Comparative study of various cell lines susceptibility to cytopathic and non-cytopathic strains of Bovine viral diarrhea virus 1 and 2

Abstract

Keywords: Bovine viral diarrhea virus 1 and 2; cell line susceptibility; virus recovery or by mutants of cp BVDV derived from non-cp BVDV in persistently infected animals. Although many rapid and less laborious diagnostic techniques are used to detect BVDV, up till now the virus isolation is considered as a gold standard. Besides other factors, the success rate of virus isolation depends on the susceptibility of cell line used to detect and isolate the virus.Thus, the aim of this study was to compare the susceptibility of different cell lines derived from various tissues to non-cp and cp strains of BVDV. In our experiments we examined four cell lines derived from various bovine tissues and one cell line derived from sheep fetal thymus cells for the inoculation with BVDV strains. Bovine embryonic lungs (BEL), bovine turbinated (BT), Madin-Darby bovine kidney (MDBK), calf oesopharyngeal (KOP-R), and sheep fetal thymus (SFT-R) cell lines were obtained from the Veterinary Faculty, Munich, Germany. All cell cultures were BVDV-free. Cell cultures were grown in Eagle's MEM (Gibco) supplemented with 7% fetal calf serum (Biochrom), penicillin 100 IU/ml, streptomycin 100 µg/ml (Gibco), and 1% non-essential amino acids (Biochrom). The cells were maintained at 37°C in a humidified 5% CO 2 atmosphere.Cell lines were inoculated with two cp BVDV strains (NADL and Oregon C24V) and two non-cp BVDV strains (PT810 and CS8644) obtained from the Veterinary Faculty, Munich, Germany. Three viral strains tested (NADL, Oregon C24V, PT810) were BVDV-1, whereas fourth strain (CS844) was BVDV-2. Each cell culture was inoculated with 50 µl of viral suspension (10 4.0 TCID 50 /ml per 25 cm 2 of confluent * Corresponding author. E-mail: pistl@uvm.sk; fax: +421-552981011. Abbreviations: BEL = bovine embryonic lungs; BVDV-1 and 2 = Bovine viral diarrhea virus 1 and 2; BT = bovine turbinated; cp = cytopathic; KOP-R = calf oesopharyngeal; MDBK = Madin-Darby bovine kidney; ML = mink lungs; non-cp = non-cytopathic; SFT-R = sheep foetal thymus Bovine viral diarrhea virus 1 and 2 (BVDV 1 and 2) (the genus Pestivirus, the family Flaviviridae) is distributed worldwide and causes severe economical losses due to the decreased fertility, abortions, diarrhea, respiratory symptoms, and persistent infection in intrauterinary infected calves. So far, two species BVDV-1 and BVDV-2 are known to infect cattle (1). Most of the BVDV isolates appear to be BVDV-1 genotype that comprises 12 different genetic groups (2). Strains of BVDV-2 genotype were initially recognized by their higher virulence, but the isolates of lower virulence have also been assigned to this genotype (3). According to the cultivation characteristics and pathogenic properties of BVDV-1, 2 we differentiate between cytopathic (cp) and non-cytopathic (non-cp) BVDV strains (4). Non-cp BVDV strains are capable of producing persistent infection and consequently, this is the reason why most of the field isolates are of the non-cp type. Persistently infected animals are life-long virus shedders and are...