Molecular characterization and phylogenetic analysis of VP1 of porcine enteric picornaviruses isolates in Italy.

Porcine enterovirus (PEV), Porcine Teschovirus and Porcine sapelovirus, belonging to the family Picornaviridae, are ubiquitous and mainly cause asymptomatic infections in pigs. In this study, a total of 40 Italian porcine picornavirus isolates were characterized by sequencing the capsid VP1-encoding gene. This procedure turned out to be a useful diagnostic tool for the molecular identification of porcine enterovirus, teschovirus and sapelovirus strains and for the study of molecular epidemiology and evolution of these viruses confirming the possibility of correlating virus genotype to serotype.

Foot-and-mouth disease virus: a first inter-laboratory comparison trial to evaluate virus isolation and RT-PCR detection methods.

Five European reference laboratories participated in an exercise to evaluate the sensitivity and specificity of their routinely employed RT-PCR tests and cell cultures for the detection and isolation of foot-and-mouth disease (FMD) virus. Five identical sets of 20 coded samples were prepared from 10 vesicular epithelia, which were derived from submissions from suspect cases of FMD or swine vesicular disease (SVD). Sixteen samples were derived from six FMD virus positive epithelia representing four different serotypes (two each of types O and A and one each of types Asia 1 and SAT 2), two from samples which had been found to be negative by antigen ELISA and virus isolation (VI) in cell culture and two from SVD virus positive epithelia. Some of the FMD virus positive samples were prepared from 10-fold serial dilutions of three of the initial suspensions. Each laboratory tested the samples by one or more of its available RT-PCR procedures and inoculated cell cultures that it routinely uses for FMD diagnosis in attempts to isolate virus, the specificity of which was confirmed by antigen ELISA. The best of the RT-PCR assays used in each laboratory gave comparable results while the sensitivity of cell cultures was variable from high in one laboratory, moderate in two and low in two others. This prototype panel of samples would appear suitable for external quality assurance of these tests but would benefit from the inclusion of more negative samples and an extension in the serial dilution range of one or more of the FMD positive sample titration series.

Cultivation of foot-and-mouth disease virus in BHK21 cells grown in microcarrier culture system.

When BHK21 cells were grown according to the microcarrier's system, they reached the highest concentration in 72 hrs. The infectivity of Foot-and-Mouth Disease (FMD) virus in BHK21 microcarrier culture increased 10 times compared with the conventional monolayer culture in rolling bottles.

Induction and characterization of swine beta interferon.

Newcastle Disease Virus (NDV) strain "H" and Polyinosinic-Polycytidylic acid (Poly I:C) were used for interferon (IFN) induction in secondary pig kidney cells. A functional IFN system was detected and characterized. A wide similarity with the correspondent human and bovine systems was appreciated, with particular regard to the kinetics of synthesis. A glycosylated protein was essential for activity in bovine cells, but not in swine cells. Poly I:C proved to be a very weak inducer, even in conditions which promote IFN synthesis in other cell substrata. beta IFN from secondary pig kidney cells was very effective against Swine Vesicular Disease Virus (SVDV), whereas no activity was detected against porcine Rotavirus; Aujeszky's disease virus, BUK strain, proved to be of intermediate sensitivity. The results of these latter experiments are discussed, with regard to the cells used and to the IFN sensitivity of the tested viruses.