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Molecular typing of echovirus serotype 4 isolates
U Künkel1, S Diedrich, E Schreier
1Robert Koch-Institut, Berlin, Nordufer 20, D-13353, Berlin, Germany.
Abstract:
We report on clinical samples Stuttgart/97, Berlin/99 and Jasi/99 associated with aseptic meningitis. All three samples contained echovirus 4 (E4) but Stuttgart/97 was simultaneous infected with echovirus 30 (E30). The genetic relationship of the E4 strains was assessed using RT-PCR and direct sequencing of amplicons derived from the genomic region encoding the capsid protein VP1. The sequences have been compared with each other and with sequences of further E4 strains obtained from GenBank. The analysis confirms that sequences of recent isolates have drifted away from elderly strains over a longer period of time. Several amino acid changes in assumed antigenic sites of the VP1 gene may be sufficient to cause changes in antigenic specificity and therefore they may be a reason for failure of serological typing of some new antigenic E4 variants.
Insights
Recent echovirus 4 (E4) strains show genetic drift from older strains, potentially impacting serological typing. This evolution in E4 variants may explain difficulties in identifying new antigenic types.
Area of Science:
- Virology
- Molecular Biology
- Epidemiology
Background:
- Aseptic meningitis can be caused by enteroviruses, including echovirus 4 (E4).
- Clinical samples from Stuttgart/97, Berlin/99, and Jasi/99 were associated with aseptic meningitis.
- Echovirus 4 was detected in all samples, with co-infection of echovirus 30 (E30) in the Stuttgart/97 sample.
Purpose of the Study:
- To genetically analyze echovirus 4 (E4) strains from clinical samples.
- To assess the genetic relationship between recent and older E4 strains.
- To investigate potential reasons for difficulties in serological typing of E4 variants.
Main Methods:
- Reverse transcription-polymerase chain reaction (RT-PCR) was used for amplification.
- Direct sequencing of amplicons from the capsid protein VP1 gene.
- Sequence comparison with E4 strains from GenBank.
Main Results:
- Genetic analysis revealed that recent E4 isolates have diverged from older strains.
- Several amino acid changes were identified in putative antigenic sites of the VP1 gene.
- These changes may alter the antigenic specificity of E4 variants.
Conclusions:
- Echovirus 4 strains have evolved over time, showing genetic drift.
- Amino acid substitutions in VP1 may lead to altered antigenic properties.
- This antigenic variation could explain failures in serological typing of new E4 variants.