Analysis on viral load, drug resistance and specific antibody level of a human case infected with influenza A (H7N9) virus in Beijing

Objective To understand the changes of the viral load, antibody level and drug resistance during illness of human infection with influenza A (H7N9). Methods A total of 25 bronchoalveolar lavage fluids and 23 blood samples were collected from 1 case of infection with influenza A (H7N9) virus in Beijing at interval of 24 hours. Real-time RT-PCR was performed to evaluate the viral load of H7N9 virus and determine the R294K mutation in NA protein. Hemagglutination inhibition test was conducted to evaluate the H7N9 virus specific antibody level. Results Along with the disease progress and antiviral therapy, the viral loads of H7N9 virus decreased gradually, meanwhile the titer of H7N9 virus specific antibody increased. Mild R294K mutation occurred in NA protein in some samples in late phase. Conclusion Quantitative real-time RT-PCR assay and hemagglutination-inhibition test can be used to monitor the changes of viral load, drug resistance and the specific antibody level of H7N9 virus infected persons in clinical treatment.