Serological Titers Research Articles

Serum Assay Findings after Successful Helicobacter pylori Eradication

Serum pepsinogen (PG), anti-Helicobacter pylori (H. pylori) immunoglobulin G (IgG), and gastrin-17 (G-17) are plasma biomarkers for gastritis. H. pylori serology titers and PG levels increase during active H. pylori infection; moreover, elevated PG II levels indicate a high risk for diffuse-type gastric cancer in East Asian populations. Serum PG I/II ratios and PG I levels decrease with the progression of gastric corpus atrophy; thus, a combination of serum PG I levels ≤70 ng/mL and a PG I/II ratio ≤3 (serologic atrophy) indicates a high risk of intestinal-type gastric cancer. Serum G-17 is often not used as an indicator in H. pylori-seroprevalent populations because it is usually elevated in subjects with H. pylori infections. When H. pylori is eradicated, most patients show a rapid decrease in serum PG II levels and anti-H. pylori IgG titers within a few months. Seroreversion is required for several months to years after regression of H. pylori. Moreover, seroreversion may not always be achieved in all eradicated cases. The serum PG I/II ratio starts to increase after eradication; therefore, serologic atrophy improves accordingly, unless severe atrophy is present. Thus, some eradicated patients may show normal serum assay findings but have a higher risk for developing gastric cancer than H. pylori-naive subjects. Furthermore, serum PG levels decrease after gastrectomy and increase with the intake of certain drugs (e.g., aspirin or acid suppressants) or in renal failure patients. Due to such wide variations, serum assays are inadequate for the confirmation of H. pylori eradication. It is useful when interpreted with gastroscopy and other H. pylori test findings.

S2458 Can SARS-CoV-2 Enterocolitis Trigger New Onset Inflammatory Bowel Disease ?

Introduction: Prevalence of gastrointestinal symptoms in patients infected with SARS-CoV-2 virus is 6.8% - 61.3%. Most common symptoms include diarrhea (8.1% - 33.7%), nausea/vomiting (1.5% - 26.4%), anorexia (12.1% - 26.4%), and abdominal pain (0 – 14.5%). Management involves treating respiratory manifestation of COVID-19, treating co-existing infections, and supportive care. We present a case of severe hemorrhagic enterocolitis managed with a biologic. Case Description/Methods: 47-year-old woman with COVID-19 pneumonia was admitted for extracorporeal membrane oxygenation. She developed copious amounts of watery diarrhea followed by bloody diarrhea. Stool work-up was negative for infectious causes of diarrhea. Colonoscopy revealed diffusely erythematous and friable mucosa with epithelial loss involving the entire colon and distal ileum. She was managed with rectal tube, blood transfusions, parenteral nutrition. Despite escalating doses of numerous anti-diarrheals, topical as well as systemic steroids, copious volumes of bloody diarrhea continued. Repeat colonoscopic biopsies demonstrated CMV-like inclusions with borderline elevated serologic titers. Despite successful eradication of CMV with prolonged courses of ganciclovir and foscarnet, hemorrhagic diarrhea continued. Several upper and lower endoscopies suggested worsening mucosal erythema and friability, predominantly involving small bowel and colon. Given COVID enterocolitis refractory to all the above treatments, induction therapy with a biologic was considered to treat possible de novo inflammatory bowel disease (IBD) versus immune mediated effects of COVID-19 enterocolitis. After induction doses of Ustekinumab, an IL-12 and IL-23 inhibitor, volume of diarrhea reduced and bloody diarrhea resolved, facilitating removal of rectal tube, resumption of oral nutrition, discontinuation of anti-diarrheals. Patient was discharged on maintenance Ustekinumab. Follow-up endoscopic evaluation demonstrated mucosal healing, with epithelial regeneration and chronic inflammatory changes of crypt distortion. Discussion: SARS-CoV-2 infection triggered an inflammatory cascade in the intestinal tract leading to altered or increased immune response, probably on a background of genetic predisposition, in our patient. Initiation of Ustekinumab, IL-23/IL-12 inhibitor, likely resulted in suppression of the severe systemic inflammatory response, resulting in clinical, endoscopic and pathological response.Figure 1.: (a) demonstrates endoscopic appearance of transverse colon with erythema, friability and hemorrhages prior to treatment with biologic (b) demonstrates epithelial denudation with minimal acute inflammation in colonic mucosa prior to treatment with biologic (c) demonstrates endoscopic appearance of transverse colon with resolving erythema after treatment with biologic (d) demonstrates chronic inflammatory changes with crypt architectural distortion and pyloric gland metaplasia after induction of remission with biologic, many months after initial presentation.

