Studying temporal titre evolution of commercial SARS-CoV-2 assays reveals significant shortcomings of using BAU standardization for comparison.

BACKGROUND: Measuring specific anti-SARS-CoV-2 antibodies has become one of the main epidemiological tools to survey the ongoing SARS-CoV-2 pandemic, but also vaccination response. The WHO made available a set of well-characterized samples derived from recovered individuals to allow normalization between different quantitative anti-Spike assays to defined Binding Antibody Units (BAU). METHODS: To assess sero-responses longitudinally, a cohort of ninety-nine SARS-CoV-2 RT-PCR positive subjects was followed up together with forty-five vaccinees without previous infection but with two vaccinations. Sero-responses were evaluated using a total of six different assays: four measuring anti-Spike proteins (converted to BAU), one measuring anti-Nucleocapsid proteins and one SARS-CoV-2 surrogate virus neutralization. Both cohorts were evaluated using the Euroimmun Anti-SARS-CoV-2-ELISA anti-S1 IgG and the Roche Elecsys Anti-SARS-CoV-2 anti-S1 assay. RESULTS: In SARS-CoV-2-convalesce subjects, the BAU-sero-responses of Euroimmun Anti-SARS-CoV-2-ELISA anti-S1 IgG and Roche Elecsys Anti-SARS-CoV-2 anti-S1 peaked both at 47 (43-51) days, the first assay followed by a slow decay thereafter (> 208 days), while the second assay not presenting any decay within one year. Both assay values in BAUs are only equivalent a few months after infection, elsewhere correction factors up to 10 are necessary. In contrast, in infection-naive vaccinees the assays perform similarly. CONCLUSION: The results of our study suggest that the establishment of a protective correlate or vaccination booster recommendation based on different assays, although BAU-standardised, is still challenging. At the moment the characteristics of the available assays used are not related, and the BAU-standardisation is unable to correct for that.

Detection of HIV-1 subtypes, recombinants, and dual infections in east Africa by a multi-region hybridization assay.

OBJECTIVE: To enable more rapid and efficient genotyping of HIV-1 in East Africa, where subtypes A, C, and D and their recombinants are co-circulating. DESIGN: Full-genome sequencing of HIV-1 provides complete discrimination of subtypes and recombinant forms but is costly and low-throughput compared to other genotyping approaches. Here we describe the development and evaluation of a Multi-region Hybridization Assay (MHA) for the efficient determination of HIV-1 subtypes A, C, D, recombinants, and dual infections. METHODS: Five genome regions containing clustered mutations distinguishing subtypes A, C, and D were identified and used to design subtype-specific probes. DNA from primary peripheral blood mononuclear cells was used as template for real-time PCR using the fluorescent, subtype-specific probes. RESULTS: A panel of 45 clinical samples from Uganda, Kenya, and Tanzania, previously characterized by full-genome sequencing and including 26 pure subtypes and 19 recombinant strains, was evaluated by MHA. The MHA provided 90% sensitivity and 98% specificity for the three subtypes, efficiently discriminated subtypes from recombinant forms, and detected several dual infections. CONCLUSIONS: Accurate and efficient genotyping of HIV-1 strains in vaccine trial populations in East Africa, ascertainment of dual infections, and elucidation of the genesis of recombinant forms in individuals can be facilitated by the application of MHA.

First detection of the microsporidium Enterocytozoon bieneusi in non-mammalian hosts (chickens).

Faecal samples taken from eight underweight, approximately 5-week-old broiler chickens in a poultry abattoir were investigated for microsporidial infections by light microscopy, electron microscopy, and PCR. In two of six chickens, which were suspected of being infected with microsporidia by light microscopy, Enterocytozoon bieneusi (genotype 'J') was detected by PCR and DNA sequencing, and in one of the two PCR-positive samples by extensive electron microscopy. This is the first time that E. bieneusi has been detected in chickens, i.e. in a non-mammalian species.

Disseminated lethal Encephalitozoon cuniculi (genotype III) infections in cotton-top tamarins (Oedipomidas oedipus)--a case report.

For the first time, Encephalitozoon (E.) cuniculi genotype III ('dog strain') was verified in two cotton-top tamarins (Oedipomidas oedipus) by light microscopy, immunohistochemistry, electron microscopy, PCR and sequencing. The animals had a disseminated lethal infection with this protist. In earlier reports, genotype III had been found only in domestic dogs, man, emperor tamarins (Saguinus imperator) and golden lion tamarins (Leontopithecus rosalia). This investigation establishes now that the 'dog strain' can occur in cotton-top tamarins too. This is further evidence for the zoonotic potential of E. cuniculi. Furthermore, free E. cuniculi spores were identified also in blood vessels of several tissues. These findings indicate that during a disseminated infection E. cuniculi spores can occur in peripheral blood, too. We propose that blood should also be included in the investigations for the detection of microsporidia, so that a possible disseminated course of an infection can be detected.