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Background: Several studies have associated members of the KIR genes as susceptibility factors to inflammatory bowel diseases (IBD): ulcerative colitis (UC) and Crohn's disease (CD). Objectives: To assess the association between the presence and absence KIR genes and IBD susceptibility through a meta-analysis. Method: A systematic search was performed through the PubMed, Scopus, and Web of Science databases to obtain relevant articles published before March 2024. Associations between genes and susceptibility to IBDs were estimated by OR with 95 % CI. Results: We found positive associations of the KIR2DS1 and KIR2DS3 genes with susceptibility to UC, while the KIR2DL3 and KIR2DS4 full genes showed a negative association. In addition, the KIR2DS1, KIR2DS3, KIR2DS4, KIR2DS5, and KIR3DS1 genes showed a positive association with susceptibility to CD, whereas the KIR2DL1 gene showed a negative association. Conclusions: Our meta-analysis indicates that individuals carrying the KIR2DS1 and KIR2DS3 genes exhibit increased susceptibility to UC, whereas carriers of the KIR2DS1, KIR2DS3, KIR2DS4, KIR2DS5, and KIR3DS1 genes are more prone to CD. However, further studies are required to clarify the role of the KIR genes and their corresponding ligands in the pathology of IBD.
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Bacterial symbionts in insects constitute a key factor for the survival of the host due to the benefits they provide. Parasitoid wasps are closely associated with viruses, bacteria, and fungi. However, the primary symbionts and their functions are not yet known. This study was undertaken to determine the gut microbiota of six species of the Telenomus genus: T. alecto (Crawford), T. sulculus Johnson, T. fariai Costa Lima, T. remus Nixon, T. podisi Ashmead, and T. lobatus Johnson & Bin. Wasp parasitoids were collected from their hosts in different locations in Mexico. DNA was extracted from gut collection, and sequencing of bacterial 16S rRNA was carried out in Illumina® MiSeq™. Among the six species of wasps, results showed that the most abundant phylum were Proteobacteria (82.3%), Actinobacteria (8.1%), and Firmicutes (7.8%). The most important genera were Delftia and Enterobacter. Seventeen bacteria species were found to be shared among the six species of wasps. The associate microbiota will help to understand the physiology of Telenomus to promote the use of these wasp parasitoids in the management of insect pests and as potential biomarkers to target new strategies to control pests.
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Between 2 and 8.5% of patients who recover from COVID-19 do not develop antibodies, and the durability of IgG antibodies is under scrutiny. Therefore, the presence and persistence of IgM and IgG antibodies were evaluated in a group of patients diagnosed with SARS-CoV-2 from May to August 2020. Out of 2199 suspected COVID-19 cases, 1264 were confirmed for SARS-CoV-2 by rRT-PCR; 328 consented to participate in the study, with 220 participants followed for 9 months, including 124 men (56%) and 96 women (44%). The primary symptoms were headache, dry cough, and fever. IgG antibodies developed in 95% of patients within 4 weeks post-diagnosis, and a second evaluation at 9 months showed that 72.7% still had detectable IgG antibodies. The presence of IgM in one individual (0.45%) suggested the possibility of reinfection.
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COVID-19 made explicit the need for rethinking the way in which we conduct testing for epidemic emergencies. During the COVID-19 pandemic, the dependence on centralized lab facilities and resource-intensive methodologies (e.g., RT-qPCR methods) greatly limited the deployment of widespread testing efforts in many developed and underdeveloped countries. Here, we illustrate the development of a simple and portable diagnostic kit that enables self-diagnosis of COVID-19 at home from saliva samples. We describe the development of a do-it-yourself (DIY) incubator for Eppendorf tubes that can be used to conduct SARS-CoV-2 detection with competitive sensitivity and selectivity from saliva at home. In a proof-of-concept experiment, we assembled Eppendorf-tube incubators at our home shop, prepared a single-tube mix of reagents and LAMP primers in our lab, and deployed these COVID-19 detection kits using urban delivery systems (i.e., Rappifavor or Uber) to more than 15 different locations in Monterrey, México. This straightforward strategy enabled rapid and cost-effective at-home molecular diagnostics of SARS-CoV-2 from real saliva samples with a high sensitivity (100%) and high selectivity (87%).