In This Issue

In This Issue

Factors associated with the antinuclear antibody (ANA) titer of systemic autoimmune rheumatic diseases in ANA-positive patients after treatment: a retrospective study.

Antinuclear antibodies (ANAs) are a serological hallmark of systemic autoimmune rheumatic diseases (SARDs); however, few studies have investigated their post-treatment levels. The mechanism by which ANA titers are upregulated in SARDs remains unclear. We assessed factors associated with the ANA titer after treatment. In this retrospective study, we analyzed the clinical database of Zhongshan Hospital, Medical College of Xiamen. Demographic data and baseline and 12-month post-treatment ANA titers were collected. Bivariate and multivariate analyses were performed to determine the factors associated with the ANA titer. This study identified 31,923 patients who underwent ANA assay for SARDs screening, and a total of 1043 patients were included in the study. Approximately 16% of the patients showed a decrease in the serological ANA titer. Younger patients (< 20) were 3 × more likely to experience such a decrease (P = 0.005) compared to older patients (≥ 60years). Having a baseline ANA titer > 1:10,000 was associated with an increase likelihood of a decrease in the serological ANA titer compared with baseline ANA titer 1:10,000, 1:3200 and 1:1000 (P < 0.001). We found that a decrease in the serum ANA titer at 12months after treatment for SARDs is associated with age and ANA baseline titers.

Intramuscular vs. Intradermic Needle-Free Vaccination in Piglets: Relevance for Animal Welfare Based on an Aversion Learning Test and Vocalizations.

The aim of the present study was to compare intramuscular injection with a needle and intradermic needle-free vaccinations against porcine reproductive and respiratory syndrome (PRRS) in piglets at 28 days old by studying behavioral and physiological reactions. A total of 72 piglets divided into 2 sex-balanced batches were assessed. Within each batch, the piglets were divided into three treatments, which were Hipradermic (0.2 ml of UNISTRAIN® PRRS vaccine administered with an intradermic needle-free device), Intramuscular (IM, 2.0 ml of vaccine), and Control (not vaccinated). Before the vaccination, the piglets were trained to cross a 4-m-long raceway to perform an aversion learning test. The day of vaccination, the time taken to cross the raceway was registered for each piglet at different times: prior to the vaccination and 10 min, 2, 24, 48, and 72 h after the vaccination, to measure variations in these times as signs of aversion to the vaccination process. Vocalizations, as potential signs of pain, were recorded as well at the end of this raceway to analyze their frequency (Hz), duration, and level of pressure (dB) at the moment of vaccination. Salivary cortisol, as a sign of the HPA-axis activity, was assessed 10 min after the vaccination. In addition, activity budgets, local reaction to the vaccine, and serological titer were also considered in the study. Ten minutes after the vaccination, the IM piglets took longer (p < 0.001) to cross the raceway than did the Hipradermic and Control piglets. Vocalizations were significantly different between the three treatments: the Control piglets produced vocalizations with the lowest frequency (p < 0.001) and level of pressure (p < 0.001), and IM with the highest, with Hipradermic in a significant intermediate position (p < 0.001). Accordingly, the day of the vaccination, IM and Hipradermic animals were lying on the side of the vaccine administration a greater proportion of time than were the Control piglets (10, 11, and 6%, respectively; p = 0.027). Salivary cortisol was not significantly different between treatments. The serum titer of antibodies against the PRRS was higher (p < 0.001) in both vaccinated treatments in comparison to the Control piglets. It is concluded that the Hipradermic needle-free vaccination may result in a less aversive experience in piglets than did intramuscular vaccination.

