The aim of this paper is to identify the difference of type I interferon expression in 2- day neonatal and six-to-eight-weeks adult mice infected by Sendai virus (SeV), a single- stranded RNA virus of the family Paramyxoviridae. Sendai virus mimics the influence of respiratory syncytial virus (RSV) on humans, but does not infect humans. Although RSV has a fatal impact on people across age groups, little is understood about this common virus and the disparity between neonatal and adult immune response to it. It has been suggested by past findings that Type I interferon mRNA is present in higher levels in adults than in neonates, however there is a greater amount of interferon proteins in neonates rather than adults. To test the hypothesis that neonates are more capable of interferon production and preventing the translation of viral protein, I observed mouse models of respiratory viral infection and determined the expression of IFN-α1, IFN-α2, IFN-α5, IFN-α6, IFN-α7, IFN-β in archived mouse lung tissue samples harvested on different days post-infection with quantitative real time PCR. Expression of Glyceraldehyde 3-phosphate dehydrogenase(GAPDH), a housekeeping gene expressed constitutively in all mouse models, was used as a positive control of the experiment. To determine the ideal concentration of primer used in qPCR, primer reconstitution, primer optimization, and gel electrophoresis were conducted in advance. In addition, technical replicates and biological replicates were used to reduce error and confirm results in qPCR. In accordance with previous discovery, I found an upward trend in adults’ interferon expression from post-infection day 1 to day 5, and levels off in day 7. In contrast, neonatal levels were much higher on day 1 and remained high over the course of infection. This explains how type I interferon expression is altered in neonates to help them clear the virus at the same efficiency as adults without causing inflammation. Future research on immune response differences in human infection should focus on the evaluation of interferon protein amounts, as well as the analysis of activation of molecules downstream of the type I interferon receptors, such as signal transducer and activator of transcription (STAT) protein family. It is also crucial to compare immune cells like macrophages and natural killer cell activity in adult and neonatal mice during viral infection.
Intranasal type I interferon treatment is beneficial only when administered before clinical signs onset in the SARS-CoV-2 hamster model
