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. 2015 Jan;62:8-13.
doi: 10.1016/j.jcv.2014.11.018. Epub 2014 Nov 18.

Blood MxA Protein as a Marker for Respiratory Virus Infections in Young Children

Free PMC article

Blood MxA Protein as a Marker for Respiratory Virus Infections in Young Children

Laura Toivonen et al. J Clin Virol. .
Free PMC article


Background: Type I interferon induced MxA response can differentiate viral from bacterial infections, but MxA responses in rhinovirus or asymptomatic virus infections are not known.

Objective: To study MxA protein levels in healthy state and during respiratory virus infection of young children in an observational prospective cohort.

Study design: Blood samples and nasal swabs were collected from 153 and 77 children with and without symptoms of respiratory infections, respectively. Blood MxA protein levels were measured by an enzyme immunoassay and PCR methods were used for the detection of respiratory viruses in nasal swabs.

Results: Respiratory viruses were detected in 81% of symptomatic children. They had higher blood MxA protein levels (median [interquartile range]) than asymptomatic virus-negative children (695 [345-1370] μg/L vs. 110 [55-170] μg/L; p < 0.001). Within asymptomatic children, no significant difference was observed in MxA responses between virus-positive and virus-negative groups. A cut-off level of 175 μg/L had 92% sensitivity and 77% specificity for a symptomatic respiratory virus infection. Rhinovirus, respiratory syncytial virus, parainfluenza virus, influenza virus, coronavirus, and human metapneumovirus infections were associated with elevated MxA responses. Asymptomatic virus-negative children vaccinated with a live virus vaccine had elevated MxA protein levels (240 [120-540] μg/L), but significantly lower than children with an acute respiratory infection, who had not received vaccinations (740 [350-1425] μg/L; p<0.001).

Conclusion: Blood MxA protein levels are increased in young children with symptomatic respiratory virus infections, including rhinovirus infections. MxA is an informative general marker for the most common acute virus infections.

Keywords: Interferon; MxA protein; Respiratory virus infection; Rhinovirus; Rotavirus vaccine; STEPS study.


Fig. 1
Fig. 1
Blood MxA protein levels in children according to virus detection and presence of symptoms, and in asymptomatic adults. Boxes show median and IQR, and whiskers show 10th and 90th percentiles. Values below the sensitivity limit of 10 μg/L are presented as 7 or 5 μg/L. Values above different groups indicate the ratios of values above the cut-off level of 175 μg/L.
Fig. 2
Fig. 2
Blood MxA protein levels in relation to the duration of fever or respiratory symptoms before MxA measurement. All symptomatic children with recorded duration of symptoms for 1–14 days and with (n = 103) or without (n = 21) detected virus are included. Spearman's rho −0.193; p 0.032; correlation line (– – –); 175 μg/L cut-off (- - -).
Fig. 3
Fig. 3
Blood MxA protein levels in symptomatic virus-positive children according to detected viruses. Boxes show median and IQR, and whiskers show 10th and 90th percentiles. Values above different groups indicate the ratios of values above the cut-off level of 175 μg/L. HBoV, human bocavirus; RV, rhinovirus; CoV, coronavirus; HMPV, human metapneumovirus; PIV, parainfluenza virus (types 1–3); RSV, respiratory syncytial virus; Flu, influenza virus (A or B). A single case with adenovirus is not presented.
Fig. 4
Fig. 4
Blood MxA protein levels and virus findings in the same individuals during the healthy state and during a respiratory infection. Median and IQR values are shown above the groups; p 0.001 by the Mann–Whitney U test. HBoV, human bocavirus; RV, rhinovirus; HMPV, human metapneumovirus; CoV, coronavirus; PIV2, parainfluenza virus type 2; RSV, respiratory syncytial virus; FluA, influenza A virus.

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