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Pre-eclampsia (PE) is a disorder characterized by hypertension in the second trimester of pregnancy that results from abnormal placentation affecting fetal development and maternal health. Previous studies have shown the role of serotonin (5-HT) that leads to poor placental perfusion, where S/S and S/L polymorphisms promote the solute carrier family 6 member 4 (SLC6A4) gene associated with the risk of developing changes in the microvasculature of the placenta. This study looked at the association between the gene variant 5-HTTLPR (serotonin-transporter-linked promoter region) of the SLC6A4 gene and the occurrence of PE. A total of 200 women were included: 100 cases (pregnant with PE) and 100 controls (pregnant without complications). Genotyping of the 5-HTTLPR variant was performed using polymerase chain reaction (PCR). Associations between the presence of the genetic variant of interest and PE and other clinical features were evaluated statistically. The frequencies of S/S, S/L, and L/L genotypes were 32%, 53%, and 15% for the cases and 55%, 25%, and 20% in the control group. Compared to the controls, the genotype frequencies S/S vs. S/L + L/L (recessive model) in the cases group were different (p = 0.002). The S/S genotype decreased the probability of PE (OR = 0.39, 95% IC: 0.22-0.69, p = 0.002) and PE with severity criteria (OR = 0.39, 95% IC: 0.17-0.91, p = 0.045). The 5-HTTLPR gene variant of the SLC6A4 gene modifies the risk of PE development among the studied population.
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The global spread of antimicrobial resistance genes (ARGs) is a major public health concern. Mobile genetic elements (MGEs) are the main drivers of this spread by horizontal gene transfer (HGT). Escherichia coli is widespread in various environments and serves as an indicator for monitoring antimicrobial resistance (AMR). Therefore, the objective of this work was to evaluate the whole genome of multidrug-resistant E. coli strains isolated from human clinical, animal, and environmental sources. Four E. coli strains previously isolated from human urine (n = 2), retail meat (n = 1), and water from the Rio Grande River (n = 1) collected in northern Tamaulipas, Mexico, were analyzed. E. coli strains were evaluated for antimicrobial susceptibility, followed by whole genome sequencing and bioinformatic analysis. Several ARGs were detected, including blaCTX-M-15, blaOXA-1, blaTEM-1B, blaCMY-2, qnrB, catB3, sul2, and sul3. Additionally, plasmid replicons (IncFIA, IncFIB, IncFII, IncY, IncR, and Col) and intact prophages were also found. Insertion sequences (ISs) were structurally linked with resistance and virulence genes. Finally, these findings indicate that E. coli strains have a large repertoire of resistance determinants, highlighting a high pathogenic potential and the need to monitor them.
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PURPOSE: This study aims to develop and evaluate a cost-effective, user-friendly multiplex quantitative real-time polymerase chain reaction (qPCR) method for detecting multiple tick-borne pathogens associated with human and veterinary diseases. METHODS: In silico PCR was performed to design and evaluate primer sequences reported for amplifying Rickettsia spp., Borrelia spp., and Ehrlichia spp. Single and multiplex qPCR assays were then standardized to detect individual pathogens and multiple pathogens in a single reaction. Positive controls were generated to determine the dynamic range of the methods. In the validation phase, a total of 800 samples were screened for the presence of tick-borne pathogens. RESULTS: Identification in a single qPCR reaction (multiplex) of Ehrlichia spp., and Borrelia spp. with a limit of detection of 10 copies and Rickettsia spp. with 100 copies, a PCR efficiency (E) of 90-100% and a coefficient of correlation (R2) of 0.998-0.996 for all pathogens. CONCLUSION: The ability to detect three significant pathogens (Ehrlichia spp., Rickettsia spp., and Borrelia spp.) in a single qPCR reaction offers a significant advantage in the field of molecular diagnostics for tick-borne diseases. This advancement has a profound impact on public health as it facilitates the selection of appropriate treatment protocols, thereby reducing complications associated with disease progression. The streamlined approach provided by this method simplifies the diagnostic process and enables timely intervention, ultimately improving patient outcomes and mitigating the potential risks associated with untreated or misdiagnosed tick-borne infections.
