Differential abundance of IgG antibodies against the spike protein of SARS-CoV-2 and seasonal coronaviruses in patients with fatal COVID-19

Infection with the novel pandemic SARS-CoV-2 virus has been shown to elicit a cross-reactive immune response that could lead to a back-boost of memory recall to previously encountered seasonal (endemic) coronaviruses (eCoVs). Whether this response is associated with a fatal clinical outcome in patients with severe COVID-19 remains unclear. In a cohort of hospitalized patients, we have previously shown that heterologous immune responses to eCoVs can be detected in severe COVID-19. Here, we report that COVID-19 patients with fatal disease have decreased SARS-CoV-2 neutralizing antibody titers at hospital admission, which correlated with lower SARS-CoV-2 spike-specific IgG and was paralleled by a relative abundance of IgG against spike protein of eCoVs of the genus Betacoronavirus. Additional research is needed to assess if eCoV-specific back-boosted IgG is a bystander phenomenon in severe COVID-19, or a factor that influences the development of an efficient anti-viral immune response.

Impaired SARS-CoV-2 specific T-cell response in patients with severe COVID-19

Cellular immune responses are of pivotal importance to understand SARS-CoV-2 pathogenicity. Using an enzyme-linked immunosorbent spot (ELISpot) interferon-γ release assay with wild-type spike, membrane and nucleocapsid peptide pools, we longitudinally characterized functional SARS-CoV-2 specific T-cell responses in a cohort of patients with mild, moderate and severe COVID-19. All patients were included before emergence of the Omicron (B.1.1.529) variant. Our most important finding was an impaired development of early IFN-γ-secreting virus-specific T-cells in severe patients compared to patients with moderate disease, indicating that absence of virus-specific cellular responses in the acute phase may act as a prognostic factor for severe disease. Remarkably, in addition to reactivity against the spike protein, a substantial proportion of the SARS-CoV-2 specific T-cell response was directed against the conserved membrane protein. This may be relevant for diagnostics and vaccine design, especially considering new variants with heavily mutated spike proteins. Our data further strengthen the hypothesis that dysregulated adaptive immunity plays a central role in COVID-19 immunopathogenesis.

[A 30-year-old man with a puddle of pleural effusion]

BACKGROUND

The pleural effusion found in urinothorax is traditionally classified as transudate. In some cases, however, the Light-criteria can show an exudate.

CASE DESCRIPTION

We describe the case of a 30-year-old man who attended the emergency department with shortness of breath and severe, diffuse, chest pain; this occurred two days after he had undergone a left-sided percutaneous nephrolithotomy by a urologist. A chest X-ray showed pleural effusion in the left basal region. Based on the Light-criteria, this effusion was an exudate. We made the diagnosis of urinothorax following percutaneous nephrolithotomy.

CONCLUSION

When urinothorax is suspected, biochemical analysis can reveal either a transudate or an exudate. The pleural fluid/serum creatinine ratio can be a valuable addition to the Light-criteria in this setting. The Light-criteria should always be interpreted in a clinical context.

Clinical relevance of Corynebacterium pseudodiphtheriticum in lower respiratory tract specimens

BACKGROUND

Corynebacterium pseudodiphtheriticum may be present as commensal flora of the respiratory tract and therefore it may be difficult to assess clinical relevance when it is cultured from lower respiratory tract specimens. Our objective was to determine the clinical relevance of C. pseudodiphtheriticum as a lower respiratory tract pathogen and to define patients at risk of developing lower respiratory tract infections caused by C. pseudodiphtheriticum.

METHODS

We retrospectively identified all lower respiratory tract cultures positive for C. pseudodiphtheriticum over a 10-year period and assessed clinical relevance by predefined criteria.

RESULTS

Clinical relevance was likely or possible in 86% of patients. Pre-existent comorbidity was present in 86% of patients, mostly underlying cardiac or pulmonary disease. All isolates were susceptible to amoxicillin.

CONCLUSION

C. pseudodiphtheriticum should be considered a clinically relevant pathogen when cultured from the lower respiratory tract in symptomatic patients.

