The meq gene was thought to be only detected in Marek's disease virus serotype 1 (MDV1) including a very virulent strain, Md5, while L-meq, in which a 180-bp sequence is inserted into the meq open reading frame, is found in other strains of MDV1, such as CVI988/R6. However, both meq and L-meq were previously detected by PCR in chickens infected with MDV1, suggesting hat MDV1 may consists of at least two subpopulations, one with meq, the other with L-meq. To further analyze these subpopulations, we analyzed the time course changes in distribution of these subpopulations among T cell subsets from chickens infected with MDV1. Both meq and L-meq were detected in CD4(+) and CD8(+) T cells infected with strain Md5 or CVI988/R6. The shift in MDV subpopulations from one displaying meq to the other displaying L-meq and/or the conversion from meq to L-meq occurred mainly in the CD8(+) T cell subset from Md5- infected chickens. PCR products corresponding to L-meq rather than meq were frequently amplified from the CD8(+) T cell subset from CVI988/R6-infected chickens. These results suggest that a dominant subpopulation of MDV1 changes depending on the T cell subsets, and that L-meq is dominantly present in the CD8(+) T cells which play a role in the clearance of pathogenic agents.

In the conditions of the Republic of Belarus there was realized a comparative studying of immune reactivity of broiler chickens immunized against Marek's disease by means of vaccines of Russian production. In course of the study it was established, that in broiler chickens vaccinated against Marek's disease (by means of cultural dry viral vaccine on the basis a virus of herpes of turkeys FS-126 and by liquid bivalent cultural virus vaccine Bimarek on the basis of strains of a herpes virus of turkeys and a herpes virus of hens) the revealed morphological changes in immune system organs of did not essentially differ and testified to the development of intense postvaccinal immunity. Economic efficiency of immunization of broiler chicken against Marek's disease under production conditions made 4,87 and 2,94 Belarusian roubles per 1 rouble of expenses, respectively. | Целью исследования явилось сравнительное изучение иммунной реактивности организма цыплят-бройлеров, иммунизированных против болезни Марека вакцинами российского производства. В ходе исследований установлено, что у цыплят-бройлеров, вакцинированных против болезни Марека культуральной сухой вирусвакциной из вируса герпеса индеек ФС-126 и жидкой бивалентной культуральной вирусвакциной Бимарек из штаммов вируса герпеса индеек и вируса герпеса кур выявленные морфологические изменения в органах иммунной системы существенно не отличаются и свидетельствуют о выработке напряженного поствакцинального иммунитета. Экономическая эффективность иммунизации цыплят против болезни Марека в производственных условиях составляет 4,87 и 2,94 рубля на 1 рубль затрат соответственно.