Avian Paramyxoviruses: Detection by Transmission Electron Microscopy Techniques

Abstract

SUMMARY:Diseases caused by avian paramyxovirus (APMV) occur in commercial, captive and wild birds worldwide, demonstrating the significant economic and ecological importance of these agents. Paramyxoviruses belong to the Paramyxoviridae family, Paramyxovirinae subfamily and Avulavirus genus. During the period 2000 to 2011, stool and small intestine samples of 1647 birds species were sent to the Laboratory of Electron Microscopy, Biological Institute of São Paulo, Brazil, for diagnosis of viral agents. The samples were processed by negative staining (rapid preparation) and resin embedding techniques. Under the transmission electron microscope by negative staining technique, in 294 (17.8%) samples of 1647 were visualized paramyxovirus particles pleomorphic, roughly spherical or filamentous, measuring 100 to 500 nm of diameter containing an envelope covered with spikes and characteristic helical herring-bone-like nucleocapsid measuring 15 to 20 nm in diameter. Ultrathin sections of the small intestine fragments revealed the presence of amorphous granular intracytoplasmic inclusions surrounded by membrane and containing viral nucleocapsid measuring 10-14 nm in diameter. Immature particles budding from cell membranes, pleomorphic, spherical and tubular particles containing viral nucleocapsid strands, and the complete particles measured up to 170 nm in diameter were seen in the cytoplasm. Intranuclear inclusions containing viral nucleocapsid were also visualized. Nuclei showed a marginalized chromatin.

Tracking viral particles in the intestinal contents of the American bullfrog, Lithobates catesbeianus, by Transmission Electron Microscopy

“…The morphological features observed were also reported in other studies such as: birds (Catroxo et al, 2012), frogs 2003), mammals and ferrets (Gregori et al, 2010). Some animals can be asymptomatic carriers of viruses and, upon impairment of immunity, can initiate a viral process.…”

Pathological and molecular findings of avian avulavirus type 1 outbreak in pigeons (Columba livia) of southern Brazil

“…These may consist of apathy, anorexia, weight loss, prostration, diarrhea, polyuria, conjunctivitis, periocular edema, ruffled feathers, sneezing, dyspnea, incoordination, lack of balance, tremors, dehydration, proventricular dilatation, crop emptying problems, leukopenia and death. Some other symptomatic and asymptomatic birds had sudden death (Clavijo et al 2000, Catroxo et al 2012. Brazil has the status of free of pathogenic NDV in commercial poultry, and in the suspect of the disease the notification to the official veterinary service in the country is mandatory (Brasil 2007, Orsi et al 2010.…”

Characterization of avian paramyxovirus type 6 isolated from a Eurasian teal in the intersection of migratory flyways in Russia

“…We first examined the virion of allantoic-grown APMV-6 virus, using electron microscopy. The morphology of virions was found to be typical for paramyxoviruses: enveloped, sphere-shaped and pleomorphic [5] (Fig. 1).…”