Two elementary parameters for quantifying viral infection and shedding are viral load and whether samples yield a replicating virus isolate in cell culture. We examined 25,381 German SARS-CoV-2 cases, including 6110 from test centres attended by pre-symptomatic, asymptomatic, and mildly-symptomatic (PAMS) subjects, 9519 who were hospitalised, and 1533 B.1.1.7 lineage infections. The youngest had mean log10 viral load 0.5 (or less) lower than older subjects and an estimated ~78% of the peak cell culture replication probability, due in part to smaller swab sizes and unlikely to be clinically relevant. Viral loads above 109 copies per swab were found in 8% of subjects, one-third of whom were PAMS, with mean age 37.6. We estimate 4.3 days from onset of shedding to peak viral load (8.1) and cell culture isolation probability (0.75). B.1.1.7 subjects had mean log10 viral load 1.05 higher than non-B.1.1.7, with estimated cell culture replication probability 2.6 times higher.

Background Antigen point-of-care tests (AgPOCTs) can accelerate SARS-CoV-2 testing. As some AgPOCTs have become available, interest is growing in their utility and performance. Here we aimed to compare the analytical sensitivity and specificity of seven commercially available AgPOCT devices. Methods In a single-centre, laboratory evaluation study, we compared AgPOCT products from seven suppliers: the Abbott Panbio COVID-19 Ag Rapid Test, the RapiGEN BIOCREDIT COVID-19 Ag, the Healgen Coronavirus Ag Rapid Test Cassette (Swab), the Coris BioConcept COVID-19 Ag Respi-Strip, the R-Biopharm RIDA QUICK SARS-CoV-2 Antigen, the nal von minden NADAL COVID-19 Ag Test, and the Roche-SD Biosensor SARS-CoV Rapid Antigen Test. Tests were evaluated on recombinant SARS-CoV-2 nucleoprotein, cultured endemic and emerging coronaviruses, stored respiratory samples with known SARS-CoV-2 viral loads, stored samples from patients with respiratory pathogens other than SARS-CoV-2, and self-sampled swabs from healthy volunteers. We estimated analytical sensitivity in terms of approximate viral concentrations (quantified by real-time RT-PCR) that yielded positive AgPOCT results, and specificity in terms of propensity to generate false-positive results. Findings In 138 clinical samples with quantified SARS-CoV-2 viral load, the 95% limit of detection (concentration at which 95% of test results were positive) in six of seven AgPOCT products ranged between 2·07 × 10 6 and 2·86 × 10 7 copies per swab, with an outlier (RapiGEN) at 1·57 × 10 10 copies per swab. The assays showed no cross-reactivity towards cell culture or tissue culture supernatants containing any of the four endemic human coronaviruses (HCoV‑229E, HCoV‑NL63, HCoV‑OC43, or HCoV‑HKU1) or MERS-CoV, with the exception of the Healgen assay in one repeat test on HCoV-HKU1 supernatant. SARS-CoV was cross-detected by all assays. Cumulative specificities among stored clinical samples with non-SARS-CoV-2 infections (n=100) and self-samples from healthy volunteers (n=35; cumulative sample n=135) ranged between 98·5% (95% CI 94·2–99·7) and 100·0% (97·2–100·0) in five products, with two outliers at 94·8% (89·2–97·7; R-Biopharm) and 88·9% (82·1–93·4; Healgen). False-positive results did not appear to be associated with any specific respiratory pathogen. Interpretation The sensitivity range of most AgPOCTs overlaps with SARS-CoV-2 viral loads typically observed in the first week of symptoms, which marks the infectious period in most patients. The AgPOCTs with limit of detections that approximate virus concentrations at which patients are infectious might enable shortcuts in decision making in various areas of health care and public health. Funding EU's Horizon 2020 research and innovation programme, German Ministry of Research, German Federal Ministry for Economic Affairs and Energy...

PB1-F2 is a pro-apoptotic polypeptide of many influenza A virus (FLUAV) isolates encoded by an alternative ORF of segment 2. A comprehensive GenBank search was conducted to analyse its prevalence. This search yielded 2226 entries of 80 FLUAV subtypes. Of these sequences, 87 % encode a PB1-F2 polypeptide greater than 78 aa. However, classic swine influenza viruses and human H1N1 isolates collected since 1950 harbour a truncated PB1-F2 sequence. While PB1-F2 of human H1N1 viruses terminates after 57 aa, classic swine H1N1 sequences have in-frame stop codons after 11, 25 and 34 codons. Of the avian sequences, 96 % encode a full-length PB1-F2. One genetic lineage of segment 2 sequences which is avian-like and different from the classic swine FLUAV comprises PB1-F2 sequences of porcine FLUAVs isolated in Europe (H1N1, H1N2, H3N2). Of these PB1-F2 sequences, 42 % also exhibit stop codons after 11, 25 and 34 codons. These amino acid positions are highly conserved among all FLUAV isolates irrespective of their origin. Molecular genetic analyses reveal that PB1-F2 is under constraint of the PB1 gene. The PB1-F2 polypeptide of FLUAVs isolated from European pigs is expressed in host cells as demonstrated by immunohistochemistry. Using different PB1-F2 versions fused to an enhanced GFP, mitochondrial localization is demonstrated for those PB1-F2 polypeptides which are greater than 78 aa while a truncated version (57 aa) shows a diffuse cytoplasmic distribution. This indicates similar properties and function of porcine and human FLUAV PB1-F2.

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A 42-year-old female patient with acute myeloid leukemia presented with fever and heavy chest pain after her first cycle of specific chemotherapy. Acute myocardial infarction was excluded, but surprisingly, parasitic inclusions in erythrocytes became obvious in Pappenheim and Giemsa-stained peripheral blood smears. The patient did not remember a tick bite but acknowledged having received several blood transfusions in her recent medical history. Suspicion of malaria was ruled out by use of a dip-stick test. The diagnosis of Babesia microti infection was finally established by specific polymerase chain reaction (PCR). Six weeks after initiation of specific treatment, PCR turned negative and a positive immunoflourescence assay (IFA) with an IgG titer of 1:128 indicated seroconversion. Subsequent screening of donors involved in the transfusion of blood products to the patient demonstrated borderline reactivity for Babesia microti (IgG-titer 1:32) in 1 out of 44 individuals. Neither the patient nor the positively tested blood donor had travelled to North America or Asia. Therefore, this is the first confirmed autochthonous human infection in Europe.