Anti-HPV16 Antibody Titers Prior to an Incident Cervical HPV16/31 Infection

The goal of this study was to investigate the serological titers of circulating antibodies against human papillomavirus (HPV) type 16 (anti-HPV16) prior to the detection of an incident HPV16 or HPV31 infection amongst vaccinated participants. Patients were selected from a prospective post-HPV vaccine longitudinal cohort at Mount Sinai Adolescent Health Center in Manhattan, NY. We performed a nested case–control study of 43 cases with incident detection of cervical HPV16 (n = 26) or HPV31 (n = 17) DNA who had completed the full set of immunizations of the quadrivalent HPV vaccine (4vHPV). Two control individuals whom had received three doses of the vaccine (HPV16/31-negative) were selected per case, matched on age at the first dose of vaccination and follow-up time in the study: a random control, and a high-risk control that was in the upper quartile of a sexual risk behavior score. We conducted an enzyme-linked immunosorbent assay (ELISA) for the detection of immunoglobulin G (IgG) antibodies specific to anti-HPV16 virus-like particles (VLPs). The results suggest that the average log antibody titers were higher among high-risk controls than the HPV16/31 incident cases and the randomly selected controls. We show a prospective association between anti-HPV16 VLP titers and the acquisition of an HPV16/31 incident infection post-receiving three doses of 4vHPV vaccine.

Early and long term antibody kinetics of asymptomatic and mild disease COVID-19 patients

Most patients infected with SARS-CoV-2 are asymptomatic or mildly symptomatic. However, the early and late antibody kinetics, and the association between antibody levels, clinical symptoms, and disease phase in these patients have not yet been fully defined. Confirmed SARS-CoV-2 patients and their household contacts were evaluated over a period four months. The evaluation procedure included symptom monitoring, viral load and serology analysis every ten days. A total of 1334 serum samples were collected from 135 patients and analyzed using three assays for IgG-N, IgG-S and IgM antibodies. Of the study participants, 97% were seropositive during the study, and two distinct clusters were identified. These clusters were significantly different in their inflammatory related symptoms. Peak IgG-S was 40.0 AU/ml for the non-inflammatory cluster and 71.5 AU/ml for the inflammatory cluster (P = 0.006), whereas IgG-N peaks were 4.3 and 5.87 (P = 0.023) respectively. Finally, a decision tree model was designed to predict the disease phase based on the serological titer levels, and had an overall accuracy of 80.7%. The specific profile of seroconversion and decay of serum antibodies can be used to predict the time-course from the acute infection.

The prognostic value of serological titres in chronic Q fever: treat the patient, not the laboratory data

This commentary, based on the paper by Buijs et al. [1] in the current issue of CMI, discusses the importance of monitoring serological titre changes in patients with chronic Q fever. The authors evaluated phase I IgG dynamics and the association with Q fever complications and therapy failure. Contrary to common perceptions, they found no association between antibody dynamics during the patient follow-up period and various clinical outcomes. These findings challenge current practice, which puts considerable value on serological changes while monitoring the patient's response to therapy in chronic Q fever.

Neutralizing Anti-SARS-CoV-2 Antibody Titer and Reported Adverse Effects, in a Sample of Italian Nursing Home Personnel after Two Doses of the BNT162b2 Vaccine Administered Four Weeks Apart.

