Traceable value of immunoglobulin G against receptor-binding domain of SARS-CoV-2 confirmation and application to point-of-care testing system development

A highly purified and bioactive immunoglobulin G monoclonal antibody against receptor-binding domain of SARS-CoV-2 (RBD-IgG-MAb) has been accurately quantified by amino acid determination using isotope dilution liquid chromatography-mass spectrometry. Absolute quantification of RBD-IgG-MAb was achieved by averaging 4 amino acid certified reference materials, which allows the quantitative value (66.1 ± 5.8 μg/L) to be traced to SI unit (mol). Afterwards, the RBD-IgG-MAb was employed as control and calibration compound for the development of a point-of-care testing (POCT) system based on colloidal gold lateral flow immunoassay, which aimed to rapidly and accurately detect the level of protective RBD-IgG after vaccination. Under the detection parameters, a sigmoidal curve has been plotted between signal intensity and the logarithmic concentration for quantitative detection with the limit of detection of about 0.39 μg/mL. The relative standard deviations of intra-assay and inter-assay were lower than 2.3% and 14%, and the recoveries ranged from 87 to 100%, respectively. Fingertip blood samples from 37 volunteers after vaccination were analyzed by the POCT system; results showed that levels of RBD-IgG in 33 out of 37 samples ranged from 0.45 to 2.46 μg/mL with the average level of 0.91 μg/mL. The developed POCT system has been successfully established with the quantity-traceability RBD-IgG-MAb as control and calibration compound, and the scientific contribution of this work can be promoted to other areas.

Absence of neutralizing antibodies against the Omicron SARS-CoV-2 variant in convalescent sera from individuals infected with the ancestral SARS-CoV-2 virus or its Gamma variant

OBJECTIVES

The aim of the present study was to evaluate if neutralizing antibody responses induced by infection with the SARS-CoV-2 strain that was dominant at the beginning of the pandemic or by the Gamma variant was effective against the Omicron variant.

METHODS

Convalescent sera from 109 individuals, never exposed to a SARS-CoV-2 vaccine, who had mild or moderate symptoms not requiring hospitalization following either a documented SARS-CoV-2 ancestral strain infection or a Gamma variant infection, were assayed for in vitro neutralizing antibody activity against their original strains and the Omicron variant.

RESULTS

Following an infection with the ancestral strain, 56 (93.3%), 45 (77.6%) and 1 (1.7%) serum sample were positive for neutralizing antibodies against the ancestral, Gamma variant, and Omicron variant, respectively. After infection with the Gamma variant, 43 (87.8%) and 2 (4.1%) sera were positive for neutralizing antibodies against the Gamma and Omicron variants, respectively.

CONCLUSIONS

Neutralizing antibodies generated following mild or moderate infection with the SARS-CoV-2 ancestral strain or the Gamma variant are not protective against the Omicron variant.

[How well are patients with inflammatory rheumatic diseases protected against measles?]

Hintergrund

Patienten mit entzündlich rheumatischen Erkrankungen haben aufgrund ihrer Autoimmunerkrankung, aber auch bedingt durch die immunsuppressive Medikation ein erhöhtes Infektrisiko. Obwohl Impfungen in der Primärprophylaxe von Infektionen bekanntermaßen effektiv sind, ist die Impfrate in Deutschland generell zu niedrig. Wegen des zuletzt zunehmenden, teils epidemieartigen Auftretens von Masern ist die Lebendimpfung gegen Masern in Deutschland seit Kurzem gesetzlich vorgeschrieben.

Fragestellung

Wie viele Patienten mit entzündlich rheumatischen Erkrankungen sind aktuell ausreichend gegen Masern geschützt?

