A bead-based multiplex assay covering all coronaviruses pathogenic for humans for sensitive and specific surveillance of SARS-CoV-2 humoral immunity

Serological assays measuring antibodies against SARS-CoV-2 are key to describe the epidemiology, pathobiology or induction of immunity after infection or vaccination. Of those, multiplex assays targeting multiple antigens are especially helpful as closely related coronaviruses or other antigens can be analysed simultaneously from small sample volumes, hereby shedding light on patterns in the immune response that would otherwise remain undetected. We established a bead-based 17-plex assay detecting antibodies targeting antigens from all coronaviruses pathogenic for humans: SARS-CoV-2, SARS-CoV, MERS-CoV, HCoV strains 229E, OC43, HKU1, and NL63. The assay was validated against five commercial serological immunoassays, a commercial surrogate virus neutralisation test, and a virus neutralisation assay, all targeting SARS-CoV-2. It was found to be highly versatile as shown by antibody detection from both serum and dried blot spots and as shown in three case studies. First, we followed seroconversion for all four endemic HCoV strains and SARS-CoV-2 in an outbreak study in day-care centres for children. Second, we were able to link a more severe clinical course to a stronger IgG response with this 17-plex-assay, which was IgG1 and IgG3 dominated. Finally, our assay was able to discriminate recent from previous SARS-CoV-2 infections by calculating the IgG/IgM ratio on the N antigen targeting antibodies. In conclusion, due to the comprehensive method comparison, thorough validation, and the proven versatility, our multiplex assay is a valuable tool for studies on coronavirus serology.

Flexible upscaling of laboratory PCR testing capacity at the Robert Koch Institute during the SARS-CoV-2 pandemic

BACKGROUND

Over the course of the COVID-19 pandemic, laboratories worldwide have been facing an unprecedented increase in demand for PCR testing because of the high importance of diagnostics for prevention and control of virus spread. Moreover, testing demand has been varying considerably over time, depending on the epidemiological situation, rendering efficient resource allocation difficult. Here, we present a scalable workflow which we implemented in our laboratory to increase PCR testing capacity while maintaining high flexibility regarding the number of samples to be processed.

METHODS

We compared the performance of five automated extraction instruments, using dilutions of SARS-CoV-2 cell culture supernatant as well as clinical samples. To increase PCR throughput, we combined the two duplex PCR reactions of our previously published SARS-CoV-2 PCR assay into one quadruplex reaction and compared their limit of detection as well as their performance on the detection of low viral loads in clinical samples. Furthermore, we developed a sample pooling protocol with either two or four samples per pool, combined with a specifically adapted SARS-CoV-2 quadruplex PCR assay, and compared the diagnostic sensitivity of pooled testing and individual testing.

RESULTS

All tested automated extraction instruments yielded comparable results regarding the subsequent sensitivity of SARS-CoV-2 detection by PCR. While the limit of detection of the quadruplex SARS-CoV-2 PCR assay (E-Gene assay: 28.7 genome equivalents (ge)/reaction, orf1ab assay: 32.0 ge/reaction) was slightly higher than that of our previously published duplex PCR assays (E-Gene assay: 9.8 ge/reaction, orf1ab assay: 6.6 ge/reaction), the rate of correctly identified positive patient samples was comparable for both assays. Sample pooling with optimized downstream quadruplex PCR showed no loss in diagnostic sensitivity compared to individual testing.

CONCLUSION

Specific adaptation of PCR assays can help overcome the potential loss of sensitivity due to higher levels of PCR multiplexing or sample dilution in pooled testing. Combining these adapted PCR assays with different sample processing strategies provides a simple and highly adjustable workflow for resource-efficient SARS-CoV-2 diagnostics. The presented principles can easily be adopted in a variety of laboratory settings as well as be adapted to pathogens other than SARS-CoV-2, making it feasible for any laboratory that conducts PCR diagnostics.

