Behavior of Bovine Ephemeral Fever Virus in Laboratory Animals and Cell Cultures

Light, immunofluorescent and electron microscopic observations were carried out sequentially on mice and VERO cell cultures infected with bovine ephemeral fever (BEF) virus. In early harvests from cell culture, 185 • 73 nm cone-shaped particles with nearly parallel sides predominated; these particles had all other features typical of the Rhabdoviruses (surface projections, envelope, axial channel, precisely coiled helical nucleocapsid with 35 cross-striations at a 4.8 nm interval). Identical particles were the most frequent form in mouse brain. Variation in shape toward more broadly based cone-shapes occurred late in infection and reflected anomalous morphogenesis or particle breakdown. T (truncated) particles were common at all stages of infection. It was concluded that the reported variation in length and shape of particles in various BEF virus isolates is not necessarily releated to "strain variation" but more likely to varying growth rates and T particle interference associated with varying degrees of adaptation to a host system. BEF viral morphogenesis took place primarily upon plasma membranes in vivo and in cell culture in association with small accumulations of intraeytoplasmic matrix. Fusion of viral envelopes was observed, and an early syncytium formation occurred in infected cell cultures. Cytopathology was similar in vivo and in cell culture; a protracted stage of cell rounding was followed by extreme cytoplasmic vacuolation and condensation and then by lysis. Necrotic encephalomyelitis was severe in moribund mice but extraneural sites of viral propagation and damage were not found with any of the techniques employed. Since this strict neurotropism is most likely not characteristic of naturally acquired BEF virus infection in nature, it was concluded that the mouse was an unsatisfactory host for the further study of pathogenesis.

“…The character of this change was consistent with that reported by others in monkey, bovine, and hamster cells (5,16). Once rounded, cells remained intact for long periods.…”

Section: Bef Virus In Ver 9 Cell Culturesupporting

confidence: 91%

Bovine ephemeral fever virus in cell culture and mice

Murphy

Taylor

Mims

et al. 1972

“…A cell line, ttmLu-i, derived from suckling hamster lung was used (8). The medium for cell growth was Eagle's minimum essential medium (MEM) containing 10 per cent tryptose phosphate broth (Difco), 10 per cent calf serum and antibiotics (100 units/ml penicillin, 100 ~g/ml streptomycin, 1 ~g/ml fungizone).…”

Section: Cell Culturementioning

confidence: 99%

“…The study of the disease had been greatly hampered by the lack of experimental hosts other than the natural host, cattle, until this difficulty was recently overcome by the finding that the causative virus could be propagated in small laboratory animals (1, 4, 5, 10, 11, 1r and, more important, also in cell cultures (4,5,8). A crystal violet vaccine prepared with defibrinated blood from infected cattle was developed in Japan two decades ago (13).…”

Section: Introductionmentioning

confidence: 99%

Formalin-inactivated, aluminum phosphate gel-adsorbed vaccine of bovine ephemeral fever virus

Inaba

Kurogi

Sato

et al. 1973

SummaryAn inactivated vaccine prepared from virus grown in hamster hmg cells produced specific neutralizing antibody by intramuscular inoculation in cattle as well as in mice. Antibody response of cattle after one dose of vaccine was poor both in antibody level and seroconversion rate. However, a second dose given at intervals of 3 or more weeks induced a rapid and high-titered antibody formation in almost all animals. The antibody levels thus attained declined rather rapidly in several months, yet a booster dose given one year later provoked a rapid antibody response. Considering this pattern of antibody response together with the seasonal incidence of the disease it seems adequate that the initial immunization with two doses and the booster inoculation be made in late spring or early summer, immediately before the epizootic season. The vaccination prevented the disease in calves challenged with virulent virus. The vaccine exerted little side effects in cattle. Cows vaccinated during pregnancy gave birth to healthy calves in term. No adverse effects of vaccination on milk prodnetion was shown. All these findings indicate efficacy and safety of the vaccine, although the final evaluation rests on largescale field trials.

Vaccination of cattle against bovine ephemeral fever with live attenuated virus followed by killed virus

Inaba

Kurogi

Takahashi

et al. 1974

SummarySerial passage of bovine ephemeral fever virus in hamster lung cells, HmLu-1, deprived rapidly the virus of virulence for cattle with simultaneous loss of the ability to produce neutralizing antibody. The attenuated virus thus obtained, however, could prime cattle to produce neutralizing antibody rapidly to high titers following a subsequent inoculation of formalin-inactivated, ALP04 geladsorbed vaccine (K). Although one subcutaneous dose of live vaccine (L) prepared from the attenuated virus produces no detectable amonnts of neutralizing antibody unless as heavy a dose as 107 TCIDj0 was used, the priming effect of L vaccine was shown even with 10 TCIDs0. Similar priming effect was also shown in mice by intracerebral inoculation of L vaccine. Maximal antibody response of cattle was obtained by one subcutaneous L vaccine dose of _~ 105TCIDs0 followed by 3 ml of K vaccine administered intramuscularly at intervals of 2 to 4 weeks. This LK method induced seroconversion in nearly all of initially seronegative cattle, and the neutralizing antibody thus produced persisted much longer than that following two doses of K vaccine given at one-month intervals. The LK method exerted little side effects in cattle. Cows vaccinated during pregnancy delivered healthy calves in term. No adverse effect on milk production was shown. The vaccine virus could not be passaged serially in calves by intravenous inoculation of the blood. Lyophilized L vaccine was stored at 4 ~ C with little loss of infectivity for at least one year. Reconstituted vaccine could be used safely at least for 6 hours when kept at 4 ~ C or even at room temperature.All these findings indicate the efficacy and safety of the LK vaccination method, although the final evaluation rests on large-scale field trials.