Opposite effects of two different strains of equine herpesvirus 1 infection on cytoskeleton composition in equine dermal ED and African green monkey kidney Vero cell lines: application of scanning cytometry and confocal-microscopy-based image analysis in a quantitative study.

Viruses can reorganize the cytoskeleton and restructure the host cell transport machinery. During infection viruses use different cellular cues and signals to enlist the cytoskeleton for their mission. However, each virus specifically affects the cytoskeleton structure. Thus, the aim of our study was to investigate the cytoskeletal changes in homologous equine dermal (ED) and heterologous Vero cell lines infected with either equine herpesvirus 1 (EHV-1) strain Rac-H or Jan-E. We found that Rac-H strain disrupted actin fibers and reduced F-actin level in ED cells, whereas the virus did not influence Vero cell cytoskeleton. Conversely, the Jan-E strain induced polymerization of both F-actin and MT in Vero cells, but not in ED cells. Confocal-microscopy analysis revealed that alpha-tubulin colocalized with viral antigen in ED cells infected with either Rac-H or Jan-E viruses. Alterations in F-actin and alpha-tubulin were evaluated by confocal microscopy, Microimage analysis and scanning cytometry. This unique combination allowed precise interpretation of confocal-based images showing the cellular events induced by EHV-1. We conclude that examination of viral-induced pathogenic effects in species specific cell lines is more symptomatic than in heterologous cell lines.

Equine herpesvirus type 1 quantification in different types of samples by a real-time PCR.

Equine herpesvirus type 1 (EHV-1) is one of the major viral agents causing diseases in horses common worldwide. A variety of techniques, including PCR, have been used to diagnose EHV-1 infections. In this paper, an attempt of real-time PCR has been described, which uses specific fluorochrome-labeled TaqMan probes for detection of viral DNA. This method does not require post-amplification manipulations, thereby reducing the risk of cross-contamination. The assay was sensitive enough to detect EHV-1 sequences in different clinical samples, as well in mice neuronal cell cultures. The technique was also very specific--here was no cross reaction with other human and equine herpesviruses. Compared to previously used nested PCR technique, the test was more sensitive and should be useful for the common diagnosis based on its specificity and rapidity.

Replication of equine herpesvirus type 1 in equine dermal cells transfected with Bam HI[G] restriction fragment of EHV-2 genome.

In previous experiments, we have demonstrated that the presence of equine herpesvirus 2 (EHV-2) enhanced plaque formation in cell cultures infected with equine herpesvirus type 1. To determine whether a specific region of the EHV-2 genome is responsible for this effect, we have constructed a library of Bam HI fragments of the EHV-2 genome ligated into pcDNA plasmid. Equine dermal (ED) cell cultures were subsequently transfected with the constructs, passaged 5 times, tested for the presence of the plasmids and infected with EHV-1 at MOI = 0.01. Only in cultures transfected with the pcDNA/Bam HI[G]construct, designated delta2/4, the mean number of plaques at 24 hrs p.i. was approximately 10 times higher than in non-transfected controls. Virus titers in culture supernatants as well as in freeze-thawed cells were 4- and 5-fold higher, respectively, than in non-transfected cultures. These differences were observed only at 24 hrs p.i. At 48 hrs p.i. cultures were completely destroyed and, surprisingly, the virus titer was slightly lower in the supernatant of transfected cells. However, the titer of EHV-1 in freeze-thawed culture was exactly the same as in the control. These results suggest that the presence of Bam HI[G] fragment of the EHV-2 genome stimulates (accelerates?) plaque formation only at earlier stages of infection but does not influence the total yield of EHV-1 at 48 hrs p.i. The exact mechanism of this stimulation remains unclear and further experiments are necessary to determine the role of putative EHV-2 proteins encoded by Bam HI [G] fragment of the EHV-genome.