Visualization and quantification of simian immunodeficiency virus-infected cells using non-invasive molecular imaging

Abstract

In vivo imaging can provide real-time information and three-dimensional (3D) non-invasive images of deep tissues and organs, including the brain, whilst allowing longitudinal observation of the same animals, thus eliminating potential variation between subjects. Current in vivo imaging technologies, such as magnetic resonance imaging (MRI), positron emission tomography-computed tomography (PET-CT) and bioluminescence imaging (BLI), can be used to pinpoint the spatial location of target cells, which is urgently needed for revealing human immunodeficiency virus (HIV) dissemination in real-time and HIV-1 reservoirs during suppressive antiretroviral therapy (ART). To demonstrate that in vivo imaging can be used to visualize and quantify simian immunodeficiency virus (SIV)-transduced cells, we genetically engineered SIV to carry different imaging reporters. Based on the expression of the reporter genes, we could visualize and quantify the SIV-transduced cells via vesicular stomatitis virus glycoprotein pseudotyping in a mouse model using BLI, PET-CT or MRI. We also engineered a chimeric EcoSIV for in vivo infection study. Our results demonstrated that BLI is sensitive enough to detect as few as five single cells transduced with virus, whilst PET-CT can provide 3D images of the spatial location of as few as 10 000 SIV-infected cells. We also demonstrated that MRI can provide images with high spatial resolution in a 3D anatomical context to distinguish a small population of SIV-transduced cells. The in vivo imaging platform described here can potentially serve as a powerful tool to visualize lentiviral infection, including when and where viraemia rebounds, and how reservoirs are formed and maintained during latency or suppressive ART.

Functional screening of guide RNAs targeting the regulatory and structural HIV-1 viral genome for a cure of AIDS

“…The EcoHIV-eLuc reporter was selected because (1) it contains all the components needed for HIV-1 replication except for the HIV Env, (2) convenient to be handled at biosafety level II containers due to Env deletion and (3) bioluminescence is more sensitive than fluorescence and the eLuc reporter can be used to detect less than 10 single cells[38]. We chose the HEK293T cell line because of the high transfection efficiency with the cost-effective calcium phosphate precipitation method.…”

Whole body MRI of the non-human primate using a clinical 3T scanner: initial experiences

“…It has been explored previously to image immune cell (such as CD4 T+ cells, CD8 T+ cells, and Mac1+ cells) location and homing in the central nervous system of mice with superparamagnetic antibodies (51). Molecular imaging has been successfully applied to visualize simian immunodeficiency virus (SIV)-infected cells in the body of rodent models of HIV (52). Like human, lymph nodes are located throughout the whole body of a macaque monkey.…”

Visualizing the Immune System: Providing Key Insights into HIV/SIV Infections

“…Complementary to these imaging studies, use of laser capture microdissection revealed a compartmentalization of viral sequences in brain from animals infected with a neurotropic virus ( 109 ). In addition to tissue imaging assays, MRI-based methodologies have been widely used for the study of HIV/SIV neuropahtogenesis ( 110 – 113 ) as well as the in vivo viral dynamics in the brain of experimental models ( 17 ).…”

“…Today, several imaging technologies and platforms are available for tissue analysis. Several factors should be taken into consideration regarding the choice of the most relevant platform, including the following: The scientific question under investigation: tissue cell composition and viral reservoirs [light microscopy, confocal microscopy, ion beam imaging ( 126 ), Laser Capture Microdissection ( 127 )], subcellular structure and virus–host protein interactions (confocal microscopy, electron microscopy, high-resolution optical imaging technologies), or assessment of cellular and viral dynamics at organ or whole-body level [MRI ( 17 ), PET scan ( 123 ), confocal endoscopy]. The requirement for high-resolution, “volumetric” analysis or live imaging (two-photon microscopy) to address the biological process under investigation.…”

“…The scientific question under investigation: tissue cell composition and viral reservoirs [light microscopy, confocal microscopy, ion beam imaging ( 126 ), Laser Capture Microdissection ( 127 )], subcellular structure and virus–host protein interactions (confocal microscopy, electron microscopy, high-resolution optical imaging technologies), or assessment of cellular and viral dynamics at organ or whole-body level [MRI ( 17 ), PET scan ( 123 ), confocal endoscopy].…”