Comparison of the immunomodulatory capabilities of the V and C proteins of different morbilliviruses

During a viral infection, when the virus enters into the cytoplasm, different cell types are able to produce interferons (IFN) as a result of interaction between intracellular pattern recognition receptors (PRR) and RNA helicases. This interferon activates and establishes an antiviral state which limits further spread of the virus. Morbilliviruses are highly infectious viruses that spread mainly via direct contact. The genome of morbillivirus contains six genes, translated into eight proteins. The morbillivirus P gene is translated, in addition to the P protein, to V and C proteins. These proteins are directly related to inhibiting type I interferon expression and signalling and thus limit transcription of interferon- stimulated genes (ISGs). Previous studies show that V and C proteins of morbilliviruses have an ability to interfere with the type I IFN pathway at different levels, and the V protein is the main inhibitor. This study focuses on the immunomodulatory capability of a newly discovered Feline morbillivirus (FmoPV) in comparison with the wellknown Canine distemper morbillivirus (CDV) of dogs and Measles morbillivirus (MeV) of humans. The V proteins of all the tested viruses strongly inhibited the type I IFN pathway compared to the C proteins. The V and C proteins of FmoPV showed lower immunomodulatory capabilities compared to CDV and MeV. The V protein of CDV showed highest inhibitory ability of tested V proteins and the C protein of the MeV showed the highest inhibitory ability of the tested C proteins. In both cases, significant inhibitory similarities between V and C protein of CDV and MeV were observed.