ARBOspot: Characterization of Arbovirus Specific T Cell Response in Patients by Using Enzyme Linked Immunospot (ELISpot) Assays

Arboviruses (arthropod-borne viruses), are a group of RNA viruses that are transmitted to vertebrate hosts by hematophagous arthropods like mosquitos, ticks, and sandflies. In Italy, arboviruses pose a considerable public health concern because of their potential to infect humans and cause severe emergent or re-emergent diseases. Over the past few decades, arboviruses have already been responsible for epidemic outbreaks in Italy, and travels increase the risk of introducing new species previously confined to tropical and sub-tropical regions. Some arboviral infections, like West Nile Virus (WNV), Toscana Virus (TOSV), Sandfly Fever Sicily Virus (SFSV), Sandfly Fever Naples Virus (SFNV), Usutu Virus (USUV), and tick-borne encephalitis virus (TBEV), are considered endemic in Italy. Others, such as Chikungunya Virus (CHIKV), Dengue Virus (DENV), Zika Virus (ZIKV), Yellow Fever Virus (YFV) and Japanese encephalitis Virus (JEV) are under surveillance since imported infections could lead to local outbreaks and subsequent endemic circulation in Italy. Moreover, the increased global travel and unpredictable climate changes could facilitate the spread of arboviral infections. Adequate diagnostic tests play a crucial role in disease surveillance, identifying potential associations between previous infections and chronic diseases and controlling outbreaks by breaking transmission chains. Furthermore, immunological tests can help predict disease severity in healthy and immunocompromised subjects and identify patients at risk for severe disease during secondary infections.

In parallel with direct molecular diagnosis tests, the development of an immunological test capable of determining specific arbovirus T cell response may be useful for diagnostic as well as for epidemiological and investigative purposes. Furthermore, its development provides a set of initial knowledge on which to base the construction of other immunological tests for future emerging viruses, providing tools to counter new epidemic outbreaks. At the same time, the evaluation of immune response is necessary in order to control and contain the spread of these viruses. In conclusion, the present study aims to investigate immunological responses in patients infected with endemic arboviruses circulating in Italy those that could potentially emerging in the future.

Molecular tests have a reduced detectability window in biological samples, which is why often they are not useful for making a diagnosis. Serological tests can give cross-reactivity phenomena between some arboviruses, making differential diagnosis difficult and often inconclusive. Objective is to assess sensitivity of immunological assays for arboviruses-specific T Cell Response (ARBOspot) in order to use them in combination with conventional diagnostic methods.