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Norwalk virus shedding after experimental human infection.

Atmar RL, Opekun AR, Gilger MA, Estes MK, Crawford SE, Neill FH, Graham DY - Emerging Infect. Dis. (2008)

Bottom Line: Noroviruses are the most common cause of viral gastroenteritis in the United States.Of 16 persons, clinical gastroenteritis (watery diarrhea and/or vomiting) developed in 11; symptomatic illness lasted 1-2 days.Understanding of the relevance of prolonged fecal norovirus excretion must await the development of sensitive methods to measure virus infectivity.

View Article: PubMed Central - PubMed

Affiliation: Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, USA. ratmar@bcm.tmc.edu

ABSTRACT
Noroviruses are the most common cause of viral gastroenteritis in the United States. To determine the magnitude and duration of virus shedding in feces, we evaluated persons who had been experimentally infected with Norwalk virus. Of 16 persons, clinical gastroenteritis (watery diarrhea and/or vomiting) developed in 11; symptomatic illness lasted 1-2 days. Virus shedding was first detected by reverse transcription-PCR (RT-PCR) 18 hours after participant inoculation and lasted a median of 28 days after inoculation (range 13-56 days). The median peak amount of virus shedding was 95 x 10(9) (range 0.5-1,640 x 10(9)) genomic copies/g feces as measured by quantitative RT-PCR. Virus shedding was first detected by antigen ELISA approximately 33 hours (median 42 hours) after inoculation and lasted 10 days (median 7 days) after inoculation. Understanding of the relevance of prolonged fecal norovirus excretion must await the development of sensitive methods to measure virus infectivity.

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Correlation of viral RNA titer with antigen ELISA (optical density [OD]). Titers of viral RNA are correlated with the OD measured by antigen ELISA for the 148 fecal samples with positive quantitative reverse transcription–PCR (qRT-PCR) results (r2 = 0.823, Spearman correlation, p<0.001).
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Figure 2: Correlation of viral RNA titer with antigen ELISA (optical density [OD]). Titers of viral RNA are correlated with the OD measured by antigen ELISA for the 148 fecal samples with positive quantitative reverse transcription–PCR (qRT-PCR) results (r2 = 0.823, Spearman correlation, p<0.001).

Mentions: Norwalk virus concentration in feces, as measured by qRT-PCR, peaked a median of 4 days after inoculation; the time of peak shedding was similar for participants who did and did not meet the definition of viral gastroenteritis (Table). The highest fecal concentrations of virus were detected in 11 (69%) participants after their clinical signs had resolved. The median peak amount of virus shedding was 95 × 109 (range 0.5–1,640 × 109) genomic copies/g feces, and 5 participants shed >100 × 106 copies/g until at least day 14 (Figure 1). Persons who met the clinical definition of gastroenteritis had a higher median peak of virus shedding than those who did not have gastroenteritis (250 × 109 vs. 12 × 109 genomic copies/g feces, p = 0.08, Wilcoxon rank sum), and the average total number of viral genomic copies measured in the feces over the first 2 weeks after inoculation also was higher in the clinical gastroenteritis group (1013.3 vs. 1012.4, p = 0.056, Student t test). The virus concentrations in feces collected later after inoculation were low (range 225,000–40 × 106 genomic copies/g). Correlation between virus titer in feces and optical density results obtained in the antigen ELISA was strong (r = 0.823, Pearson correlation, p<0.001; Figure 2).


Norwalk virus shedding after experimental human infection.

Atmar RL, Opekun AR, Gilger MA, Estes MK, Crawford SE, Neill FH, Graham DY - Emerging Infect. Dis. (2008)

Correlation of viral RNA titer with antigen ELISA (optical density [OD]). Titers of viral RNA are correlated with the OD measured by antigen ELISA for the 148 fecal samples with positive quantitative reverse transcription–PCR (qRT-PCR) results (r2 = 0.823, Spearman correlation, p<0.001).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2609865&req=5

Figure 2: Correlation of viral RNA titer with antigen ELISA (optical density [OD]). Titers of viral RNA are correlated with the OD measured by antigen ELISA for the 148 fecal samples with positive quantitative reverse transcription–PCR (qRT-PCR) results (r2 = 0.823, Spearman correlation, p<0.001).
Mentions: Norwalk virus concentration in feces, as measured by qRT-PCR, peaked a median of 4 days after inoculation; the time of peak shedding was similar for participants who did and did not meet the definition of viral gastroenteritis (Table). The highest fecal concentrations of virus were detected in 11 (69%) participants after their clinical signs had resolved. The median peak amount of virus shedding was 95 × 109 (range 0.5–1,640 × 109) genomic copies/g feces, and 5 participants shed >100 × 106 copies/g until at least day 14 (Figure 1). Persons who met the clinical definition of gastroenteritis had a higher median peak of virus shedding than those who did not have gastroenteritis (250 × 109 vs. 12 × 109 genomic copies/g feces, p = 0.08, Wilcoxon rank sum), and the average total number of viral genomic copies measured in the feces over the first 2 weeks after inoculation also was higher in the clinical gastroenteritis group (1013.3 vs. 1012.4, p = 0.056, Student t test). The virus concentrations in feces collected later after inoculation were low (range 225,000–40 × 106 genomic copies/g). Correlation between virus titer in feces and optical density results obtained in the antigen ELISA was strong (r = 0.823, Pearson correlation, p<0.001; Figure 2).

Bottom Line: Noroviruses are the most common cause of viral gastroenteritis in the United States.Of 16 persons, clinical gastroenteritis (watery diarrhea and/or vomiting) developed in 11; symptomatic illness lasted 1-2 days.Understanding of the relevance of prolonged fecal norovirus excretion must await the development of sensitive methods to measure virus infectivity.

View Article: PubMed Central - PubMed

Affiliation: Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, USA. ratmar@bcm.tmc.edu

ABSTRACT
Noroviruses are the most common cause of viral gastroenteritis in the United States. To determine the magnitude and duration of virus shedding in feces, we evaluated persons who had been experimentally infected with Norwalk virus. Of 16 persons, clinical gastroenteritis (watery diarrhea and/or vomiting) developed in 11; symptomatic illness lasted 1-2 days. Virus shedding was first detected by reverse transcription-PCR (RT-PCR) 18 hours after participant inoculation and lasted a median of 28 days after inoculation (range 13-56 days). The median peak amount of virus shedding was 95 x 10(9) (range 0.5-1,640 x 10(9)) genomic copies/g feces as measured by quantitative RT-PCR. Virus shedding was first detected by antigen ELISA approximately 33 hours (median 42 hours) after inoculation and lasted 10 days (median 7 days) after inoculation. Understanding of the relevance of prolonged fecal norovirus excretion must await the development of sensitive methods to measure virus infectivity.

Show MeSH
Related in: MedlinePlus