Espiratory viral infection. The Influenza Factor was applied to the microarray data derived from the blood RNA samples and correctly identifies 92 (33/36) of the subjects asFigure 4. Validation of the Influenza Factor in a real-world cohort of individuals presenting with confirmed swine-origin 2009 A/ H1N1 infection. The Influenza Factor scores distinguish individuals with RT-PCR proven H1N1 infection ( ) from healthy individuals (#) as demonstrated both by factor score and by ROC curve for healthy vs. H1N1 (insert, AUC 0.98). doi:10.1371/journal.pone.0052198.gNHost Genomic Signatures Detect H1N1 Infectioninfected with Novel H1N1, and correctly identified 93 (42/45) of the healthy controls (Fig. 4). Overall, the Influenza Factor performed with an accuracy of 92.3 in the setting of a realworld, independent cohort with pandemic 2009 H1N1 infection.DiscussionWe performed two independent human viral challenge studies (using influenza H1N1 and H3N2) to define the host-based peripheral blood gene expression patterns characteristic of the response to influenza infection. The results Hexaconazole biological activity provide clear evidence that a biologically relevant peripheral blood gene expression signature can distinguish influenza infection with a remarkable degree of accuracy across the two strains. We have also defined the performance of the blood gene expression signature over time throughout the complete course of human influenza infection. Furthermore, despite arising from a controlled experimental challenge setting, we demonstrate that an influenza signature is able to accurately Oltipraz identify individuals presenting with naturallyoccurring, RT-PCR confirmed H1N1 infection during the 2009 pandemic. Defining the etiology of clinical syndromes in which infection is suspected remains challenging. Currently available influenza diagnostic tests exhibit highly variable sensitivity, ranging from 53 to 100 in various studies [19,20]. Importantly, even those with powerful test characteristics such as RT-PCR are dependent upon sampling technique and inclusion of virus-specific components leading to reduced effectiveness with emerging viral strains [21]. In addition to being less susceptible to sampling error, genomic signatures are not viral antigen or nucleic aciddependent, and unlikely to be as strain-specific as pathogen-based platforms. Therefore, in addition to high sensitivity in the cohorts studied [92 (95 CI 79?9 for 2009 H1N1)], influenza gene signatures have the added potential of being able to identify, in the acute phase of illness, likely cases of infection with emerging influenza strains for which a specific diagnostic platform has yet to be developed and distributed. The nature of challenge studies limits our ability to make direct comparisons to other infected states ?however, our previous work has demonstrated that genomic signatures similarly derived from viral challenges are capable of distinguishing upper respiratory viral infection from pneumonia due to Streptococcus pneumoniae [4]. These findings are promising but additional testing of these signatures in other models, including acute human cases of bacterial infection, will need to be performed to better delineate their specificity. The unique design and frequent sampling involved in two experimental challenge studies has also given us the 18325633 singular ability to examine the dynamics of temporal development of the genomic responses following exposure to infectious virus. We have shown that when viewed throu.Espiratory viral infection. The Influenza Factor was applied to the microarray data derived from the blood RNA samples and correctly identifies 92 (33/36) of the subjects asFigure 4. Validation of the Influenza Factor in a real-world cohort of individuals presenting with confirmed swine-origin 2009 A/ H1N1 infection. The Influenza Factor scores distinguish individuals with RT-PCR proven H1N1 infection ( ) from healthy individuals (#) as demonstrated both by factor score and by ROC curve for healthy vs. H1N1 (insert, AUC 0.98). doi:10.1371/journal.pone.0052198.gNHost Genomic Signatures Detect H1N1 Infectioninfected with Novel H1N1, and correctly identified 93 (42/45) of the healthy controls (Fig. 4). Overall, the Influenza Factor performed with an accuracy of 92.3 in the setting of a realworld, independent cohort with pandemic 2009 H1N1 infection.DiscussionWe performed two independent human viral challenge studies (using influenza H1N1 and H3N2) to define the host-based peripheral blood gene expression patterns characteristic of the response to influenza infection. The results provide clear evidence that a biologically relevant peripheral blood gene expression signature can distinguish influenza infection with a remarkable degree of accuracy across the two strains. We have also defined the performance of the blood gene expression signature over time throughout the complete course of human influenza infection. Furthermore, despite arising from a controlled experimental challenge setting, we demonstrate that an influenza signature is able to accurately identify individuals presenting with naturallyoccurring, RT-PCR confirmed H1N1 infection during the 2009 pandemic. Defining the etiology of clinical syndromes in which infection is suspected remains challenging. Currently available influenza diagnostic tests exhibit highly variable sensitivity, ranging from 53 to 100 in various studies [19,20]. Importantly, even those with powerful test characteristics such as RT-PCR are dependent upon sampling technique and inclusion of virus-specific components leading to reduced effectiveness with emerging viral strains [21]. In addition to being less susceptible to sampling error, genomic signatures are not viral antigen or nucleic aciddependent, and unlikely to be as strain-specific as pathogen-based platforms. Therefore, in addition to high sensitivity in the cohorts studied [92 (95 CI 79?9 for 2009 H1N1)], influenza gene signatures have the added potential of being able to identify, in the acute phase of illness, likely cases of infection with emerging influenza strains for which a specific diagnostic platform has yet to be developed and distributed. The nature of challenge studies limits our ability to make direct comparisons to other infected states ?however, our previous work has demonstrated that genomic signatures similarly derived from viral challenges are capable of distinguishing upper respiratory viral infection from pneumonia due to Streptococcus pneumoniae [4]. These findings are promising but additional testing of these signatures in other models, including acute human cases of bacterial infection, will need to be performed to better delineate their specificity. The unique design and frequent sampling involved in two experimental challenge studies has also given us the 18325633 singular ability to examine the dynamics of temporal development of the genomic responses following exposure to infectious virus. We have shown that when viewed throu.
