Alkaline phosphatase activity in serum of guinea fowl bearing bone tumours induced by osteopetrosis virus strain PTS-56

Alkaline phosphatase (AP) activities of sera from guinea fowl infected with osteopetrosis virus strain PTS-56 were investigated. Enzyme activities in birds of infected and control groups varied. AP activities in control guinea fowls, 10 to 15 weeks of age, were twice as high as those of 1-year-old birds whose growth was completed. A positive correlation was found between the intensity of virus-induced excessive bone growth and serum AP activity, which was 628 +/- 68.9 microM by the 17th week and reached 1283 + 76.8 microM by the 30th week post-infection (p.i.). Later AP activity decreased, but even at 52 weeks p.i. it was higher than that of untreated guinea fowl. The presumed high proportion of AP of bone origin of the total serum enzyme activities was supported by the low values of residual AP activity after heat inactivation at 58 degrees C (14.7 +/-3.7%) and after precipitation with wheat germ lectin (13 +/-1.2%) during the period of active bone tumour formation.