Recent knowledge in the enteral coronaviruses in pig. Review article

The article, based on the latest literary data, briefly summarizes the most important aspects of the porcine coronaviruses commonly found in pig herds throughout the world, namely transmissible gastroenteritis virus (TGEV), porcine respiratory coronavirus (PRCV) and porcine epidemic diarrhoea virus (PEDV). It deals with the results of the molecular biological methods applied in corona virology, such as the description of two cellular TGEV receptor proteins, the localization of the putative receptor binding sites on the spike protein of the virion. According to the latest findings published in the literature there are certain characteristic differences in the genome of TGEV and PRCV. The most important one of these, is the deletion localized on the spike gene of the PRCV. This deletion seems to be responsible for the different tissue tropism of the two viruses, and the paper points out the practical importance of this finding. According to the data gathered on passive and active immunization experiments of pigs,the missing sequences code for epitopes crucial in the induction of protective immunity in piglets. The difference of the genomes can be utilized in the diagnostics, to differentiate PRCV and TGEV infections on a serological basis, or by the currently developed nucleic acid analysing techniques. The author mentions the genetic relationships of the three porcine coronaviruses and coronaviruses of other species according to a recent phylogenetic analysis. Based on this analysis there is a marked distance between the closely related TGEV/PRCV and the PEDV. Compares some of the characteristics of the epidemiology and pathogenesis of TGE and FED. In addition it gives some points of reference of the new differential diagnostic methods of the field, such as the use of monoclonal antibodies or the development of polymerase chain reaction assays and the application of non-radioactive probes in in situ hybridisation tests