Methode

Patienten mit entzündlich rheumatischen Erkrankungen des Rheumazentrums Ruhrgebiet wurden zwischen Dezember 2017 und Oktober 2018 prospektiv und konsekutiv eingeschlossen. Dabei wurden Daten zu Erkrankung und Therapie auf Ebene von Substanzklassen sowie die Impf- und Infektanamnese erhoben. Alle Angaben zu Impfungen wurden im Impfpass kontrolliert. Antikörpertiter gegen Masern wurden mit ELISA bestimmt. Als Schwellenwert für einen ausreichenden Schutz gegen Masern wurden 150 mIU/ml festgelegt.

Ergebnis

Von 975 Patienten konnten 540 (55,4 %) einen Impfausweis vorlegen. Bei 201 Patienten mit Ausweis (37,2 %) lagen dokumentierte Impfungen seit Geburt vor. Insgesamt hatten 45 von 267 nach 1970 geborene Patienten (16,9 %) einen suffizienten Impfschutz gegen Masern. Die anamnestischen Angaben zu einer Masernerkrankung in der Kindheit differenzierten nicht zwischen Patienten mit und ohne protektiven Masern-IgG-Antikörpern. Protektive Masern-IgG-Antikörper wurden bei 901 Patienten von 928 Patienten mit Messung der Masern-IgG-Antikörperspiegel (97,1 %) nachgewiesen. Die unterschiedlichen Wirkprinzipien der aktuellen immunsuppressiven Therapie hatten darauf keinen Einfluss.

Diskussion

Diese Daten zeigen, dass mindestens 2,9 % der Patienten keinen ausreichenden Schutz gegen Masern haben. Interessanterweise hatte die Mehrheit der nach 1970 geborenen Patienten protektive Antikörper trotz fehlenden Impfschutzes gegen Masern. Die Anstrengungen sowohl im primär- als auch im fachärztlichen Bereich sollten dringend verstärkt werden, um eine adäquate Infektionsprophylaxe bei besonders gefährdeten Patienten gewährleisten zu können.

Recurrent pneumonia in a patient with new coronavirus infection after discharge from hospital for insufficient antibody production: a case report

BACKGROUND

The rapid spread of coronavirus disease 2019 (COVID-19) was declared as an emerging public health threat by the World Health Organization. As various measures have been taken successfully to combat the epidemic caused by SARS-CoV-2, a growing number of fully recovered patients have been discharged from hospitals. However, some of them have relapsed. Little is known about the causes that triggered the relapse.

CASE PRESENTATION

We report a case of a 40 years old man who suffered from recurrent pulmonary infection with progression of lesions on chest computed tomography (CT), elevated levels of ferritin and IL2R, reduced lymphocyte count and positive oropharyngeal swab test for SARS-CoV-2 again after 5 days discharge from hospital. The anti-SARS-CoV-2 antibody level of this patient was very low at the time of relapse, suggesting a weak humoral immune response to the virus. Total exon sequencing revealed mutations in TRNT1 gene, which may be responsible for B cell immunodeficiency. Therefore, uncleared SARS-CoV-2 at his first discharge was likely to lead to his recurrence. However, viral superinfection and non-infectious organizing pneumonia could not be completely excluded.

CONCLUSION

COVID-19 relapse may occur in a part of discharged patients with low titers of anti-SARS-CoV-2 antibodies. These patients should be maintained in isolation for longer time even after discharge. A more sensitive method to detect SARS-CoV-2 needs to be established and serological testing for specific antibodies may be used as a reference to determine the duration of isolation.

Long-Term Efficacy and Safety of Immunomodulatory Therapy for Atherosclerosis

BACKGROUND AND AIMS

The long-term effect of immune tolerance has not been explored so far in atherosclerosis. In the present study, we assessed the effect of mucosal tolerance to a multi antigenic construct expressing three peptides from ApoB, HSP60, and outer membrane protein from Chlamydia pneumonia (AHC) for 30 weeks at every 6-week interval to understand the kinetics of immune modulation in disease progression. The safety profile of the molecule was also evaluated in mice.

METHODS

Apob^tm2SgyLdlr^tm1Her/J mice (5-6 weeks) were orally dosed with multi antigenic construct (AHC) molecule on alternate days, followed by high-fat diet feeding to initiate atherosclerosis.

