Effect of freezing treatment on colostrum to prevent the transmission of bovine leukemia virus.
Here, we used a sheep bioassay to determine the effect of freezing colostrum to prevent the transmission of bovine leukemia virus (BLV) among neonatal calves. Leukocytes were isolated from the colostrum of a BLV-infected Holstein cow and were then either left untreated (control) or freeze-thawed. A sheep inoculated intraperitoneally with the untreated leukocytes was infected with BLV at 3 weeks after inoculation, whereas the sheep inoculated with treated leukocytes did not become infected. The uninfected sheep was inoculated again with leukocytes isolated from the colostrum of another BLV-infected Holstein cow after freezing treatment, and again it did not become infected with BLV. Finally, this sheep was inoculated with the leukocytes isolated from the colostrum of another virus-infected cow without freezing treatment, and it became infected with BLV at 4 weeks after inoculation. The results indicate that colostrum should be frozen as a useful means of inactivating the infectivity of BLV-infected lymphocytes.
Exotic Disease Research Division, National Institute of Animal Health, 6-20-1 Josuihoncho, Kodaira, Tokyo 187-0022, Japan.
Toru
T
Kanno
Ryoko
R
Ishihara
Shinichi
S
Hatama
Yasuhiro
Y
Oue
Hiroki
H
Edamatsu
Yasuhiro
Y
Konno
Satoshi
S
Tachibana
Kenji
K
Murakami
D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000517:prevention & control / Q000635:transmission / Q000821:virology*; D003126:Colostrum / Q000166:cytology* / Q000821:virology; D016583:Enzootic Bovine Leukosis / Q000517:prevention & control* / Q000635:transmission*; D005615:Freezing; D001909:Leukemia Virus, Bovine / Q000472:pathogenicity*; D007962:Leukocytes / Q000821:virology*; D012756:Sheep