Features of pathogenesis in sacbrood virus at honey bees (Apis mellifera L.)

Abstract

Bees and their larvae are prone to various viral diseases, which lead to disruption of the vital activity of the bee colony and sometimes to its death. It is hazardous for the bee colony when a sac-like brood damages it. Sick families differ sharply from healthy ones in terms of their condition and productivity; they develop slowly in the spring and grow few offspring. Adult bees of sick families do not live long; they are not very active, weakly protect nests, fly sluggishly, and are unfriendly to collect honey. Therefore, the work aimed to identify physiological changes in the intestines of sexually mature ewes affected by cystic brood. The experimental part of the work was carried out in the conditions of the Stepan Gzhytskyi National University of Veterinary Medicine and Biotechnologies Lviv. The research was conducted during 2018–2020 at a farm in the Stryi district of the Lviv region. The farm's apiary consisted of 230 bee families. The subjects of the study were fertile uteri aged two years. Signs of virus damage were detected on the farm in 2018 and 2019. The diagnosis was confirmed based on epizootological data, clinical signs, and laboratory studies. By conducting histological studies, data on the pathogenesis of honey bees affected by the virus were supplemented. The data on physiological and morphological changes in the middle intestine of pregnant mothers are given. Histological studies were carried out in different parts of the mid intestine. Changes in the function of the peritrophic membrane were found in sick uteri compared to clinically healthy ones. An increase in the length of the midgut fold in the front part of the intestine by 23% was revealed (Р ˂ 0.001). Under the influence of the pathogenicity of the virus, there is an intensive proliferation of enterocytes in the middle part of the intestine. In the case of damage by a sac-like brood, the work of the membrane-associated with the motor, secretory and other functions of the midgut is disturbed. This, in turn, leads to dystrophic and inflammatory changes in the surface epithelium and also inhibits the regeneration process. Damage to the structural components of the mucous membrane is indicated by the absence of a hypertrophic membrane in the caudal direction of the midgut of sick mothers, where necrotic damage to the mucous membrane up to the basement membrane is revealed.