C Figures 1 and ?and22. All tissue models can be divided into three types with ten subtypes: 2D models (monolayer culture of cell lines and main cells), 2.5D models (suspension culture using microcarriers and simple air-liquid biointerfaces), and 3D models (explants, organoids/spheroids, embedded cells, cell-seeded scaffolds, bioprinted constructs, and combined systems [organ-on-a chip]). Monolayer (2D) cultures are the oldest and the most widely used model. Cell lines are usually applied to isolate viruses, develop new serological assays, and produce diagnostic reagents or vaccines. The current gold-standard cell collection is usually Vero, an interferon-deficient aneuploid line of kidney epithelial cells[37,38]. A549 and MadinCDarby canine kidney cell lines are mostly applied for influenza viruses[39].The most common cell line for the foot-and-mouth disease virus is the mammalian baby hamster kidney cells[40] which have been used since 1964[41]. Compared to cell lines, main cell cultures have some advantages. For instance, cells isolated from ovine pulmonary adenocarcinoma are a unique platform to reveal mechanisms of epithelial transformation in a case of the lung malignancy caused by the retrovirus contamination[42]. Despite of the availability of cell variety and easy handling and scaling, 2D cultures are not capable of recapitulating fully cell-cell and cell-matrix interactions. Suspension culture is also the oldest model for viral infections and very common for the industrial production of diagnostic reagents, vaccines, etc., due to a simple scaling process[40] V. However, it was significantly improved by adding microcarriers C small particles of a cell adhesive substrate (e.g., Cytodex 3). Such method modification was approved for the production of a RSV vaccine[43] and research on virus-host interactions[44]. Compared to 2D ones, 3D models are highly attractive because they are more relevant to the conditions (Physique 2). Such models can be fabricated through numerous approaches and were approved for different viruses (Table 1). The most common technique to form 3D tissue models is usually cell or spheroid/organoid encapsulation (embedding). Open in a separate window Physique 2 Viral contamination: 2D versus 3D tissue models. Table 1 3D tissue models used to study numerous viral infections. for cells. Biomaterials that make sure necessary cell-matrix interactions and appropriate spatiotemporal surrounding cells are used to form a structure of such models. It was shown that they could make sure physiologically relevant cell responses to computer virus contamination and drugs[39,51]. For instance, Bhowmick conditions. Organ-on-a-chip systems consisting of numerous cell types, perfusion chambers, air-liquid interfaces, etc., mimic and create physiological conditions relevant to viral contamination of UR 1102 native tissues. Microfluidic-based tissue models have many advantages. Particularly, Rabbit Polyclonal to DDX55 microfluidics enables liquid handling at a microscale through a system of microchannels; therefore, the total consumption of reagents is usually relatively low that makes high-throughput screening less difficult and cheaper[56]. Such models are flexible to be automated[57,58], providing the possibility for real-time monitoring[59,60]. Moreover, they allow culturing cells in physiologically relevant dynamic conditions and controlling them[61]. Particularly, such system was tested to study the mechanism of the fusion of UR 1102 feline coronavirus with host cell membrane[62]. 3 In vitro tissue models for modeling an infection caused by different viruses 3.1 Respiratory viruses Tissue models that are used to study respiratory viral infections vary and include both monolayer cultures and functional airway organoids, enabling to obtain reliable data on computer virus infectivity, targets, and drug efficacy. Coronaviruses, a group of respiratory viruses, mostly infect epithelial cells that are used in designing relevant 3D models. The recent studies are based on organoids as a tissue model. For instance, Monteil models to study hepatotropic viruses[63]. 3.3 Herpesviruses Epithelial tissue is the initial site of infection for most herpesviruses. Although they cause latent contamination mainly in neurons, they are still able to infect other cells. Therefore, there are numerous tissue models available, which include numerous cell types to study this computer virus group. For example, Tajpara conditions, including 3D environment, flows dynamics, and immune response. Moreover, blood vessel and human kidney organoids are still the only 3D models used to study SARS-CoV-2 contamination[8]. 4.2 Specific targets Despite SARS-CoV-2 is a novel virus infecting humans, understanding of its possible entry mechanisms was already pre-defined because of earlier studies on other coronaviruses, for example, SARS-CoV[82-85]. Therefore, after its appearance, most research teams have been focusing on UR 1102 SARS-CoV receptor ACE2 and other related enzymes. Particularly, Hoffmann platforms that mimic conditions and are specifically tailored for the SARS-CoV-2 contamination. There is no doubt that 3D tissue models are more suitable than 2D models to study any viral infections because they share the similarity to the native tissue, organ structure, and physiological functionality, and this is also relevant to COVID-19. 3D tissue-like constructs can be fabricated by a huge variety of methods that can be divided into two main groups: Scaffold-based and scaffold-free. However,.