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The authentic sequence of rotavirus SA11 nonstructural protein NSP4
P Tian1, A Ottaiano, P A Reilly
1Viral Vaccine Research, Wyeth-Lederle Vaccines, Building 180/216-16, 401 North Middleton Road, Pearl River, NY 10965, USA. tianp@war.wyeth.com
Virus Research
|March 22, 2000
Summary
A single amino acid change in rotavirus nonstructural protein 4 (NSP4) significantly impacts its function. The histidine variant (NSP4-His47) shows increased cell toxicity and calcium flux compared to the asparagine variant (NSP4-Asn47).
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- Rotavirus nonstructural protein 4 (NSP4) acts as an enterotoxin and is crucial for viral pathogenesis.
- Previous in vitro studies utilized a specific cDNA clone of rotavirus gene 10 from the SA11 strain.
- A discrepancy was noted between the commonly used NSP4 cDNA sequence and sequences from SA11 isolates.
Purpose of the Study:
- To investigate the functional impact of an amino acid difference at position 47 in rotavirus NSP4.
- To compare the effects of asparagine (Asn47) versus histidine (His47) at this position on NSP4 function.
Main Methods:
- Direct sequencing of reverse transcription polymerase chain reaction products from SA11 isolates.
- Comparison of NSP4 cDNA sequences.
- Analysis of intracellular calcium regulation and cell cytotoxicity of NSP4 variants using recombinant baculovirus expression.
Main Results:
- A single codon difference was identified, leading to an amino acid substitution at position 47 (asparagine in cDNA vs. histidine in SA11 isolates).
- Expression of NSP4-His47 demonstrated enhanced cytotoxicity compared to NSP4-Asn47.
- NSP4-His47 exhibited increased calcium flux within cells.
Conclusions:
- The amino acid at position 47 of rotavirus NSP4 critically influences its enterotoxic activity.
- The histidine variant (His47) possesses greater cytotoxic potential and calcium-regulating ability than the asparagine variant (Asn47).
- This finding has implications for understanding rotavirus pathogenesis and the role of NSP4 variations.
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