Figure 1: Mutation frequency in A/Anhui/1/13 (H7N9) influenza viruses collected from chickens and ferrets.
From: Mammalian adaptation of influenza A(H7N9) virus is limited by a narrow genetic bottleneck
(a) Heat map showing nucleotide substitutions identified in chicken (oropharyngeal swabs) and ferret (nasal washes) virus isolates by using Illumina Mi Seq. Only mutations with a frequency >0.03 are shown. Numbers on the y axis represent the day post inoculation. (b) Mean variation frequency. Mean variation frequency for each sample was calculated using positions that are variable in at least one of the examined samples. If a site has a minor variant frequency above zero in any of the samples this was included in the nominator and the denominator of the proportion was the total number of variable sites that was variable in all samples. Variation frequency was expressed as the negative log. ‘Donor ferrets Round 1’ are ferrets inoculated with parental A/Anhui/1/13 (H7N9) influenza virus; ‘Other ferrets’ are contact ferrets in round 1 of experiments and donor ferrets in round 2. *P<0.05, two-tailed Mann–Whitney U-test. P, parental virus; D, donor; DC, direct contact; AC, airborne contact.