Subject(s)
Borrelia , Rickettsia , Tick-Borne Diseases , Ticks , Animals , Humans , Ticks/microbiology , Real-Time Polymerase Chain Reaction , Rickettsia/genetics , Ehrlichia/genetics , Tick-Borne Diseases/diagnosis , Tick-Borne Diseases/veterinary , Borrelia/geneticsABSTRACT
The growth hormone (GH) locus has experienced a dramatic evolution in primates, becoming multigenic and diverse in anthropoids. Despite sequence information from a vast number of primate species, it has remained unclear how the multigene family was favored. We compared the structure and composition of apes' GH loci as a prerequisite to understanding their origin and possible evolutionary role. These thorough analyses of the GH loci of the chimpanzee, gorilla, and orangutan were done by resorting to previously sequenced bacterial artificial chromosomes (BACs) harboring them, as well as to their respective genome projects data available in GenBank. The GH loci of modern man, Neanderthal, gibbon, and wild boar were retrieved from GenBank. Coding regions, regulatory elements, and repetitive sequences were identified and compared among species. The GH loci of all the analyzed species are flanked by the genes CD79B (5') and ICAM-1 (3'). In man, Neanderthal, and chimpanzee, the loci were integrated by five almost indistinguishable genes; however, in the former two, they rendered three different hormones, and in the latter, four different proteins were derived. Gorilla exhibited six genes, gibbon seven, and orangutan four. The sequences of the proximal promoters, enhancers, P-elements, and a locus control region (LCR) were highly conserved. The locus evolution might have implicated duplications of the ancestral pituitary gene (GH-N) and subsequent diversification of the copies, leading to the placental single GH-V gene and the multiple CSH genes.
Subject(s)
Hominidae , Human Growth Hormone , Neanderthals , Animals , Female , Pregnancy , Hominidae/genetics , Pan troglodytes/genetics , Gorilla gorilla/genetics , Hylobates/genetics , Neanderthals/genetics , Base Sequence , Phylogeny , Placenta , Growth Hormone , Human Growth Hormone/genetics , Primates/genetics , Pongo/geneticsABSTRACT
The abnormal implantation of the trophoblast during the first trimester of pregnancy precedes the appearance of the clinical manifestations of preeclampsia (PE), which is a hypertensive disorder of pregnancy. In a previous study, which was carried out in a murine model of PE that was induced by NG-nitro-L-arginine methyl ester (L-NAME), we observed that the intravenous administration of fibroblast growth factor 2 (FGF2) had a hypotensive effect, improved the placental weight gain and attenuated the fetal growth restriction, and the morphological findings that were induced by L-NAME in the evaluated tissues were less severe. In this study, we aimed to determine the effect of FGF2 administration on the placental gene expression of the vascular endothelial growth factor (VEGFA), VEGF receptor 2 (VEGFR2), placental growth factor, endoglin (ENG), superoxide dismutase 1 (SOD1), catalase (CAT), thioredoxin (TXN), tumor protein P53 (P53), BCL2 apoptosis regulator, Fas cell surface death receptor (FAS), and caspase 3, in a Sprague Dawley rat PE model, which was induced by L-NAME. The gene expression was determined by a real-time polymerase chain reaction using SYBR green. Taking the vehicle or the L-NAME group as a reference, there was an under expression of placental VEGFA, VEGFR2, ENG, P53, FAS, SOD1, CAT, and TXN genes in the group of L-NAME + FGF2 (p < 0.05). The administration of FGF2 in the murine PE-like model that was induced by L-NAME reduced the effects that were generated by proteinuria and the increased BP, as well as the response of the expression of genes that participate in angiogenesis, apoptosis, and OS. These results have generated valuable information regarding the identification of molecular targets for PE and provide new insights for understanding PE pathogenesis.
Subject(s)
Fibroblast Growth Factor 2 , Pre-Eclampsia , Animals , Disease Models, Animal , Female , Fibroblast Growth Factor 2/pharmacology , Gene Expression , Humans , NG-Nitroarginine Methyl Ester/adverse effects , Placenta/metabolism , Placenta Growth Factor/genetics , Placenta Growth Factor/metabolism , Pre-Eclampsia/chemically induced , Pre-Eclampsia/drug therapy , Pre-Eclampsia/genetics , Pregnancy , Rats , Rats, Sprague-Dawley , Superoxide Dismutase-1/genetics , Tumor Suppressor Protein p53/metabolism , Vascular Endothelial Growth Factor A/metabolismABSTRACT
Prolactin (PRL) is a hormone expressed in lactotrophs cells of the pituitary gland in primates. Extra pituitary expression of PRL has been reported, including the eye; however, expression in the developing eye of primates is limited. The aim of the study was determining the expression of PRL and PRL receptor (PRLR) (mRNAs and proteins) in adult and fetal baboon (Papio hamadryas) ocular tissues. METHODS: We analyzed PRL and PRLR in baboon eyes tissues by immunofluorescence. The mRNAs of PRL and PRLR were detected by RT-PCR, cDNA was cloned, and sequenced. Furthermore, we performed a phylogenetic analysis to identify the evolutionary forces that underlie the divergence of PRL and PRLR primate genes. RESULTS: We observed the expression of PRL and PRLR (mRNAs and proteins) in all retinal cell lineages of fetal and adult baboon. PRL and PRLR fit the hypothesis of evolutionary purifying gene selection. CONCLUSIONS: mRNA and protein of PRL and PRLR are expressed in fetal and adult baboon retinal tissue. PRL may trigger autocrine and paracrine-specific actions in retinal cell lines.
