From 2003 onwards, three pandemics have been caused by coronaviruses: severe acute respiratory syndrome coronavirus (SARS-CoV); middle east respiratory syndrome coronavirus (MERS-CoV); and, most recently, SARS-CoV-2. Notably, all three were transmitted from animals to humans. This would suggest that animals are potential sources of epidemics for humans. The emerging porcine delta-coronavirus was reported to infect children. This is a red flag that marks the ability of PDCoV to break barriers of cross-species transmission to humans. Therefore, we conducted molecular genetic analysis of global clade PDCoV to characterize spatio-temporal patterns of viral diffusion and genetic diversity. PDCoV was classified into three major lineages, according to distribution and phylogenetic analysis of PDCoV. It can be determined that PDCoV originated in Asia—most likely in Southeast Asia—through inference of migration rate and transmission routes. We also selected six special spike amino acid sequences to align and analyze to find seven significant mutation sites. The accumulation of these mutations may enhance dynamic movements, accelerating spike protein membrane fusion events and transmission. Altogether, our study offers a novel insight into the diversification, evolution, and interspecies transmission and origin of PDCoV and emphasizes the need to study the zoonotic potential of the PDCoV and comprehensive surveillance and enhanced biosecurity precautions for PDCoV.

Seneca Valley virus (SVV) strain (SVA/GD/China/2018) was first isolated from a buffalo farm in Guangdong, China, using seven mammalian cell lines. A genetic analysis revealed that SVA/GD/China/2018 had a high nucleotide similarity with the porcine-origin SVV strains, revealing potential cross-species transmission of SVV from pigs to buffaloes.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), along with Severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East Respiratory Syndrome Coronavirus (MERS-CoV) are three emerging coronaviruses with huge public health in the 21st century. Especially, SARS-CoV-2 causes an unprecedented global pandemic and has spread in over than 200 countries. Clinically, SARS-CoV-2 could co-infected with respiratory pathogens including influenza virus and adenovirus in some present cases. This suggests that the differential diagnosis cannot be ignored. To investigate whether SARS-CoV-2 exists earlier and identify possible co-infection in human with respiratory disease, we performed the detections of SARS-CoV-2 and influenza virus using real-time RT-PCR method and colloidal gold test strip in 534 throat swab samples collected in influenza epidemic season (from January to May of 2019). 336 samples (62.9%) were tested positive for influenza virus, which involved into 230 single influenza A virus (IAV)-positive samples, 4 single influenza B virus (IBV)-positive samples, and 102 IAV and IBV co-infection samples. Unfortunately, we found no positive signal of SARS-CoV-2 in 534 samples. Our finding reveals absence of SARS-CoV-2 infection in human archived samples in before the outbreak of SARS-CoV-2 in China. In addition, this study suggests that IAV was still major respiratory pathogen responsible for respiratory disease in the influenza season.