FIG 4.
Virus titers in the nasal washes of 4-week-old or 8-week-old hamsters infected with 106 PFU of H3N2/2013 (A, left), H3N2/2014 (A, middle), H3N2/2016 (A, right), pdmH1N1/2013 (B, left), pdmH1N1/2014 (B, right), Victoria/2014 (C, left), or Yamagata/2014 (C, right) virus (n = 3 hamsters for each virus). Nasal wash specimens with 400 μl of PBS from each hamster were collected every other day for virus titration. Virus titers were determined by using a plaque assay on MDCK cells. The lower limit of detection is indicated by the horizontal dashed lines.