• No, they did not just prove that cold weather causes colds

    First of all, was this a randomized controlled trial of people getting colds? No? Let’s just get that out of the way. So stop with the causality.

    Temperature-dependent innate defense against the common cold virus limits viral replication at warm temperature in mouse airway cells“:

    Most isolates of human rhinovirus, the common cold virus, replicate more robustly at the cool temperatures found in the nasal cavity (33–35 °C) than at core body temperature (37 °C). To gain insight into the mechanism of temperature-dependent growth, we compared the transcriptional response of primary mouse airway epithelial cells infected with rhinovirus at 33 °C vs. 37 °C. Mouse airway cells infected with mouse-adapted rhinovirus 1B exhibited a striking enrichment in expression of antiviral defense response genes at 37 °C relative to 33 °C, which correlated with significantly higher expression levels of type I and type III IFN genes and IFN-stimulated genes (ISGs) at 37 °C. Temperature-dependent IFN induction in response to rhinovirus was dependent on the MAVS protein, a key signaling adaptor of the RIG-I–like receptors (RLRs). Stimulation of primary airway cells with the synthetic RLR ligand poly I:C led to greater IFN induction at 37 °C relative to 33 °C at early time points poststimulation and to a sustained increase in the induction of ISGs at 37 °C relative to 33 °C. Recombinant type I IFN also stimulated more robust induction of ISGs at 37 °C than at 33 °C. Genetic deficiency of MAVS or the type I IFN receptor in infected airway cells permitted higher levels of viral replication, particularly at 37 °C, and partially rescued the temperature-dependent growth phenotype. These findings demonstrate that in mouse airway cells, rhinovirus replicates preferentially at nasal cavity temperature due, in part, to a less efficient antiviral defense response of infected cells at cool temperature.

    So let’s unpack this. They took mouse airway epithelial cells and infected them with rhinovirus in the lab. Then they checked to see how well the virus was able to replicate itself in those cells at both 37 °C and 33 °C (98.6 °F versus 91.4°F).

    THAT’S NOT COLD WEATHER.

    That’s the difference between the temperature at the core of your body and the temperature in your nose, likely. Cause it’s colder in your nostrils than deep in your body. And it turns out that rhinovirus replicates better in your nostrils than in the core of your body. It prefers a balmy 91.4°F to a toasty 98.6°F.

    It’s cells. Of mice. In the lab. In controlled environments. Measuring only viral replication. At temperatures nowhere near what we’d define as “cold”. This is not proof – in any way – that cold weather makes it more likely for you to catch a cold.

    @aaronecarroll

     

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