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Human Astroviruses: A Tale of Two Strains
Virginia Hargest1, Amy E Davis1,2, Shaoyuan Tan1
1Department of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
Abstract:
Since the 1970s, eight closely related serotypes of classical human astroviruses (HAstV) have been associated with gastrointestinal illness worldwide. In the late 2000s, three genetically unique human astrovirus clades, VA1-VA3, VA2-VA4, and MLB, were described. While the exact disease associated with these clades remains to be defined, VA1 has been associated with central nervous system infections. The discovery that VA1 could be grown in cell culture, supports exciting new studies aimed at understanding viral pathogenesis. Given the association of VA1 with often lethal CNS infections, we tested its susceptibility to the antimicrobial drug, nitazoxanide (NTZ), which we showed could inhibit classical HAstV infections. Our studies demonstrate that NTZ inhibited VA1 replication in Caco2 cells even when added at 12 h post-infection, which is later than in HAstV-1 infection. These data led us to further probe VA1 replication kinetics and cellular responses to infection in Caco-2 cells in comparison to the well-studied HAstV-1 strain. Overall, our studies highlight that VA1 replicates more slowly than HAstV-1 and elicits significantly different cellular responses, including the inability to disrupt cellular junctions and barrier permeability.
Insights
Nitazoxanide (NTZ) effectively inhibits the replication of novel human astrovirus VA1, a pathogen linked to central nervous system infections. This antiviral shows promise for treating infections caused by this emerging astrovirus strain.
Area of Science:
- Virology
- Infectious Diseases
- Antimicrobial Research
Background:
- Classical human astroviruses (HAstV) cause gastrointestinal illness worldwide.
- Novel astrovirus clades (VA1-VA3, VA2-VA4, MLB) emerged in the late 2000s.
- VA1 is associated with central nervous system infections, necessitating further study.
Purpose of the Study:
- To investigate the antiviral susceptibility of VA1 to nitazoxanide (NTZ).
- To compare VA1 replication kinetics and cellular responses with classical HAstV-1.
- To assess NTZ efficacy against VA1, particularly in later infection stages.
Main Methods:
- Cell culture experiments using Caco2 cells to grow and study VA1.
- Antiviral susceptibility testing of VA1 with nitazoxanide (NTZ).
- Comparative analysis of VA1 and HAstV-1 replication kinetics and cellular responses.
Main Results:
- Nitazoxanide (NTZ) inhibited VA1 replication in Caco2 cells, even when administered 12 hours post-infection.
- VA1 demonstrated slower replication kinetics compared to HAstV-1.
- VA1 infection induced distinct cellular responses, notably failing to disrupt cellular junctions or barrier permeability.
Conclusions:
- Nitazoxanide (NTZ) is a potential therapeutic agent against VA1 infections.
- VA1 exhibits unique replication and cellular interaction mechanisms compared to classical HAstV.
- Further research into VA1 pathogenesis and NTZ efficacy is warranted.
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