Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a public health crisis over the last two years. Monoclonal antibody (mAb)-based therapeutics against the spike (S) protein have been shown to be effective treatments for SARS-CoV-2 infection, especially the original viral strain. However, the current mAbs produced in mammalian cells are expensive and might be unaffordable for many. Furthermore, the emergence of variants of concern demands the development of strategies to prevent mutant escape from mAb treatment. Using a cocktail of mAbs that bind to complementary neutralizing epitopes is one such strategy. In this study, we use Nicotiana benthamiana plants in an effort to expedite the development of efficacious and affordable antibody cocktails against SARS-CoV-2. We show that two mAbs can be highly expressed in plants and are correctly assembled into IgG molecules. Moreover, they retain target epitope recognition and, more importantly, neutralize multiple SARS-CoV-2 variants. We also show that one plant-made mAb has neutralizing synergy with other mAbs that we developed in hybridomas. This is the first report of a plant-made mAb to be assessed as a potential component of a SARS-CoV-2 neutralizing cocktail. This work may offer a strategy for using plants to quickly develop mAb cocktail-based therapeutics against emerging viral diseases with high efficacy and low costs.
In a Clinical Laboratory Improvement Amendments laboratory setting, we evaluated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG detection with 4 lateral flow immunoassays [LFIAs; 2 iterations from BTNX Inc. ( n = 457) and 1 each from ACON Laboratories ( n = 200) and SD BIOSENSOR ( n = 155)]. In a cohort of primarily hospitalized, reverse-transcription polymerase chain reaction–confirmed coronavirus disease 2019 cases, sensitivity at ≥14 days from symptom onset was: BTNX kit 1, 95%; BTNX kit 2, 91%; ACON, 95%; and SD, 92%. All assays showed good concordance with the Abbott SARS-CoV-2 IgG assay at ≥14 days from symptom onset: BTNX kit 1, 99%; BTNX kit 2, 94%; ACON, 99%; and SD, 100%. Specificity, measured using specimens collected prior to SARS-CoV-2 circulation in the United States and “cross-reactivity challenge” specimens, was 98% for BTNX kit 1 and ACON and 100% for BTNX kit 2 and SD. These results suggest that LFIAs may provide adequate results for rapid detection of SARS-CoV-2.
Monoclonal antibodies (mAbs) are important proteins used in many life science applications, from diagnostics to therapeutics. High demand for mAbs for different applications urges the development of rapid and reliable recombinant production platforms. Plants provide a quick and inexpensive system for producing recombinant mAbs. Moreover, when paired with an established platform for mAb discovery, plants can easily be tailored to produce mAbs of different isotypes against the same target. Here, we demonstrate that a hybridoma-generated mouse mAb against chitinase 1 (CTS1), an antigen from Coccidioides spp., can be biologically engineered for use with serologic diagnostic test kits for coccidioidomycosis (Valley Fever) using plant expression. The original mouse IgG was modified and recombinantly produced in glycoengineered Nicotiana benthamiana plants via transient expression as IgG and IgM isotypes with human kappa, gamma, and mu constant regions. The two mAb isotypes produced in plants were shown to maintain target antigen recognition to CTS1 using similar reagents as the Food and Drug Administration (FDA)-approved Valley Fever diagnostic kits. As none of the currently approved kits provide antibody dilution controls, humanization of antibodies that bind to CTS1, a major component of the diagnostic antigen preparation, may provide a solution to the lack of consistently reactive antibody controls for Valley Fever diagnosis. Furthermore, our work provides a foundation for reproducible and consistent production of recombinant mAbs engineered to have a specific isotype for use in diagnostic assays.
The first influenza pandemic in more than 40 years was declared in 2009. We aimed to evaluate the beliefs of Spanish infectious diseases professionals regarding several aspects of 2009 A (H1N1) influenza once the epidemic waned. An online survey was designed and distributed among members of the Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC). The survey considered hospital organization and preparedness planning and conduct, as well as the opinion of the infectious diseases professionals regarding several key issues. Between 7 March and 22 March 2010, 303 responses, corresponding to 12.8% of the SEIMC membership, were received. Of the respondents, 48.2% were microbiologists and 42.3% were clinicians dealing with infectious diseases. Forty-one per cent of respondents did not believe that 2009 A (H1N1) influenza had a more severe presentation than other seasonal influenzas. Only 5% fully agreed that 2009 A (H1N1) influenza had a more severe presentation. Influenza planning was available in 69.7% of represented institutions before the arrival of 2009 A (H1N1) influenza, and was considered to be useful, to different extents, by most professionals. In most institutions (88.3%), a multidisciplinary team was created to coordinate local pandemic influenza actions. The most successful protocols were those provided by regional healthcare authorities, followed by those from the CDC. The most problematic issues regarding 2009 A (H1N1) influenza were the management of patients in the emergency room and the vaccination and awareness of healthcare professionals (HCPs) regarding infection control. Microbiological diagnosis and the availability of antivirals were the least problematic areas. Although the majority of surveyed infectious diseases professionals did not believe that 2009 A (H1N1) influenza had an especially severe presentation, most of them agreed with the way that this epidemic was managed in their institutions.
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