Depression is one of the most important causes of disability and loss of useful life of people around the world. Acute respiratory infection caused a large number of severe illnesses and deaths of the world and most of these due to viral infections, which is estimated more than 80% of respiratory infections. Detection of viruses by immune pathogen recognition receptors activates the intracellular signaling cascade and eventually cause produces interferons. Inflammatory process begins with secretion of interferons and the expression of interferon-stimulated genes. One of the most important of these genes is indoleamine-pyrrole 2,3-dioxygenase (IDO), which plays a major role in tryptophan catabolism. IDO is an intracellular monomeric enzyme that is also responsible for breaking down and consuming tryptophan in the Kynurenine pathway. Increased inflammation has been linked to decrease tryptophan concentrations and increase kynurenine levels. We tried to explain the role of inflammation by viral respiratory infections in causing depression.

Respiratory viruses have led to many deaths and hospitalizations per year in the world. The influenza virus is one of the most important respiratory viruses. Recently, metabolic studies in viral infections have been widely studied by scientists.Metabolomics states the metabolites present in a living organism under certain conditions. In this study, peripheral blood mononuclear cells were spinoculated using a virus produced by the Madin-Darby canine kidney cell culture system, and cells were harvested following spinoculation by the influenza virus. Isolation of peripheral blood mononuclear cells was performed by Ficoll-Paque density gradient centrifugation.Metabolites were extracted using organic and water approaches. Metabolic profiling was performed by a nontargeted technique using liquid chromatography with tandem mass spectrometry. Multivariate analysis methods were used to determine the main variables. the metabolic pathways involved were determined using databases. Results of the present study showed changes in biosynthesis pathways such as lipids, polyamines, catecholamines, and vitamins. Findings also showed that it is possible to