fixed lymph nodes, spleen, kidneys, brains were taken for lab testing. The nucleic acid extracted from fresh tissues were used for PCRs. The gel-based PCRs detect PRRSV, porcine parvovirus (PPV), classical swine fever virus (CSFV), and Aujeszky’s disease virus (ADV) following routine used protocols of the diagnostic lab. In addition, a real-time PCR (King, Reid et al. 2003) and gel-based PCR (Agüero, Fernández et al. 2003) recommended by OIE were used to detect ASFV. The formalin-fixed tissue sections were stained with hematoxylin and eosin, following a routine procedure, for microscopic examinations. Also, an immunohistochemistry was performed on the sections following the previously reported procedure (Oura, Powell et al. 1998) with some modifications, using p30 polyclonal antibody (Alpha Diagnostics, Texas, USA).