Background: The immunization of healthcare workers (HCWs) plays a recognized key role in prevention in the COVID-19 pandemic: in Italy, the vaccination campaign began at the end of December 2020. A better knowledge of the on-field immune response in HCWs, of adverse effects and of the main factors involved is fundamental. Methods: We performed a study on workers at a nursing home in Northern Italy, vaccinated in January–February 2021 with two doses of the BNT162b2 vaccine four weeks apart, instead of the three weeks provided for in the original manufacturer protocol. One month after the second dose, the serological titer of IgG-neutralizing anti-RBD antibodies of the subunit S1 of the spike protein of SARS-CoV-2 was determined. The socio-demographic and clinical characteristics of the subjects and adverse effects of vaccination were collected by questionnaire. Results: In all of the workers, high antibody titer, ranging between 20 and 760 times the minimum protective level were observed. Titers were significantly higher in subjects with a previous COVID-19 diagnosis. Adverse effects after the vaccine were more frequent after the second dose, but no severe adverse effects were observed. Conclusions: The two doses of the BNT162b2 vaccine, even if administered four weeks apart, induced high titers of anti-SARS-CoV-2 neutralizing IgG in all the operators included in the study.

Intraepithelial Lymphocyte Cytometric Pattern Is a Useful Diagnostic Tool for Coeliac Disease Diagnosis Irrespective of Degree of Mucosal Damage and Age-A Validation Cohort.

Introduction: The study of intraepithelial lymphocytes (IEL) by flow cytometry is a useful tool in the diagnosis of coeliac disease (CD). Previous data showed that an increase in %TCRγδ+ and decrease of %CD3− IEL constitute a typical CD cytometric pattern with a specificity of 100%. However, there are no data regarding whether there are differences in the %TCRγδ+ related to sex, age, titers of serology, and degree of histological lesion. Study aims: To confirm the high diagnostic accuracy of the coeliac cytometric patterns. To determine if there are differences between sex, age, serology titers, and histological lesion grade. Results: We selected all patients who fulfilled “4 of 5” rule for CD diagnosis (n = 169). There were no differences in %TCRγδ+ between sexes (p = 0.909), age groups (p = 0.986), serology titers (p = 0.53) and histological lesion grades (p = 0.41). The diagnostic accuracy of complete CD cytometric pattern was: specificity 100%, sensitivity 82%, PPV 100%, NPV 47%. Conclusion: We confirmed, in a validation cohort, the high diagnostic accuracy of complete CD pattern irrespective of sex, age, serology titers, and grade of mucosal lesion.

Assessment of exposure to influenza A viruses in pigs between weaning and market age

Influenza A viruses (IAVs) are common causes of respiratory infection in pigs. The objective of this study was to characterize the circulation of IAVs between weaning and market age on the basis of development of antibody response and molecular epidemiology of detected viruses. Two batches of weaned pigs were followed in the nursery and finisher barns with a sample of 81 and 75 pigs. Nasal swabs and blood samples were collected from individual pigs for virological and serological analyses. A H3N2 subtype virus, of cluster IV, was detected in Study 1, with a maximum of 97.9% identity to HA gene of viruses previously isolated in Ontario. In Study 2, a H1N1 subtype virus, of 2009 H1N1 pandemic lineage, was detected, with a maximum of 97.8% identity to HA gene of viruses previously isolated in Ontario. On the basis of HA gene, it was observed that pigs were being detected with the same virus over time. The existence of antibody titers for IAV other than the isolated one confirmed that more than one subtype can circulate in the same population. In Study 1, pigs with higher numbers of IAV detection had lower serological titers for the same virus that was confirmed to circulate in the nursery (P < 0.01). Thorough knowledge of all endemic viral strains is fundamental for development of infection and disease control, particularly in complex production systems. This may include consideration of sampling and testing strategies which could detect circulation of all IAV variants, even if they have low prevalence.

Crithidia mellificae infection in different mammalian species in Brazil.