RESULTS

Treated animals showed an efficient reduction in plaque growth and lipid accumulation at 6 weeks (49%, p < 0.01) and 12 weeks (42.3%, p < 0.01) which decreased to 29% (p = 0.0001) at 18 weeks and at later time points. Macrophage accumulation was significantly lower at all time points (53% at 12 weeks to 27% at 30 weeks). Regulatory T cells increased in the spleen following treatment until 12 weeks (week 0 (2.57 ± 0.18 vs. 6.36 ± 0.03, p = 0.02), week 6 (4.52 ± 0.2 vs. 8.87 ± 0.32, p = 0.02), and week 12 (8.74 ± 0.37 vs. 15.4 ± 0.27, p = 0.02)) but showed a decline later. A similar trend was observed with tolerogenic dendritic cells. We observed an increase in antibody levels to low-density lipoprotein and oxidized LDL at later stages. AHC molecule was found to be safe in acute and repeated dose toxicity studies.

CONCLUSIONS

Our results suggest that immune tolerance to AHC protein by oral administration is able to provide efficient atheroprotection up to 18 weeks and moderately at later stages. Apart from immune regulatory cells, protective antibodies may also have a role in controlling atherosclerosis.

Development of a high-throughput opsonophagocytic assay for the determination of functional antibody activity against Streptococcus pyogenes using bioluminescence

The lack of standardised protocols for the assessment of functional antibodies has hindered Streptococcus pyogenes research and the development of vaccines. A robust, high throughput opsonophagocytic bactericidal assay to determine protective antibodies in human and rabbit serum has been developed that utilises bioluminescence as a rapid read out.

Cattle rabies vaccination--A longitudinal study of rabies antibody titres in an Israeli dairy herd

In contrast to many regions of the world where rabies is endemic in terrestrial wildlife species, wildlife rabies has been controlled in Israel by oral rabies vaccination programs, but canine rabies is re-emerging in the northern area of the Golan Heights. From 2009 to 2014 there were 208 animal rabies cases in Israel; 96 (46%) were considered introduced primary cases in dogs, triggering 112 secondary cases. One third (37/112) of the secondary cases were in cattle. Rabies vaccination is voluntary for cattle in Israel, except those on public exhibit. Rabies vaccination schedules for cattle vary based on farm practices and perception of risk. In this study 59 cattle from a dairy farm which routinely vaccinates against rabies were assigned into six groups according to age and vaccination histories. Four groups contained adult cows which had received one previous rabies vaccination, one group of adults had received two previous vaccinations, and one group was unvaccinated calves. Serum samples were collected and the cows were vaccinated with a commercial rabies vaccine. Sera were again collected 39 days later and the calf group re-vaccinated and re-sampled 18 days later. Sera were analyzed for the presence of rabies virus neutralizing antibodies using the rapid immunofluorescent antibody test. Cattle with antibody titres ≥ 0.5 IU/ml were considered to be protected against rabies. Twenty-six of 27 adult cattle (96%) vaccinated once at less than five months old did not have protective titres. Sixty percent (6/10) cattle vaccinated once at around six months of age did have adequate titres. Cattle previously vaccinated twice (n=10; 100%) with an 18 month interval between inoculations, had protective titres and protective antibody titres following booster vaccination (n=51; 100%). The anamnestic response of cattle to a killed rabies vaccine was not affected by the time interval between vaccinations, which ranged from 12 to 36 months. These results suggest that calves from vaccinated cows should not be vaccinated before six months old to avoid maternal antibody interference. Whilst most cattle older than six months old will be protected after a single inoculation, a second inoculation ensures a higher antibody levels for improved protection. Cattle receiving an effective priming dose responded well to a booster up to 36 months later. Such results demonstrate the effectiveness of rabies vaccination in cattle and the added value of a second dose to ensure a prolonged immune response against rabies.