Effectiveness of vaccines in preventing hospitalization due to COVID-19: A multicenter hospital-based case-control study, Germany, June 2021 to January 2022

We included 852 patients in a prospectively recruiting multicenter matched case-control study in Germany to assess vaccine effectiveness (VE) in preventing COVID-19-associated hospitalization during the Delta-variant dominance. The two-dose VE was 89 % (95 % CI 84-93 %) overall, 79 % in patients with more than two comorbidities and 77 % in adults aged 60-75 years. A third dose increased the VE to more than 93 % in all patient-subgroups.

Evaluation of 11 commercially available PCR kits for the detection of monkeypox virus DNA, Berlin, July to September 2022

Before the international spread of monkeypox in May 2022, PCR kits for the detection of orthopoxviruses, and specifically monkeypox virus, were rarely available. Here we describe the evaluation of 11 recently developed commercially available PCR kits for the detection of monkeypox virus DNA. All tested kits are currently intended for research use only and clinical performance still needs to be assessed in more detail, but all were suitable for diagnostics of monkeypox virus, with variations in specificity rather than sensitivity.

Resource-efficient internally controlled in-house real-time PCR detection of SARS-CoV-2

Background

The reliable detection of SARS-CoV-2 has become one of the most important contributions to COVID-19 crisis management. With the publication of the first sequences of SARS-CoV-2, several diagnostic PCR assays have been developed and published. In addition to in-house assays the market was flooded with numerous commercially available ready-to-use PCR kits, with both approaches showing alarming shortages in reagent supply.

Aim

Here we present a resource-efficient in-house protocol for the PCR detection of SARS-CoV-2 RNA in patient specimens (RKI/ZBS1 SARS-CoV-2 protocol).

Methods

Two duplex one-step real-time RT-PCR assays are run simultaneously and provide information on two different SARS-CoV-2 genomic regions. Each one is duplexed with a control that either indicates potential PCR inhibition or proves the successful extraction of nucleic acid from the clinical specimen.

Results

Limit of RNA detection for both SARS-CoV-2 assays is below 10 genomes per reaction. The protocol enables testing specimens in duplicate across the two different SARS-CoV-2 PCR assays, saving reagents by increasing testing capacity. The protocol can be run on various PCR cyclers with several PCR master mix kits.

Conclusion

The presented RKI/ZBS1 SARS-CoV-2 protocol represents a cost-effective alternative in times of shortages when commercially available ready-to-use kits may not be available or affordable.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-021-01559-3.

Hyperactive delirium in patients after non-traumatic subarachnoid hemorrhage

PURPOSE

Hyperactive delirium is common after subarachnoid hemorrhage (SAH). We aimed to identify risk factors for delirium and to evaluate its impact on outcome.

METHODS

We collected daily Richmond Agitation Sedation Scale (RASS) and Intensive Care Delirium Screening Checklist (ICDSC) scores in 276 SAH patients. Hyperactive delirium was defined as ICDSC ≥4 when RASS was >0. We investigated risk factors for delirium and its association with 3-month functional outcome using generalized linear models.

RESULTS

Patients were 56 (IQR 47-67) years old and had a Hunt&Hess (H&H) grade of 3 (IQR 1-5). Sixty-five patients (24%) developed hyperactive delirium 6 (IQR 3-16) days after SAH. In multivariable analysis, mechanical ventilation>48 h (adjOR = 4.46; 95%-CI = 1.89-10.56; p = 0.001), the detection of an aneurysm (adjOR = 4.38; 95%-CI = 1.48-12.97; p = 0.008), a lower H&H grade (adjOR = 0.63; 95%-CI = 0.48-0.83; p = 0.001) and a pre-treated psychiatric disorder (adjOR = 3.17; 95%-CI = 1.14-8.83; p = 0.027) were associated with the development of delirium. Overall, delirium was not associated with worse outcome (p = 0.119). Interestingly, patients with delirium more often had a modified Rankin Scale Score (mRS) of 1-3 (77%) compared to an mRS of 0 (14%) or 4-6 (9%).

CONCLUSION

Our data indicate that hyperactive delirium is common after SAH patients and requires a certain degree of brain connectivity based ono the highest prevalence found in SAH patients with intermediate outcomes.