Developing and validating SARS-CoV-2 assays for nonhuman primate surveillance.

INTRODUCTION: In early 2020, the California National Primate Research Center implemented surveillance to address the threat of SARS-CoV-2 infection in its nonhuman primate colony. MATERIALS/METHODS: To detect antiviral antibodies, multi-antigen assays were developed and validated on enzyme immunoassay and multiplex microbead immunofluorescent assay (MMIA) platforms. To detect viral RNA, RT-PCR was also performed. RESULTS/CONCLUSION: Using a 4plex, antibody was identified in 16/16 experimentally infected animals; and specificity for spike, nucleocapsid, receptor binding domain, and whole virus antigens was 95.2%, 93.8%, 94.3%, and 97.1%, respectively on surveillance samples. Six laboratories compared this MMIA favorably with nine additional laboratory-developed or commercially available assays. Using a screen and confirm algorithm, 141 of the last 2441 surveillance samples were screen-reactive requiring confirmatory testing. Although 35 samples were reactive to either nucleocapsid or spike; none were reactive to both. Over 20 000 animals have been tested and no spontaneous infections have so far been confirmed across the NIH sponsored National Primate Research Centers.

Tuberculosis detection in nonhuman primates is enhanced by use of testing algorithms that include an interferon-γ release assay.

OBJECTIVE: To develop a testing algorithm that incorporates multiple assays to evaluate host cellular and humoral immunity and antigen detection concerning Mycobacterium tuberculosis complex (MTBC) infection in captive nonhuman primates. ANIMALS: Cohorts of captive-bred and wild-caught macaques from 5 different geographic regions. PROCEDURES: Macaques were tested for MTBC infection by use of a γ interferon tuberculosis (GIFT) assay, an interferon-γ release assay, and other assays. In the first 2 cohorts (n = 15 and 181), initial validation of the GIFT assay was performed by use of experimentally infected and unexposed control macaques. In the next 3 cohorts (n = 59, 42, and 11), results were obtained for opportunistically collected samples from macaques exposed during spontaneous outbreaks. RESULTS: Sensitivity and specificity of the GIFT assay in the control cohorts were 100% and 97%, respectively, and were variable but enhanced by incorporating results from multiple assays in spontaneous outbreaks. CLINICAL RELEVANCE: The detection and management of MTBC infection in captive nonhuman primate populations is an ongoing challenge, especially with animal imports and transfers. Despite standardized practices of initial quarantine with regular intradermal tuberculin skin testing, spontaneous outbreaks continue to be reported. Since infection encompasses a range of disease manifestations over time, a testing algorithm that incorporates multiple assays, such as the GIFT assay, to evaluate host cellular and humoral immunity in addition to agent detection is needed. Testing a combination of samples from controlled studies and spontaneous outbreaks of MTBC infection in nonhuman primates would advance the development and validation of a functional algorithm that incorporates promising tools such as the GIFT assay.

SARS-CoV-2 surveillance for a non-human primate breeding research facility.

BACKGROUND: The emergence of SARS-CoV-2 and the ensuing COVID-19 pandemic prompted the need for a surveillance program to determine the viral status of the California National Primate Research Center non-human primate breeding colony, both for reasons of maintaining colony health and minimizing the risk of interference in COVID-19 and other research studies. METHODS: We collected biological samples from 10% of the rhesus macaque population for systematic testing to detect SARS-CoV-2 virus by RT-PCR and host antibody response by ELISA. Testing required the development and validation of new assays and an algorithm using in laboratory-developed and commercially available reagents and protocols. RESULTS AND CONCLUSIONS: No SARS-CoV-2 RNA or antibody was detected in this study; therefore, we have proposed a modified testing algorithm for sentinel surveillance to monitor for any future transmissions. As additional reagents and controls become available, assay development and validation will continue, leading to the enhanced sensitivity, specificity, accuracy, and efficiency of testing.