An immunoPET probe to SARS-CoV-2 reveals early infection of the male genital tract in rhesus macaques

Abstract

Because of the recognized systemic nature of SARS-CoV-2 infection, a non-invasive and unbiased method is needed to clarify its spatiotemporal dynamics in vivo after transmission. We recently developed a probe based on the anti-SARS-CoV-2 spike antibody CR3022 to study SARS-CoV-2 pathogenesis in vivo. Herein, we describe its use in immunoPET to investigate SARS-CoV-2 infection of rhesus macaques. Using PET/CT imaging of macaques at different times post-SARS-CoV-2 inoculation, we demonstrate that the 64Cu-labelled CR3022-F(ab′)2 probe targeting the spike protein of SARS-CoV-2 can be used to study the dynamics of infection within the respiratory tract and uncover novel sites of infection. Differences in lung pathology between infection with the WA1 isolate and the delta variant were readily observed using immunoPET and corroborated CT lung pathology. The ability of the probe to illuminate lung-associated pathology demonstrates its specificity and function to detect infection in PET scan. The 64Cu-CR3022-probe also demonstrated dynamic changes occurring between 1- and 2-weeks post-infection. Remarkably, a robust signal was seen in the male genital tract (MGT) of all three animals studied. Infection of the MGT was validated by immunofluorescence imaging of infected cells in the testicular and penile tissue and severe pathology was observed in the testes of one animal at 2-weeks post-infection. The results presented here underscore the utility of using immunoPET to study the dynamics of SARS-CoV-2 infection to understand its pathogenicity and discover new anatomical sites of viral replication. We provide direct evidence for SARS-CoV-2 infection of the MGT in rhesus macaques revealing the possible pathologic outcomes of viral replication at these sites.

In vitro evidence against productive SARS-CoV-2 infection of human testicular cells: Bystander effects of infection mediate testicular injury

“…Even in the animal models, subgenomic SARS-CoV-2 RNA was detected only in the intratesticular inoculated hamsters (65). Further, the suggestion that SARS-CoV-2 can infect testes of the rhesus macaques by Madden and colleagues was based on the staining of Spike protein (66) and does not confirm if testis can support active replication of the virus. Therefore, taken together, our data showing the total absence of SARS-CoV-2 virions in the media and no cell death in infected cells, provide direct evidence that SARS-CoV-2 cannot establish productive replication in different testicular cells in vitro.…”

A Positron Emission Tomography Tracer Targeting the S2 Subunit of SARS-CoV-2 in Extrapulmonary Infections

“…A previous study described a 64 Cu-labeled CR3022-F(ab′)2 probe based on the anti-SARS-CoV-2S-protein antibody CR3022 to study the dynamics of infection within the respiratory tract and uncover novel sites of infection in rhesus macaques. 31 A strong signal was observed in extrapulmonary organoids, such as the penis, testes, prostate, and pampiniform plexus. In addition, SARS-CoV-2 virus particles and essential structures have been found in several organs, such as the appendix, eyes, heart, and brain.…”

“…Previous research has shown that a 64 Cu-labeled probe could target spike proteins in the respiratory tract and extrapulmonary organs (penis, prostate, testis, and pampiniform plexus) of SARS-CoV-2-infected rhesus macaques. 31 In the present study, MHV-A59 serves as a surrogate for investigating the ability of the probe to detect the spike protein in extrapulmonary organ infection. Above all, the 64 Cu-labeled probe could be utilized for whole-body imaging.…”

“…There is an urgent need to develop sensitive and effective detection methods for SARS-CoV-2 and its variants in extrapulmonary tissues. One promising method of detecting the spatiotemporal distribution of SARS-CoV-2 infection is noninvasion PET/CT agents targeting the S-protein of SARS-CoV-2 . EK1, a peptide-based pan-coronavirus fusion inhibitor, has been shown in previous studies to reduce SARS-CoV-2 infection significantly by specifically targeting the spike protein. , In this study, we reported that the [ 64 Cu]­Cu-NOTA-EK1 tracer that targets the SARS-CoV-2 S-protein’s conserved S2 subunit, constructed the PsV of the SARS-CoV-2 omicron strain to infect HEK293/ACE2 cells in vivo , and mimic the process of extrapulmonary infection in C57BL/6 J mice by MHV-A59, a kind of coronavirus where the S2 subunit is very conserved and is highly homologous to SARS-CoV-2 .…”

“…Animal models are essential to carrying out these experiments because they can provide reliable and detailed tissue information that is otherwise difficult or impossible to obtain in humans. A previous study described a 64 Cu-labeled CR3022-F­(ab′)­2 probe based on the anti-SARS-CoV-2S-protein antibody CR3022 to study the dynamics of infection within the respiratory tract and uncover novel sites of infection in rhesus macaques . A strong signal was observed in extrapulmonary organoids, such as the penis, testes, prostate, and pampiniform plexus.…”