Crithidia mellificae, a monoxenous trypanosomatid considered restricted to insects, was recently reported to infect a bat. Herein, C. mellificae has been demonstrated to have a wider range of vertebrate hosts and distribution in Brazilian biomes than once thought. Parasites isolated from haemocultures were characterized using V7V8 SSU rDNA and glyceraldehyde 3-phosphate dehydrogenase genes. Coatis (Nasua nasua) in the Cerrado; marmosets (Callithrix sp.) and bats (Carollia perspicillata, Myotis lavali, M. izecksohni, Artibeus lituratus) in the Atlantic Forest; crab-eating foxes (Cerdocyon thous) and ocelot (Leopardus pardalis) in the Pantanal biomes were infected by trypanosomatids that displayed choanomastigote forms in haemoculture in Giemsa-stained slide smears. Molecular characterization and phylogenetic inference confirmed the infection of C. mellificae in these animals. Moreover, slight differences in C. mellificae sequences were observed. Crithidia mellificae growth curves were counted at 27°C, 36°C and 37°C, and the morphotypes were able to grow and survive for up to 16 days. Serological titers for C. mellificae were observed in nonhuman primates, demonstrating that this parasite is able to induce a humoral immune response in an infected mammal. These results showed that host specificity in trypanosomatids is complex and far from understood.

The prognostic value of serological titres for clinical outcomes during treatment and follow-up of patients with chronic Q fever

ObjectivesWe assessed the prognostic value of phase I IgG titres during treatment and follow-up of chronic Q fever. MethodsWe performed a retrospective cohort study to analyse the course of phase I IgG titres in chronic Q fever. We used a multivariable time-varying Cox regression to assess our primary (first disease-related event) and secondary (therapy failure) outcomes. In a second analysis, we evaluated serological characteristics after 1 year of therapy (fourfold decrease in phase I IgG titre, absence of phase II IgM and reaching phase I IgG titre of ≤1:1024) with multivariable Cox regression. ResultsIn total, 337 patients that were treated for proven (n = 284, 84.3%) or probable (n = 53, 15.7%) chronic Q fever were included. Complications occurred in 190 (56.4%), disease-related mortality in 71 (21.1%) and therapy failure in 142 (42.1%) patients. The course of phase I IgG titres was not associated with first disease-related event (HR 1.00, 95% CI 0.86–1.15) or therapy failure (HR 1.02, 95% CI 0.91–1.15). Similar results were found for the serological characteristics for the primary (HR 0.97, 95% CI 0.62–1.51; HR 1.12, 95% CI 0.66–1.90; HR 0.99, 95% CI 0.57–1.69, respectively) and secondary outcomes (HR 0.86, 95% CI 0.57–1.29; HR 1.37, 95% CI 0.86–2.18; HR 0.80, 95% CI 0.48–1.34, respectively). DiscussionCoxiella burnetii serology does not reliably predict disease-related events or therapy failure during treatment and follow-up of chronic Q fever. Alternative markers for disease management are needed, but, for now, management should be based on clinical factors, PCR results, and imaging results.

Incidence of Infection among Subjects with Helicobacter pylori Seroconversion.

Background/Aims:Helicobacter pylori (H. pylori) seroconversion may occur during screening for gastric cancer. Our study aimed to assess the number of seroconverted subjects with H. pylori and their results in follow-up tests. Methods:Data were consecutively collected on subjects who were H. pylori-seronegative and presented for gastric cancer screening. Subjects who were followed up using the same serology test and pepsinogen (PG) assays on the day of endoscopy were included in the study. Results:During the follow-up of 57.7±21.4 months, 61 (15.0%) of 407 seronegative subjects showed seroconversion. H. pylori infection was detected in six (9.8%) of 61 seroconverted subjects. A diffuse red fundal appearance, with a significant increase in the Kyoto classification scores for gastritis, was observed in the infected subjects (p<0.001). Compared to the false-seropositive subjects, infected subjects showed higher serology titers (p<0.001) and PG II levels (p<0.001) and lower PG I/II ratios (p=0.002), in the follow-up tests. Conclusions:Seroconversion occurred in 3.3% of seronegative subjects per year; however, only 9.8% had H. pylori infection. The majority (90.2%) of the seroconverted subjects showed false seropositivity without significant changes in the follow-up test results. The diffuse red fundal appearance could be an indicator of H. pylori infection.

The Imbalance of Circulating Follicular T Helper Cell Subsets in Primary Sjögren's Syndrome Associates With Serological Alterations and Abnormal B-Cell Distribution.

