Detection of intranuclear inclusion bodies in hepatocytes of the poultry infected with fowl adenoviruses (Adenoviridae: Aviadenovirus).

Abstract

Introduction: Fowl adenoviruses (FAdV) are infectious pathogens causing significant economic losses in poultry industry. Molecular, pathoanatomic, and pathomorphological methods are used for laboratory diagnosis of FAdV infection. The clinical picture and postmortem lesions are not sufficient to diagnose, unlike histological analysis. Histological examination reveals basophilic intranuclear inclusion bodies considered a pathognomonic sign of FAdV infection. Despite the informative value of the histological method, it has a limitation - the long duration of the procedure, which ranges from 5 to10 days, or, in some cases, several weeks. The aim of this study is to conduct a comparative analysis of pathohistological and pathomorphological changes in the liver cells of chicks infected with avian adenovirus type E, and to develop a cytological diagnostic method based on the preparation and staining of smear imprints to detect, under a microscope, specific inclusions in hepatocytes, which are a pathognomonic sign of avian adenovirus infections.

Materials and methods: Liver samples collected from intact and infected with field FAdV-E isolate 13-day-old SPF chicken embryos were used for preparation of histological sections and imprint smears.The imprint smears were stained with azure-eosin for 60 minutes, and conventionally Gram stained. Microscopy was performed in transmitted light at magnifications ranging from ×80 to ×1000.

Results: Characteristic basophilic intranuclear inclusion bodies (large, blue-violet, rounded inclusion bodies) were detected in histological sections. In the Romanowsky-Giemsa stained imprint smears, the inclusion bodies were also detected within the areas of hepatocyte lysis. When Gram staining was used, the basophilic staining of both lymphocyte nuclei and inclusion bodies made their identification difficult.

Conclusion: Microscopy of liver imprint smears stained according to Romanowsky-Giemsa is promising method due to its simplicity, time efficiency, lower reagent and equipment costs.