Second, the expression levels of autophagy-, immune-, and apoptosis-related genes at 30°C and 37°C were compared to explore factors affecting HuNoV replication. HuNoV cultured at 37°C showed significantly increased autophagy-related genes (
ATG5
and
ATG7
) and immune-related genes (
IFNA
,
IFNB
,
ISG15,
and
NFKB
) compared to mock. However, the virus cultured at 30°C showed significantly decreased expression of autophagy-related genes (
ATG5
and
ATG7
), but not significantly different major immune-related genes (
IFNA
,
ISG15,
and
NFKB
) compared to mock. Importantly, expression of the transcription factor
FOXO1
, which controls autophagy- and immune-related gene expression, was significantly lower at 30°C. Moreover,
FOXO1
inhibition in temperature-optimized MDCK cells enhanced HuNoV replication, highlighting
FOXO1
inhibition as an approach for successful virus replication. In the temperature-optimized cells, various HuNoV genotypes were successfully replicated, with GI.8 showing the highest replication levels followed by GII.1, GII.3, and GII.4. Furthermore, ultrastructural analysis of the infected cells revealed functional HuNoV replication at low temperature, with increased cellular apoptosis and decreased autophagic vacuoles. In conclusion, temperature-optimized MDCK cells can be used as a convenient culture model for HuNoV replication by inhibiting
FOXO1
and providing adaptability to different genotypes.