Diagnosis of Coxiella burnetii infection: comparison of a whole blood interferon-gamma production assay and a Coxiella ELISPOT

Diagnosis of ongoing or past infection with Coxiella burnetii, the causative agent of Q fever, relies heavily on serology: the measurement of C. burnetii-specific antibodies, reflecting the host’s humoral immune response. However, cell-mediated immune responses play an important, probably even more relevant, role in infections caused by the intracellular C. burnetii bacterium. Recent studies have investigated interferon-gamma (IFN-γ) based assays, including a whole-blood IFN-γ production assay and a Coxiella enzyme-linked immunospot (Coxiella ELISPOT), as potential diagnostic tools for Q fever diagnosis. Both are in-house developed assays using stimulating antigens of different origin. The main objective of this study was to compare the test performance of the IFN-γ production assay and the Coxiella ELISPOT for detecting a cellular immune response to C. burnetii in Q fever patients, and to assess the correlation between both assays. To that end, both tests were performed in a well-defined patient group of chronic Q fever patients (n = 16) and a group of healthy seronegative individuals (n = 17). Among patients, both the Coxiella ELISPOT and the IFN-γ production assay detected positive response in 14/16. Among controls, none were positive in the Coxiella ELISPOT, whereas the IFN-γ production assay detected positive results in 1/17 and 3/17, when using Henzerling and Nine Mile as stimulating antigens, respectively. These results suggest the Coxiella ELISPOT has a somewhat higher specificity than the IFN-γ production assay when Nine Mile is used as antigen stimulus. The assays showed moderate correlation: the Spearman correlation coefficient r ranged between 0.37–0.60, depending on the antigens used. Further investigation of the diagnostic potential for C. burnetii infection of both assays is warranted.

[Recurrent miscarriage turns out to be lung cancer]

BACKGROUND

If a positive pregnancy test is followed by profuse vaginal bleeding, the diagnosis of miscarriage can generally be made. Sometimes, however, elevated hCG levels may be associated with a phantom pregnancy, which may be a paraneoplastic symptom.

CASE DESCRIPTION

A 27-year-old woman was referred for a diagnosis after having experienced 3 consecutive miscarriages. The diagnostic workup could not identify an underlying cause. After 3 more biochemical miscarriages, the original diagnosis was called into question and extensive testing for ectopic hCG production was performed. It appeared that the false pregnancies were paraneoplastic symptoms of an hCG-producing non-small cell lung cancer. After a lobectomy, the hCG levels returned to normal and a spontaneous pregnancy and uncomplicated delivery followed.

CONCLUSION

Phantom pregnancy as a paraneoplastic symptom is extremely rare, but should be considered in patients presenting with recurrent, non-objectifiable miscarriages. Careful documentation of the menstrual cycle is necessary for early detection of the condition. The fact is that vaginal bleeding after a positive pregnancy test can still be a normal menstruation.

Detailed analysis of health status of Q fever patients 1 year after the first Dutch outbreak: a case-control study

BACKGROUND

Q fever is a zoonosis caused by the obligate intracellular bacterium Coxiella burnetii. The two long-term complications, after primary infection, are chronic Q fever in ∼1% of patients, and a chronic fatigue syndrome in 10-20%. However, the existence of a protracted decreased health status after Q fever remains controversial.

AIM

To determine the health status of the patients of the Q fever outbreak in The Netherlands in 2007, 1 year after primary infection.

DESIGN

Cross-sectional case-control study.

METHODS

Health status of the patients from the 2007 Dutch Q fever outbreak was compared to age-, sex- and geographically matched and Q fever seronegative controls. Health status of both patients and controls was assessed with the Nijmegen Clinical Screening Instrument (NCSI).

RESULTS

Fifty-four Q fever patients provided 34 years of age- and sex-matched controls from the same neighbourhood. Eleven controls had positive Q fever serology and were excluded. Q fever patients had significantly more problems on the subdomains of symptoms and functional impairment. Overall quality of life was decreased in both patients and controls, 59% vs. 39%, respectively, ns). Severe fatigue levels were present in 52% of patients vs. 26% in controls (P < 0.05).

CONCLUSION

These data support a sustained decrease in many aspects of health status in Q fever patients in The Netherlands, 1 year after primary infection.