Animal coronaviruses - detection and characterization

In Denmark, we monitor both domestic and wild animals for serious infectious diseases through the veterinary contingency. Coronaviruses are important pathogens in both animals and humans. Some of these viruses are hosted by pigs where they are capable of causing serious illness. Wild populations of bats are reservoirs of coronavirus, and in other parts of the world it has previously been seen that coronavirus from bats has spread to other animal species including pigs and humans.

In this PhD study, selected coronaviruses in animals have been studied in more detail with regard to the detection of the presence of viruses in samples and the characterization of these viruses on several parameters: occurrence, phylogeny / nucleotide sequences, antigenic properties and virulence.

Bats in Denmark have been tested for the presence of coronavirus, and we have found an average of 21% of the samples and 5 out of 10 studied species of bats positive for various coronaviruses. In phylogenetic studies, we have found that some of these new coronaviruses are related to previously found coronaviruses in the corresponding species of bats in other European countries. Perhaps the newly found viruses even constitute new species, however, all within the genus Alphacoronavirus and thus they are related to several coronaviruses from pigs, such as the porcine epidemic diarrhea virus.

Porcine epidemic diarrhea virus (PEDV) has never been detected in Denmark. An introduction of PEDV to Denmark could potentially lead to deteriorating animal welfare and substantial economic impact for pig producers due to the loss of pigs and export restrictions. Therefore, it is important that our diagnostic tools are updated to the variants of viruses that exist, that we know the clinical disease picture and that we gain more basic virological knowledge about PEDV. In this study, we validated real-time RT-PCR tests for use in the veterinary contingency that can detect and distinguish between PEDV and a recombinant coronavirus containing a gene from PEDV. We have also examined existing serological assays to determine which viral proteins are recognized and have found that both the spike protein and the nucleocapsid protein are recognized in the test to varying degrees under different conditions. In addition, we performed an animal experiment in which newer PEDV variants from Germany and Italy were given to eight pigs. They became infected but showed only mild signs of illness. A more serious course can possibly be seen when the infection occurs in a pig herd with many susceptible individuals of different ages and where other contributing factors are present.