[Genetic polymorphism of alkaline phosphatase and the resistance to Marek's disease virus]. / Genetichen polimorfizum na alkalnata fosfataza i ustoichivost na virusa na bolestta na Marek.

Experiments were carried out with a total of 222 birds of the 5-A, 6-E, Ya-73, LL, and LS lines of the White Leghorn breed to find whether or not there existed any correlation between the alkaline phosphatase allels and the resistance to Marek's disease. The polymorphism of alkaline phosphatase was evaluated in the blood plasma of birds through horizontal electrophoresis in starch gel after G a hn e [3]. The resistance of the five egg laying lines of birds was found to be associated with the Akps allel, and their susceptibility - with the AkpF allel. No mortality with the homozygous gene type SS was established in the investigated lines except for a birds of the LL line. It was found that there existed full agreement of the results from the studies on broiler and laying lines concerning the exclusive resistance of birds of Akp SS gene type. This made it reasonable to believe that the indirect selection by resistance to the Marek's disease virus through the use of the Akps allel as a genetic marker was promising.

[Changes in the polymorphism of the blood serum alkaline phosphatase in chickens undergoing subacute lindane treatment]. / Promeni v polimorfizma na alkalnata fosfataza v kruvna plazma na kokoshki pri subakutno tretirane s lindan.

Investigated were a total of 123 birds of the White Leghorn breed and 50 birds of the White Plymouth Rock breed. Preliminary studies were carried out on the LD50 amount of lindane (151 mg/kg body mass) with 6 groups of chickens. The birds were divided into 4 subgroups for each breed. The first subgroup was a control one and was not given lindane, and the remaining subgroups were offered the following amounts of lindane in the course of 5 successive days: II - 1/20 LD50 (7.6 mg/kg daily); III - 1/10 LD50 (15.1 mg/kg); and IV - 1/5 LD50 (30.2 mg/kg). Each single one of the test birds was treated individually by means of a rubber tube and a syringe with a pure substance of lindane dissolved in oil. The polymorphism of alkaline phosphatase in the blood plasms of chickens was determined through horizontal electrophoresis in starch gel after the method of Gahne [14]. It was found that at subacute treatment of the birds a drop off was observed of the S1 fraction, and, as a result, the frequence of the homozygotic alkaline-phosphatase phenotypes FF and SS rose, while that of FS1 and SS1 dropped. Subacute treatment with part of the birds led to the appearance of an additional fraction F1, which accompanied the SS, SS1, and SS2 phenotypes only. The changes that took place as a result of the subacute treatment were only phenotypic ones as the F1 and S1 fractions had no hereditary character.

[Resistance of different breeds of laying poultry to Marek's disease virus]. / Ustoichivost na razlichni linii ptitsi iaitsenosno napravlenie kum virusa na bolestta na Marek.

Investigated were a total of 447 two-day-old chicks of lines 5-A, ia-73' ll and lS of the Leghorn breed divided into 2 groups: controls--99 males and females, and test ones--348 infected at the age of 2 days via intraabdominal injection with 0.4 cm3 heparinized blood each, containing 5000 PFU per dose of the Marek's disease virus (CT-1 isolate). Both linear and sexual variations were found in the resistance of the birds. Most resistant proved to be the 5-A chicks of both sexes, and most susceptible--those of the lS line. No essential differences were observed in the response of the initial lines of broiler birds and the lines of laying birds raised in this country at the intraabdominal infection with the same virus. It was established that the birds of lines 5-A and 6-E of the Canadian Leghorn breed were close in terms of resistance with the birds of lines 66 and 77 of the Cornish breed, while those of the Leghorn lines ll and lS were resembling by resistance the birds of lines 88 and 89 of the White Plymouth Rock broilers which were more susceptible to Marek's disease. It is stated that the cockerels and poults of the ia-73 synthetic line, newly developed in this country, show essentially varying resistance most probably associated with insufficient consolidation.

[Relationship between the genetic polymorphism of alkaline phosphatase and the resistance of broiler poultry to Marek's disease virus]. / Zavisimost mezhdu genetichniia polimorfizum na alkalnata fosfataza i ustoichivostta na ptitsite broilerno napravlenie kum virusa na bolestta na Marek.

Studied was the polymorphism of alkaline phosphatase in blood plasma samples taken from 507 poulets and cocks of lines 66 and 77 of the Cornish breed, and lines 88 and 99 of the White Plymouth Rock breed. The birds were divided into three groups to test their resistance to Marek's disease: (1) controls, (2) infected with the virus of Marek's disease with 3 subgroups--resistant birds, slightly susceptible ones, and strongly susceptible ones, and (3) contacts, with two subgroups--survivals and birds that died. The blood plasma alkaline phosphatase was determined through horizontal electrophoresis on a starch gel, employing the method of Gahne. It was found that the alkaline phosphatase genetype FF frequency was lower with lines 66 and 77 than with line 88 and especially with line 99 of the White Plymouth Rock breed which proved most susceptible to the virus of Marek's disease. In the homozygotic alkaline phosphatase genetype SS none of the investigated lines showed any mortality. The resistance of broiler birds to Marek's disease was governed by the Akps allele, while the susceptibility was governed by the Akpf one. The former could be used as a genetic marker in the selection of initial lines of broiler birds by resistance, and the latter could be used as a marker in the selection by susceptibility.

[Breed, line and sex differences of phagocytic activity in relation to broiler poultry resistance to Marek's disease virus]. / Porodni, lineini i polovi razliki na fagotsitnata aktivnost vuv vruzka s ustoichivostta na ptitsite broilerno napravlenie kum virusa na bolestta na Marek.

The phagocytic activity was studied of 421 poulets and cocks of lines 66 and 77 of the Cornish breed, and lines 88 and 99 of the White Plymouth rock breed. Breed and linear differences were noticed in the changes of the phagocytic activity (phagocytic number and phagocytic index) with birds infected with the virus of Marek's disease. The rise of the phagocytic activity with lines 66 and 77 was slighter as compared with that of the White Plymouth Rock lines 88 and 99. Strongest were the changes in the phagocytic activity with birds that were strongly susceptible to Marek's disease, and slight est--with birds that were resistant to the disease. A trend of a better expressed phagocytic activity was noticed with the cocks of all investigated lines.

[Resistance of broilers to Marek's disease virus]. / Ustoichivost na ptitsite broileri kum virusa na Marekovata bolest.

Studied was the resistance, resp., susceptibility of the initial broiler lines - 66 and 77 of the Cornish breed, and 88 and 99 of the Plymouth Rhock breed, which are used in this country for the production of the four-line hybrid, - to the virus of the Marek's disease, isolate CT-1. A biologic assay was carried out with a total of 2080 young birds divided into three groups; I groups - infected abdominally; II group - contacts; and III group - controls. Certain breed, line, and sex differences were established in terms of resistance, resp., susceptibility of the investigated birds to the CT-1 isolate of the Marek's disease virus. More resistant were the birds of the Cornish breed as compared to those of the White Plymouth Rhock breed. A rising trend was observed in the resistance of cockerels in comparison with the poults of the respective line. Most susceptible to Marek's disease proved the birds of line 99, especially the poults that were currently used for the production of the mother parental form of the four-line hybrid. The birds with abdominal infection showed death cases as early as the second month of age, mortality rising up to end of the fourth month, while with the contacts and controls most death cases were observed at the fifth month of age. Essential decrease in mortality set in with all three groups after the birds reached six months of age. At a low rate of infections which was experimented with the contact and the control group there were not opportunities to fully discover the resistance of birds to Marek's disease.