Ibaraki Virus, an Agent of Epizootic Disease of Cattle Resembling Bluetongue

Abstract

Outbreaks of an acute febrile disease of cattle occurred in Japan in 1959 and 1960. Its occurrence was limited in late summer and autumn, and in Kyushu, Shikoku and Honshu roughly south of 37 degrees north latitude, suggesting a close correlation of the incidence with the climatic conditions, hence a possibility of the presence of arthropod vector. The disease was characterized by fever and lesions affecting the mucous membrane and skin, musculature and vascular system. Degeneration of striated muscles was observed in the esophagus, larynx, pharynx, tongue and skeletal muscular system. Edema and hemorrhage were marked in the mouth, lips, abomasum, coronets etc., occasionally followed by degeneration of the epithelium leaving erosions or ulcerations. Severe lesions affecting the esophageal and laryngopharyngeal musculature caused deglutitive difficulty which in turn resulted in dehydration and emaciation, and occasionally in aspiration pneumonia, constituting the major causes of death of the affected animals. These findings indicate that the disease resembles bluetongue in sheep and cattle. The clinical materials obtained from natural cases induced a clinical illness when inoculated into calves, and the disease was transmitted serially in calves by intravenous inoculation of the blood obtained at the height of febrile reaction. The experimentally produced disease was clinically and pathologically indistinguishable from the natural disease.

Ibaraki Virus, an Agent of Epizootic Disease of Cattle Resembling Bluetongue

“…The technique of the test was essentially that described earlier [16]. In this study the virus dilution method was used.…”

“…This strain was maintained by serial passage in BK cell culture, after 10 passages in primary cultures of bovine embryonic kidney (BEK) cells. The strain was originally isolated from the blood of a natural case in 1959 [16]. Virus at the 5th BK passage level was used in most experiments.…”

“…Primary cultures of calf kidney (BK) cells were prepared as previously described [16]. Trypsin-dispersed cells were grown in LE medium (Earle's solution containing 0.5% lactalburnin hydrolysate) supplemented with 10% bovine serum for 4 or 5 days at 37C.…”

“…Antigens were prepared from brain tissues of suckling mice infected within 1 or 2 days of age with strain Ibaraki-2 or bluetongue virus type 10 passaged several times intracerebrally in suckling mice [12]. The method of preparation was described elsewhere [16]. Antigens prepared from brains of normal suckling mice of the same age served as the negative controls.…”

“…Ibaraki virus was isolated from natural and experimentally produced cases of an epizootic disease of cattle which was recognized in Japan in 1959 and 1960, and has been proven to be the etiologic agent of the disease [16]. It was noticed that the disease was reminiscent of bluetongue in its seasonal incidence, symptomatology, and pathology [15].…”