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Autism spectrum disorders (ASDs) are a group of neurodevelopmental pathologies characterized by social and communication deficits, for which treatments are limited. Cell therapies, including intrathecal (IT) administration of bone marrow (BM) mononuclear cells (BM-MNC), improves symptoms in patients with ASD. Twenty-four patients diagnosed with ASD, according to the Diagnostic and Statistical Manual of Mental Disorders Text Revision Fourth Edition (DSM-IV-TR) criteria, were autologously treated with IT BM-MNC, and the clinical effect was evaluated using the Childhood Autism Rating Scale (CARS) on Days 30 (n=24) and 180 (n=14) post-treatment. IT BM-MNC improved clinical outcomes by Day 30 (p=0.0039), and those benefits remained and were further accentuated by Day 180 post-treatment (n=14; p=<0.0001). Clinical benefit at Days 30 (p=0.001; r= -0.51) and 180 (p=0.01; r= -0.60) posttreatment positively correlated with the enrichment of a putative BM stem cell population expressing the cluster of differentiation 133+ (CD133+) surface marker.
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Background: The pandemic of COVID-19 has represented a major threat to global public health in the last century and therefore to identify predictors of mortality among COVID-19 hospitalized patients is widely justified. The aim of this study was to evaluate the possible usefulness of Charlson Comorbidity Index (CCI) as mortality predictor in patients hospitalized because COVID-19. Methods: This study was carried out in Zacatecas, Mexico, and it included 705 hospitalized patients with suspected of SARS-CoV-2 infection. Clinical data were collected, and the CCI score was calculated online using the calculator from the Sociedad Andaluza de Medicina Intensiva y Unidades Coronarias; the result was evaluated as mortality predictor among the patients with COVID-19. Results: 377 patients were positive for SARS-COV-2. Obesity increased the risk of intubation among the study population (odds ratio (OR) = 2.59; 95 CI: 1.36-4.92; p = 0.003). The CCI values were higher in patients who died because of COVID-19 complications than those observed in patients who survived (p < 0.001). Considering a CCI cutoff > 31.69, the area under the ROC curve was 0.75, with a sensitivity and a specificity of 63.6% and 87.7%, respectively. Having a CCI value > 31.69 increased the odds of death by 12.5 times among the study population (95% CI: 7.3-21.4; p < 0.001). Conclusions: The CCI is a suitable tool for the prediction of mortality in patients hospitalized for COVID-19. The presence of comorbidities in hospitalized patients with COVID-19 reflected as CCI > 31.69 increased the risk of death among the study population, so it is important to take precautionary measures in patients due to their condition and their increased vulnerability to SARS-CoV-2 infection.
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INTRODUCTION: Coronavirus disease 19 (COVID-19) has been a global public health emergency, with 209.89 million cases of infection with SARS-CoV-2 recorded, resulting in 4,401,675 deaths. After recuperation, it is probable that COVID-19 patients have sequelae of the disease. This study aimed to evaluate the respiratory anatomical-functional sequelae in Mexican patients who recovered from COVID-19. METHODOLOGY: This study included twenty-four patients who recovered from COVID-19 and eight non-infected patients (controls). Participants were screened for SARS-CoV-2 and the presence of IgM/IgG antibodies. Pulmonary function and lung anatomical abnormalities were evaluated by spirometry and computerized tomography. RESULTS: A total of 45.8% of the patients had pulmonary function with obstructive patterns: 70.8% of recovered cases had COVID-19 Reporting and Data System (CO-RADS) 1, 20.8% CO-RADS 3 and 16.7% CO-RADS 4. A total of 35.3% of patients with CO-RADS 1 also showed bilateral nodal growth; 70.8% of patients tested positive for IgG and 8.4% for IgG/IgM, and 20.8% tested negative for both antibodies. CONCLUSIONS: There were respiratory anatomical and functional sequelae in Mexican patients who recovered from COVID-19, with a high occurrence of pulmonary obstructive patterns in the study population. These observations indicate the importance of the routine evaluation of sequelae in Mexican patients who recovered from COVID-19 and the need for strict follow-up to improve the quality of life of these patients.
