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Characterization of two divergent adenovirus 31 strains
P A Thörner1, M Ahrel-Andersson, J C Hierholzer
1Department of Clinical Microbiology, Karolinska Hospital, Stockholm, Sweden.
Abstract:
Two divergent strains of adenovirus type 31 were analyzed by neutralization test and restriction endonuclease (RE) patterns in an effort to find the basis for their genetic variability. One strain, isolated from the throat of a child in Maryland during an upper respiratory illness in 1968, was partially neutralized by Ad 31 antisera (to 16-fold lower than homologous titer) while its own antiserum fully neutralized prototype Ad 31 virus, but shared only 9% of comigrating RE fragments with Ad 31 prototype (vs. 30% with Ad 18 prototype); however, PCR tests specific for the inverted terminal repeat (ITR) sequence of Ads 12 and 18 were negative. The other strain, recovered from a stool sample from an infant with diarrhea in Georgia in 1979, was inhibited by Ad 31 antiserum to within 4-fold homologous titer, but shared only 15% of comigrating fragments with Ad 31 prototype (vs. 91% with Ad 18 prototype); ITR-specific PCR tests with this virus were positive for Ad 12/Ad 18. These data suggest that both strains are from separate evolutionary lines of Ad 31 unrelated to all other isolates studied to date by RE analysis, and that the partial neutralization by prototype Ad 31 antisera might represent small mutations in the hexon gene.
Insights
Two adenovirus type 31 strains show genetic variability, suggesting separate evolutionary paths. Analysis revealed distinct restriction endonuclease patterns and differing reactions to neutralization, indicating mutations in the hexon gene.
Area of Science:
- Virology
- Molecular Biology
- Genetics
Background:
- Adenovirus type 31 (Ad 31) exhibits genetic variability.
- Understanding the basis of this variability is crucial for viral characterization.
Purpose of the Study:
- To investigate the genetic variability of two divergent adenovirus type 31 strains.
- To determine the basis for observed genetic differences using neutralization tests and restriction endonuclease (RE) patterns.
Main Methods:
- Neutralization tests using specific antisera.
- Restriction endonuclease (RE) pattern analysis of viral DNA.
- Polymerase chain reaction (PCR) for inverted terminal repeat (ITR) sequence detection.
Main Results:
- One Ad 31 strain (1968, Maryland) showed partial neutralization by Ad 31 antisera and low RE fragment similarity to Ad 31 prototype, with negative ITR PCR for Ads 12/18.
- A second Ad 31 strain (1979, Georgia) showed near-homologous neutralization by Ad 31 antisera but low RE fragment similarity to Ad 31 prototype, with positive ITR PCR for Ad 12/18.
- Both strains exhibited unique RE profiles, suggesting they belong to separate evolutionary lineages distinct from other studied isolates.
Conclusions:
- The two Ad 31 strains represent distinct evolutionary lines, unrelated to other isolates analyzed.
- Partial neutralization by Ad 31 antisera may indicate minor mutations within the hexon gene.
- Genetic variability in Ad 31 is significant and warrants further investigation into evolutionary pathways.