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Published on: June 16, 2011
Variability in the integrity of human enteroviruses exposed to various simulated in vivo environments
L Piirainen1, T Hovi, M Roivainen
1Enterovirus Laboratory, National Public Health Institute, Helsinki, Finland.
Abstract:
We exposed representatives of different enteroviruses to treatments imitating various in vivo environments that they face during infection. Short-term treatment in trypsin or human intestinal fluid regularly resulted in a cleavage of the capsid protein VP1, and in some cases of other capsid proteins as well. Infectivity of the virus preparations was usually not affected but there were two exceptions. Coxsackievirus A9 retained its infectivity as tested in RD cells but showed reduced infectivity in GMK cells, as reported previously. More strikingly, the titre of echovirus 22 was decreased by 2 logs. Overnight incubation in intestinal fluid affected the infectivity of all tested viruses, including polioviruses and coxsackievirus B4. Echovirus 22 and, to a lesser extent, coxsackievirus A9 were also partially inactivated by faecal suspension. After 2 h exposure to pH 2 at 37 degrees C all tested viruses retained their infectivity, but after 24 h all were inactivated. We conclude that the stability of enteroviruses exposed to various natural environments varies significantly, and that echovirus 22, no more classified in the genus Enterovirus, appears relatively more sensitive in body fluids.
Insights
Enteroviruses showed varied stability in simulated body fluids, with some capsid proteins cleaving. Echovirus 22 demonstrated increased sensitivity in intestinal fluids and fecal suspensions, impacting its infectivity.
Area of Science:
- Virology
- Microbiology
- Infectious Diseases
Background:
- Enteroviruses are a significant group of human pathogens.
- Understanding their stability in various physiological environments is crucial for infection control and treatment strategies.
Purpose of the Study:
- To investigate the stability and infectivity of different enteroviruses under simulated in vivo conditions.
- To assess the impact of environmental factors like digestive enzymes, intestinal fluids, and pH on enterovirus integrity.
Main Methods:
- Exposure of enterovirus strains to trypsin, human intestinal fluid, and fecal suspension.
- Incubation at low pH (pH 2) at 37°C for varying durations.
- Analysis of capsid protein integrity (VP1 cleavage) and viral infectivity (titration).
Main Results:
- Short-term exposure to trypsin or intestinal fluid caused capsid protein VP1 cleavage in most enteroviruses.
- Echovirus 22 showed a significant 2-log decrease in infectivity after intestinal fluid treatment.
- Overnight incubation in intestinal fluid reduced infectivity of all tested viruses, including polioviruses and coxsackievirus B4.
- Echovirus 22 and Coxsackievirus A9 were partially inactivated by fecal suspension.
- All viruses retained infectivity after 2 hours at pH 2 but were inactivated after 24 hours.
Conclusions:
- Enterovirus stability varies considerably across different physiological environments.
- Echovirus 22, now reclassified, exhibits heightened sensitivity to human body fluids compared to other enteroviruses.
- These findings highlight the importance of environmental factors in enterovirus survival and pathogenesis.
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