Subject(s)
COVID-19 , Antibodies, Viral , Humans , Immunoglobulin M , Lung , Quality of Life , SARS-CoV-2ABSTRACT
Emerging and re-emerging vector-borne infections are a global public health threat. In endemic regions, fever is the main reason for medical attention, and the etiological agent of such fever is not usually identified. In this study, non-specific febrile pathogens were molecularly characterized in serum samples from 253 patients suspected of arbovirus infection. The samples were collected in the southern border region of Mexico from April to June 2015, and February to March 2016. ZIKV, CHIKV, DENV, leptospirosis, and rickettsiosis were detected by qPCR and nested PCR to identify flavivirus and alphavirus genera. The results indicated that 71.93% of the samples were positive for CHIKV, 0.79% for ZIKV, and 0.39% for DENV, with the number positive for CHIKV increasing to 76.67% and those positive for ZIKV increasing to 15.41% under the nested PCR technique. Leptospira Kmetyi was identified for the first time in Mexico, with a prevalence of 3.16%. This is the first report of ZIKV in Mexico, as well the first detection of the virus in early 2015. In conclusion, the etiological agent of fever was determined in 94% of the analyzed samples.
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The COVID-19 pandemic has been the most critical public health issue in modern history due to its highly infectious and deathly potential, and the limited access to massive, low-cost, and reliable testing has significantly worsened the crisis. The recovery and the vaccination of millions of people against COVID-19 have made serological tests highly relevant to identify the presence and levels of SARS-CoV-2 antibodies. Due to its advantages, microfluidic-based technologies represent an attractive alternative to the conventional testing methodologies used for these purposes. In this work, we described the development of an automated ELISA on-chip capable of detecting anti-SARS-CoV-2 antibodies in serum samples from COVID-19 patients and vaccinated individuals. The colorimetric reactions were analyzed with a microplate reader. No statistically significant differences were observed when comparing the results of our automated ELISA on-chip against the ones obtained from a traditional ELISA on a microplate. Moreover, we demonstrated that it is possible to carry out the analysis of the colorimetric reaction by performing basic image analysis of photos taken with a smartphone, which constitutes a useful alternative when lacking specialized equipment or a laboratory setting. Our automated ELISA on-chip has the potential to be used in a clinical setting and mitigates some of the burden caused by testing deficiencies.
Subject(s)
COVID-19 , SARS-CoV-2 , Antibodies, Viral , Enzyme-Linked Immunosorbent Assay , Humans , Pandemics , Sensitivity and SpecificityABSTRACT
Iron and copper chelation restricts Plasmodium growth in vitro and in mammalian hosts. The parasite alters metal homeostasis in red blood cells to its favor, for example metabolizing hemoglobin to hemozoin. Metal interactions with the mosquito have not, however, been studied. Here, we describe the metallomes of Anopheles albimanus and Aedes aegypti throughout their life cycle and following a blood meal. Consistent with previous reports, we found evidence of maternal iron deposition in embryos of Ae. aegypti, but less so in An. albimanus. Sodium, potassium, iron, and copper are present at higher concentrations during larval developmental stages. Two An. albimanus phenotypes that differ in their susceptibility to Plasmodium berghei infection were studied. The susceptible white stripe (ws) phenotype was named after a dorsal white stripe apparent during larval stages 3, 4, and pupae. During larval stage 3, ws larvae accumulate more iron and copper than the resistant brown stripe (bs) phenotype counterparts. A similar increase in copper and iron accumulation was also observed in the susceptible ws, but not in the resistant bs phenotype following P. berghei infection. Feeding ws mosquitoes with extracellular iron and copper chelators before and after receiving Plasmodium-infected blood protected from infection and simultaneously affected follicular development in the case of iron chelation. Unexpectedly, the application of the iron chelator to the bs strain reverted resistance to infection. Besides a drop in iron, iron-chelated bs mosquitoes experienced a concomitant loss of copper. Thus, the effect of metal chelation on P. berghei infectivity was strain-specific.
