Pathology of fatal highly pathogenic H5N1 avian influenza virus infection in large-billed crows (Corvus macrorhynchos) during the 2004 outbreak in Japan.

Highly pathogenic H5N1 avian influenza viruses were isolated in 9 large-billed crows that died in Kyoto and Osaka prefectures in Japan from March to April in 2004. We studied 3 of the 9 crows using standard histologic methods, immunohistochemistry, and virus isolation. The most prominent lesions were gross patchy areas of reddish discoloration in the pancreas. The consistent histologic lesions included severe multifocal necrotizing pancreatitis, focal degeneration and necrosis of neuron and glial cells in the central nervous system, and focal degeneration of cardiac myocytes. All of these tissues contained immunohistochemically positive influenza viral antigens. The virus was isolated from the brain, lung, heart, liver, spleen, and kidney of the crows examined. Thus we concluded that highly pathogenic avian influenza virus was associated with clinical disease, severe pathologic changes, and death in the 3 crows.

Studies of foetuses from cows clinically affected with bovine leucosis.

Five foetuses at varying stages of gestation were recovered from cows showing clinical signs of infection with bovine leukaemia virus (BLV). No pathological changes were found in the foetuses although BLV was isolated from 2 of these foetuses. No antibody to BLV could be detected by virus-neutralisation or immunodiffusion (ID) techniques in these two foetuses, although neutralising antibody alone was detected in one of the other 3 foetuses which were all negative for virus.

Syncytium-induction inhibition test with complement for detection of antibodies against bovine leukemia virus.

A modified syncytium-induction inhibition test which is more sensitive than the immunodiffusion test, was developed using rabbit complement. In this test, fetal lamb kidney cells continuously infected with bovine leukemia virus were used as effector cells, and the CC81 cat cells transformed with murine sarcoma virus, were used as indicator cells. The syncytium-induction inhibition effect of anti-bovine leukemia virus serum was enhanced significantly by the addition of rabbit complement. The syncytium-induction inhibition titers had a statistically significant correlation with the immunodiffusion titers and were four to 64 times higher than immunodiffusion titers. In 12 experimentally infected cattle, the syncytium-induction inhibition test detected the antibodies earlier than the immunodiffusion test and continuously detected them when immunodiffusion antibody changed to negative. In the 81 sera from naturally infected herds, 35 (43.2%) were positive by the immunodiffusion test and 55 (67.9%) by the syncytium-induction inhibition test.