Since B-cell hyperactivity and pathologic antibody response are key features in the immunopathogenesis of primary Sjögren’s syndrome (pSS), the role of follicular T helper (TFH) cells as efficient helpers in the survival and differentiation of B cells has emerged. Our aim was to investigate whether a change in the balance of circulating (c)TFH subsets and follicular regulatory T (TFR) cells could affect the distribution of B cells in pSS. Peripheral blood of 38 pSS patients and 27 healthy controls was assessed for the frequencies of cTFH cell subsets, TFR cells, and certain B cell subpopulations by multicolor flow cytometry. Serological parameters, including anti-SSA, anti-SSB autoantibodies, immunoglobulin, and immune complex titers were determined as part of the routine diagnostic evaluation. Patients with pSS showed a significant increase in activated cTFH cell proportions, which was associated with serological results. Frequencies of cTFH subsets were unchanged in pSS patients compared to healthy controls. The percentages and number of cTFR cells exhibited a significant increase in autoantibody positive patients compared to patients with seronegative pSS. The proportions of transitional and naïve B cells were significantly increased, whereas subsets of memory B cells were significantly decreased and correlated with autoantibody production. Functional analysis revealed that the simultaneous blockade of cTFH and B cell interaction with anti-IL-21 and anti-CD40 antibodies decreased the production of IgM and IgG. Imbalance in TFH subsets and TFR cells indicates an ongoing over-activated humoral immune response, which contributes to the characteristic serological manifestations and the pathogenesis of pSS.

Tandem high-dose influenza vaccination is associated with more durable serologic immunity in patients with plasma cell dyscrasias

Patients with plasma cell dyscrasias (PCDs) experience an increased burden of influenza, and current practice of single-dose annual influenza vaccination yields suboptimal protective immunity in these patients. Strategies to improve immunity to influenza in these patients are clearly needed. We performed a randomized, double-blind, placebo-controlled clinical trial comparing tandem Fluzone High-Dose influenza vaccination with standard-of-care influenza vaccination. Standard-of-care vaccination was single-dose age-based vaccination (standard dose, <65 years; high dose, ≥65 years), and patients in this arm received a saline placebo injection at 30 days. A total of 122 PCD patients were enrolled; 47 received single-dose standard-of-care vaccination, and 75 received 2 doses of Fluzone High-Dose vaccine. Rates of hemagglutinin inhibition (HAI) titer seroprotection against all 3 strains (H1N1, H3N2, and influenza B) were significantly higher for patients after tandem high-dose vaccination vs control (87.3% vs 63.2%; P = .003) and led to higher seroprotection at the end of flu season (60.0% vs 31.6%; P = .04). These data demonstrate that tandem high-dose influenza vaccination separated by 30 days leads to higher serologic HAI titer responses and more durable influenza-specific immunity in PCD patients. Similar vaccine strategies may also be essential to achieve protective immunity against other emerging pathogens such as novel coronavirus in these patients. This trial was registered at www.clinicaltrials.gov as #NCT02566265.

Breadth and function of antibody response to acute SARS-CoV-2 infection in humans.

Serological and plasmablast responses and plasmablast-derived IgG monoclonal antibodies (MAbs) have been analysed in three COVID-19 patients with different clinical severities. Potent humoral responses were detected within 3 weeks of onset of illness in all patients and the serological titre was elicited soon after or concomitantly with peripheral plasmablast response. An average of 13.7% and 3.5% of plasmablast-derived MAbs were reactive with virus spike glycoprotein or nucleocapsid, respectively. A subset of anti-spike (10 of 32) antibodies cross-reacted with other betacoronaviruses tested and harboured extensive somatic mutations, indicative of an expansion of memory B cells upon SARS-CoV-2 infection. Fourteen of 32 anti-spike MAbs, including five anti-receptor-binding domain (RBD), three anti-non-RBD S1 and six anti-S2, neutralised wild-type SARS-CoV-2 in independent assays. Anti-RBD MAbs were further grouped into four cross-inhibiting clusters, of which six antibodies from three separate clusters blocked the binding of RBD to ACE2 and five were neutralising. All ACE2-blocking anti-RBD antibodies were isolated from two recovered patients with prolonged fever, which is compatible with substantial ACE2-blocking response in their sera. Finally, the identification of non-competing pairs of neutralising antibodies would offer potential templates for the development of prophylactic and therapeutic agents against SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 prevalence in 1170 asymptomatic Norwegian conscripts.

