3.4 Thermal stability
According to the criteria whether HA titer would decrease two units after incubated at 56°C for 5 and 30 min, the AIVs can be divided into three types: thermal instability (HA titer decreased two units in 5 min), thermal stability (HA titer decreased two units in 30 min) and moderate thermal stability (in between) (He et al., 2018). The results (Figure 3A) showed that the HA titers of both strains didn’t decrease within 30 min, suggesting they were thermal stable viruses. We could also see that the virus titers of both strains changed to 0 within 15 min (Figure 3B), indicating low infectivity of them. To summarize, incubation of the viruses at 56°C didn’t influence their HA activity too much, but infectivity was significantly reduced.