Subject(s)
Anopheles/metabolism , Anopheles/parasitology , Copper/metabolism , Iron/metabolism , Animals , Anopheles/growth & development , Blood/metabolism , Chelating Agents/pharmacology , Female , Host-Parasite Interactions , Malaria/physiopathology , Male , Phenanthrolines/pharmacology , Plasmodium berghei/physiologyABSTRACT
Background: In preeclampsia, a hypertensive disorder of pregnancy, the poor remodeling of spiral arteries leads to placental hypoperfusion and ischemia, provoking generalized maternal endothelial dysfunction and, in severe cases, death. Endothelial and placental remodeling is important for correct pregnancy evolution and is mediated by cytokines and growth factors such as fibroblast growth factor type 2 (FGF2). In this study, we evaluated the effect of human recombinant FGF2 (rhFGF2) administration in a murine model of PE induced by NG-nitro-L-arginine methyl ester (L-NAME) to test if rhFGF2 administration can lessen the clinical manifestations of PE. Methods: Pregnant rats were administrated with 0.9% of NaCl (vehicle), L-NAME (60 mg/kg), FGF2 (666.6 ng/kg), L-NAME+FGF2 or L-NAME + hydralazine (10 mg/kg) from the 10th to 19th days of gestation. Blood pressure (BP), urine protein concentrations and anthropometric values both rat and fetuses were assessed. Histological evaluation of organs from rats delivered by cesarean section was carried out using hematoxylin and eosin staining. Results: A PE-like model was established, and it included phenotypes such as maternal hypertension, proteinuria, and fetal growth delay. Compared to the groups treated with L-NAME, the L-NAME + FGF2 group was similar to vehicle: the BP remained stable and the rats did not develop enhanced proteinuria. Both the fetuses and placentas from rats treated with L-NAME + FGF2 had similar values of weight and size compared with the vehicle. Conclusion: The intravenous administration of rhFGF2 showed beneficial and hypotensive effects, reducing the clinical manifestations of PE in the evaluated model.
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Aedes aegypti L. is the most important vector of arboviruses such as dengue, Zika, chikungunya, Mayaro, and yellow fever, which impact millions of people's health per year. MicroRNA profile has been described in some mosquito species as being important for biological processes such as digestion of blood, oviposition, sexual differentiation, insecticide resistance, and pathogens dissemination. We identified the miRNAs of Ae. aegypti females, males and eggs of a reference insecticide susceptible strain New Orleans and compared them with those other insects to determine miRNA fingerprint by new-generation sequencing. The sequences were analyzed using data mining tools and categorization, followed by differential expression analysis and conservation with other insects. A total of 55 conserved miRNAs were identified, of which 34 were of holometabolous insects and 21 shared with hemimetabolous insects. Of these miRNAs, 32 had differential expression within the stages analyzed. Three predominant functions of miRNA were related to embryonic development regulation, metamorphosis, and basal functions. The findings of this research describe new information on Ae. aegypti physiology which could be useful for the development of new control strategies, particularly in mosquito development and metamorphosis processes.
Subject(s)
Aedes/classification , Aedes/genetics , Insecta/classification , Insecta/genetics , MicroRNAs/genetics , Animals , Evolution, Molecular , Female , Gene Expression Profiling , High-Throughput Nucleotide Sequencing , MaleABSTRACT
Massive worldwide serological testing for SARS-CoV-2 is needed to determine the extent of virus exposure in a particular region, the ratio of symptomatic to asymptomatic infected persons, and the duration and extent of immunity after infection. To achieve this, the development and production of reliable and cost-effective SARS-CoV-2 antigens is critical. We report the bacterial production of the peptide S-RBDN318-V510, which contains the receptor-binding domain of the SARS-CoV-2 spike protein (region of 193 amino acid residues from asparagine-318 to valine-510) of the SARS-CoV-2 spike protein. We purified this peptide using a straightforward approach involving bacterial lysis, his-tag-mediated affinity chromatography, and imidazole-assisted refolding. The antigen performances of S-RBDN318-V510 and a commercial full-length spike protein were compared in ELISAs. In direct ELISAs, where the antigen was directly bound to the ELISA surface, both antigens discriminated sera from non-exposed and exposed individuals. However, the discriminating resolution was better in ELISAs that used the full-spike antigen than the S-RBDN318-V510. Attachment of the antigens to the ELISA surface using a layer of anti-histidine antibodies gave equivalent resolution for both S-RBDN318-V510 and the full-length spike protein. Results demonstrate that ELISA-functional SARS-CoV-2 antigens can be produced in bacterial cultures, and that S-RBDN318-V510 may represent a cost-effective alternative to the use of structurally more complex antigens in serological COVID-19 testing.