BackgroundAccurate estimates of SARS‐CoV‐2 infection in different population groups are important for the health authorities. In Norway, public infection control measures have successfully curbed the pandemic. However, military training and service are incompatible with these measures; therefore extended infection control measures were implemented in the Norwegian Armed Forces. We aimed to describe these measures, discuss their value, and investigate the polymerase chain reaction (PCR) prevalence and seroprevalence of SARS‐CoV‐2, as well as changes in antibody titer levels over the 6‐week military training period in a young, asymptomatic population of conscripts.MethodsIn April 2020, 1170 healthy conscripts (median age 20 years) enrolled in military training. Extended infection control measures included a pre‐enrollment telephone interview, self‐imposed quarantine, questionnaires, and serial SARS‐CoV‐2 testing. At enrollment, questionnaires were used to collect information on symptoms, and SARS‐CoV‐2 rapid antibody testing was conducted. Serial SARS‐CoV‐2 PCR and serology testing were used to estimate the prevalence of confirmed SARS‐CoV‐2 and monitor titer levels at enrollment, and 3 and 6 weeks thereafter.ResultsAt enrollment, only 0.2% of conscripts were SARS‐CoV‐2 PCR‐positive, and seroprevalence was 0.6%. Serological titer levels increased nearly 5‐fold over the 6‐week observation period. Eighteen conscripts reported mild respiratory symptoms during the 2 weeks prior to enrollment (all were PCR‐negative; one was serology‐positive), whereas 17 conscripts reported respiratory symptoms and nine had fever at enrollment (all were PCR‐ and serology‐negative).ConclusionsThe prevalence of SARS‐CoV‐2 was less than 1% in our sample of healthy Norwegian conscripts. Testing of asymptomatic conscripts seems of no value in times of low COVID‐19 prevalence. SARS‐CoV‐2 antibody titer levels increased substantially over time in conscripts with mild symptoms.

Evaluation of Colostral Immunity Against Equine Herpesvirus Type 1 (EHV-1) in Martina Franca's Foals.

Eight Martina Franca pregnant jennies were selected in order to evaluate the transfer of colostral antibodies against equine herpesvirus type 1 in their relative foals after immunization with a commercial inactivated vaccine, compared with an unvaccinated group. Samples of serum and colostrums/milk were collected from jennies and foals under study starting from 10 min before and up to 21 days after the foaling. Specific anti-EHV-1 antibody titers were evaluated by means of a serum neutralization test, and the results obtained from both groups were analyzed. The serological titers in the vaccinated jennies was significantly higher (p < 0.01). No significant differences were found in the specific time-point intervals in both groups examined (p > 0.05). The antibody titers in milk at the time of delivery and subsequent withdrawal (T0 and T1) were very high in both groups, but no significant differences were found between the two groups (p > 0.05). In the foal sera, a significant difference was found between foals in the vaccinated group compared with those in the unvaccinated group (p < 0.05). Finally, a significant correlation (p < 0.05) was observed between the antibody titers found in serum and colostrum of jennies and the foal titers in the first time-point sampling (up to 12 h after foaling). The results confirm a substantial homology in the antibody production compared with other most investigated equids, highlighting the efficacy of the vaccination against EHV-1 of the jennies to ensure the protective immunity to their foals during the first weeks after delivery.

