Role of interferon gamma in the control of mouse cytomegalovirus infection in neurons

Cytomegalovirus (CMV) is a highly prevalent β-herpesvirus that infects the majority of the population worldwide. CMV infections are usually asymptomatic, however, in immunocompromised individuals and newborns they can lead to severe sequelae and life-threatening conditions. Congenital CMV infection is the most common congenital infection that can affect brain development and cause severe neurological disabilities. CMV can infect a broad range of cells including neurons, which employ pro-survival strategies to avoid destruction from the immune system. Generally, CD4+ and CD8+ T cells play a crucial role in the control of CMV infection in the brain. Since these cells secrete IFNγ, the objective of this thesis is to determine the role of IFNγ in the control of MCMV infection in neurons, using a mouse model of congenital infection. For this purpose, newborn mice lacking IFNγR in neurons were infected with MCMV and organs were harvested at three timepoints of infection. Viral titers in brain were determined by plaque assay and the percentage of infected neurons was quantified by dual immunohistochemical analysis. Analysis of viral titers was also performed for congenitally infected mice lacking IFNγR in astrocytes. The results of these experiments show that IFNγ does not directly control MCMV infection in neurons and astrocytes, both during, and after resolution of productive infection. These findings add to the understanding of immune responses to CMV infection which is pivotal for development of effective therapies and vaccines and raise new questions on which molecules and cells are involved in the control of CMV infection in neurons.Citomegalovirus (CMV) je široko rasprostranjen β-herpesvirus koji inficira većinu populacije širom svijeta. CMV infekcije su obično asimptomatske, međutim u imunokompromitiranih pojedinaca i novorođenčadi mogu dovesti do ozbiljnih posljedica te stanja opasnih po život. Kongenitalna CMV infekcija je najčešća kongenitalna infekcija koja može utjecati na razvoj mozga i uzrokovati ozbiljne neurološke poremećaje. CMV može inficirati širok raspon stanica, uključujući neurone koji koriste strategije preživljavanja kako bi izbjegli uništenje od strane imunološkog sustava. Općenito, CD4+ i CD8+ T stanice imaju presudnu ulogu u kontroli CMV infekcije u mozgu. Budući da te stanice izlučuju IFNγ, cilj ovog rada je utvrditi ulogu IFNγ u kontroli MCMV infekcije u neuronima, koristeći mišji model kongenitalne infekcije. U tu svrhu, novorođeni miševi kojima nedostaje IFNγR u neuronima inficirani su MCMV-om te su im organi prikupljeni u tri vremenske točke infekcije. Virusni titar u mozgu je određen analizom plakova te je kvantificiran postotak inficiranih neurona analizom dvojne imunohistokemije. Analiza virusnih titrova provedena je i za kongenitalno-inficirane miševe kojima nedostaje IFNγR u astrocitima. Rezultati ovih eksperimenata pokazuju da IFNγ nema direktnu kontrolu nad MCMV infekcijom u neuronima i astrocitima tijekom te nakon rezolucije produktivne infekcije. Ovi pronalasci pridodaju razumijevanju imunoloških odgovora na CMV infekciju, što je ključno za razvoj učinkovitih terapija i cjepiva te postavljaju nova pitanja o tome koje molekule i stanice su uključene u kontrolu CMV infekcije u neuronima