Attempts to Reproduce a Runting/Stunting-Type Syndrome Using Infectious Agents Isolated from Affected Mississippi Broilers

Abstract

Various organisms, including 12 aerobic and 2 anaerobic bacteria, an infectious bronchitis virus (IBV), a reovirus, and 2 bacteriophages, were isolated from intestinal tracts of commercial broiler chicks undergoing a runting/stunting-type condition. In a series of trials, these agents were given alone and in combination to 1-day-old chicks in an attempt to reproduce the field condition. Because the agents were isolated and evaluated over time, an augmented designs variation of the analysis of variance proved particularly useful in analyzing the data collected and minimizing bird usage. Chicks inoculated with tryptose phosphate broth served as negative controls, and those inoculated with the original intestinal tract material were positive controls. Relative to the negative control chicks, body weights of the positive control chicks and of chicks inoculated with several of the agent combinations were depressed at 7, 14, and 21 days postinoculation. Common to combinations that most consistently caused weight depression were reovirus + IBV + others of the agents isolated. However, because none of the agent combinations reproduced the lethargy or dry feces seen in the positive controls, none was considered to be the ultimate cause of this particular runting/stunting-type condition. Further characterization of the disease syndrome was based on the positive control chicks. These chicks consistently had lowered body weights and transient lethargy and dry fecal pellets. Microscopic lesions consisted of lymphocytic renal and pancreatic interstitial infiltrates, dilated or cystic duodenal and jejunal crypts of Lieberkühn, increased crypt depth, and increased cellularity in the intestinal lamina propria. Electron microscopy revealed regular arrays of 26-nm viral particles, usually in association with membrane debris, in intestinal epithelial cells and crypt lumens and in intestinal and renal mesenchymal cells. These viral particles were theorized to be essential to reproduction of the complete malady seen.

The genomic constellation of a novel avian orthoreovirus strain associated with runting-stunting syndrome in broilers

“…The role of infections, toxins, and environmental factors during brooding has been implicated in the development of RSS, and the synergism of various factors cannot be excluded. In fact, numerous viral pathogens have been identified in RSS outbreaks, including rotavirus, parvovirus, astrovirus, enterovirus, and ARV [27][28][29][30][31][32][33]. Although there are data suggesting that additional ARV strain diversity may exist among strains isolated from RSS of broilers [Palya and Bányai, unpublished; Sellers et al, GenBank entries, unpublished], the recent findings by independent research groups that ARV strains carrying a novel genotype of rC protein from RSS can be identified seem to be of interest and warrant the pursuit of further studies in this area.…”

Malabsorption syndrome in broilers

“…Some groups suggest that the syndrome is not specific for any disease (Goodwin et al, 1993;Montgomery et al, 1997) Meanwhile other groups agree that it is an infectious disease because of its transmissible nature (Olsen, 1977;Kouwenhoven et al, 1978b). The MAS aetiology is mainly associated with pathological changes of the gut.…”

“…Several bacteria have been associated with the syndrome as well, like Escherichia coli, Proteus micabilis, Enterecoccus faecium, Staphylococcus cohnii, Clostridium perfringes, Bacteroides fragilis and Bacillus licheniformis (Montgomery et al, 1997). However, most of them can also be present in the microflora of the GI-tract of healthy chickens.…”

“…Smart et al (1988) stated that bacteria alone did not cause MAS. Montgomery et al (1997) attempted to reproduce MAS in one-day-old chicken by using several combinations of agents isolated from MAS affected chickens. Although they could reproduce weight gain depression, the intestinal lesion was not the same as found in MAS chickens.…”

Isolamento e propagação de Astrovírus, Adenovírus, Coronavírus, Parvovírus, Rotavírus e Reovírus de aves comerciais com problemas entéricos em ovos embrionados

“…Em situações de campo, estas infecções podem se agravar pela ação de outros agentes infecciosos como bactérias e protozoários, assim como,condições de manejo, ambiente e nutrição (MONTGOMERY et al, 1997, GUY, 1998.…”