Antibody Response Against Sars-Cov-2 in Convalescent Plasma Donors: Preliminary Results from a Single Center in Midwest Brazil

In March 2020, COVID-19 was declared a pandemic by the WHO. Since then, efforts have been made to increase our knowledge of the disease. The convalescent plasma (CP) donation involves a series of criteria for donor eligibility, such as pre-donation and serological tests. Currently, the antibody response against SARS-CoV-2 remains poorly understood and the usefulness of serological tests is unclear (Long, et al. Nature Medicine, 2020). Based on donor eligibility, one can better assess the antibody response to SARS-CoV-2 from post-infection candidates.This is an observational, prospective study, without intervention. From 06/26/2020 to 07/31/2020, serological data of candidates for CP donation were collected. Recovered COVID-19 patients who had been previously tested were interviewed. RT-PCR and serological test (chemiluminescence immunoassays) for SARS-CoV-2 were carried out to verify their eligibility for CP collection. The data were related to the time of the onset of symptoms and the collection of the material. Subjects with non-detectable RT-PCR and reagent IgG were considered eligible. Reference values were IgM > 1.2 AU/mL and IgG > 1.4 AU/mL.The characteristics of the candidates are summarized in Table 1. Of 234 interviewed subjects, 70 were screened for pre-collection tests, 49 were male. The average age was 36 (20 - 57). After serological screening, 44/70 (62.8%) were considered eligible for CP donation. The reasons for ineligibility were: 17/70 (24.3%) non-reagent IgG, 4/70 (5.7%) with detectable RT-PCR and 5/70 (7.1%) due to reasons in clinical screening.The median between the onset of symptoms and the serology sample collection was 32.5 (21 - 77) days, (IQR 28.75 to 37.25). Those who were more likely to be eligible to donate were the subjects who had a longer time interval between the symptoms onset and the sample collection (p <0.012).Although viral clearance in the upper airways is expected from the 10th day of symptom onset, only 50% of patients will have an undetectable test (Özçürümez, et al. J Allergy Clin Immunol. 2020). In our sample, 5.7% (4/70) of the subjects had detectable RT-PCR, which can represent residual viral genome and not active infection.We observed that 20% of the subjects samples were non-reagent. Those who were tested up to the 21st of the onset of symptoms might not have had seroconversion yet. For those tested after the 28th day, we can infer that the antibodies had already been cleared. Some authors state that patients who had mild infections may react with less antibodies (Özçürümez, et al. J Allergy Clin Immunol. 2020), which could explain this fact. Likewise, it was not possible to relate serological titers to the severity of the disease, as this was not one of the selection criteria.In 40/70 donors (57.2%) IgM remained above 1.2 AU / mL after the 21st day of symptom onset. Interestingly, 2 of these had only reagent IgM after the 36th day of symptom onset. Most subjects who had reagent IgM after the 21st of symptoms also had reagent IgG. We inferred that they were in a vigorous convalescence phase.In addition, 75.7% of the subjects presented reagent IgG regardless of the date of onset of symptoms. Most of them had both reagent IgM and IgG. Only one donor's (1.4%) IgM and IgG were non-reagent 21 days after the onset of symptoms.As we did not collect serial samples, we could not verify the average amount of days for seroconversion to take place. Some authors recommend that the single collection should occur at least 21 days after the onset of symptoms, so seroconversion is observed (Deeks, et al., Cochrane Database Syst Rev. 2020). In our sample, 4 donors (5%) collected the samples on the 21st day after the symptom onset. Of these, 3 had seroconversion, 2 with IgM and IgG, 1 with IgG and 1 with reagent IgM.The values suggest that the subjects who could donate CP were those that presented a longer time interval between the onset of symptoms and the blood sample collection, in comparison to those who could not (p=0,012 and 0,409, respectively). The median of days between symptom onset and serology testing was also higher in the non-eligible group. Besides, the eligible group had a higher average concentration of IgM and IgG compared to the non-eligible one.In conclusion, regarding the serological criteria, about 25% of the studied population could not donate CP. Although a single serology sample collection after the 21st day of symptom onset is recommended, only 1 candidate did not show seroconversion.DisclosuresNo relevant conflicts of interest to declare.