Characterization of the stunting syndrome agent: physicochemical properties

Stunting syndrome is an enteric disease of turkeys causing diarrhea, reduced weight gain, poor feed efficiency, and maldigestion. The etiologic agent is a newly identified, but unclassified, virus termed the stunting syndrome agent (SSA). The SSA is a pleomorphic, enveloped virus ranging from 60 to 95 nm in diameter. The objectives of this study were to characterize the physicochemical properties of SSA. SSA hemagglutinated rat erythrocytes at 4 C and room temperature. Treatment of SSA with ether resulted in loss of infectivity. SSA was resistant to pH changes between pH 3.0 and pH 9.0 at 37 C for 1 hr. The virus was inactivated at pH > or = 10. SSA was resistant to treatment with trypsin, chymotrypsin, pancreatin, phospholipase C, and sodium deoxycholate. Treatment of SSA with trypsin, chymotrypsin, and pancreatin resulted in enhanced viral infectivity. The viral genome extracted from purified SSA was sensitive to RNAse treatment. Using oligo d(T)16-18 and random hexamers as primers, the SSA genome was amplified using the reverse transcription-polymerase chain reaction conditions but was not amplified using polymerase chain reaction conditions. The enrichment of viral genome was achieved following poly-A+ selection. These studies provide evidence that the SSA is a positive-sense, single-stranded RNA virus having many characteristics (stability at acidic pH, resistant to proteolytic enzymes and bile salt) consistent with other enveloped enteric viruses.