Heterologous ChAdOx1 nCoV-19 and BNT162b2 prime-boost vaccination elicits potent neutralizing antibody responses and T cell reactivity

Heterologous COVID-19 vaccination regimens combining vector- and mRNA-based vaccines are already administered, but data on solicited adverse reactions, immunological responses and elicited protection are limited. We aimed to evaluate the reactogenicity, humoral and cellular immune responses towards different SARS-CoV-2 variants after a heterologous ChAdOx1 nCoV-19 BNT162b2 prime-boost vaccination and analyzed a cohort of 26 individuals aged 25-46 (median 30.5) years that received a ChAdOx1 nCoV-19 prime followed by a BNT162b2 boost after an 8- week interval. Self-reported solicited symptoms after ChAdOx1 nCoV-19 prime were in line with previous reports and less severe after the BNT162b2 boost. Antibody titers increased significantly over time resulting in strong neutralization titers two weeks after the BNT162b2 boost. Neutralizing activity against the prevalent strain B.1.1.7 (Alpha) and immune-evading VOC B.1.351 (Beta) was [~]4-fold higher than in individuals receiving homologous BNT162b2 vaccination. No difference was seen in neutralization of VOI B.1.617 (Kappa). In addition, the heterologous vaccination induced CD4+ and CD8+ T cells reactive to SARS-CoV-2 spike peptides of all analyzed variants; Wuhan-Hu-1, B.1.1.7, B.1.351, and P.1 (Gamma). In conclusion, heterologous ChAdOx1 nCoV-19 / BNT162b2 prime-boost vaccination regimen is not associated with serious adverse events and results in a potent humoral immune response and elicits T cell reactivity. Variants B.1.1.7, B.1.351 and B.1.617.1 are potently neutralized by sera of all participants and reactive T cells recognize spike peptides of all tested variants. These results suggest that this heterologous vaccination regimen is at least as immunogenic and protective as homologous vaccinations.

Antiviral activity of plant juices and green tea against SARS-CoV-2 and influenza virus in vitro

Many plant juices, extracts and teas have been shown to possess antiviral activity. We here analyzed the virucidal activity of black chokeberry (Aronia melanocarpa), pomegranate (Punica granatum), and elderberry (Sambucus nigra) juice, as well as green tea (Camellia sinensis) against different respiratory viruses. We found that all tested plant derived products effectively inactivated influenza virus, whereas only chokeberry juice diminished SARS-CoV-2 and vaccinia virus infectivity. None of the products inactivated non-enveloped human adenovirus type 5. Thus, black chokeberry juice exerts virucidal activity against different enveloped viral pathogens under in vitro conditions. Whether application of virucidal juices or green tea as oral rinses may lower viral loads in the oral cavity in vivo remains to be evaluated.

Systematic analysis of innate immune antagonism reveals vulnerabilities of SARS-CoV-2

The innate immune system constitutes a powerful barrier against viral infections. However, it may fail because successful emerging pathogens, like SARS-CoV-2, evolved strategies to counteract it. Here, we systematically assessed the impact of 29 SARS-CoV-2 proteins on viral sensing, type I, II and III interferon (IFN) signaling, autophagy and inflammasome formation. Mechanistic analyses show that autophagy and type I IFN responses are effectively counteracted at different levels. For example, Nsp14 induces loss of the IFN receptor, whereas ORF3a disturbs autophagy at the Golgi/endosome interface. Comparative analyses revealed that antagonism of type I IFN and autophagy is largely conserved, except that SARS-CoV-1 Nsp15 is more potent in counteracting type I IFN than its SARS-CoV-2 ortholog. Altogether, however, SARS-CoV-2 counteracts type I IFN responses and autophagy much more efficiently than type II and III IFN signaling. Consequently, the virus is relatively resistant against exogenous IFN-/{beta} and autophagy modulation but remains highly vulnerable towards IFN-{gamma} and -{lambda} treatment. In combination, IFN-{gamma} and -{lambda} act synergistically, and drastically reduce SARS-CoV-2 replication at exceedingly low doses. Our results identify ineffective type I and II antagonism as weakness of SARS-CoV-2 that may allow to devise safe and effective anti-viral therapies based on targeted innate immune activation.

IFITM proteins promote SARS-CoV-2 infection in human lung cells

Interferon-induced transmembrane proteins (IFITMs 1, 2 and 3) are thought to restrict numerous viral pathogens including severe acute respiratory syndrome coronaviruses (SARS-CoVs). However, most evidence comes from single-round pseudovirus infection studies of cells that overexpress IFITMs. Here, we verified that artificial overexpression of IFITMs blocks SARS-CoV-2 infection. Strikingly, however, endogenous IFITM expression was essential for efficient infection of genuine SARS-CoV-2 in human lung cells. Our results indicate that the SARS-CoV-2 Spike protein interacts with IFITMs and hijacks them for efficient viral entry. IFITM proteins were expressed and further induced by interferons in human lung, gut, heart and brain cells. Intriguingly, IFITM-derived peptides and targeting antibodies inhibited SARS-CoV-2 entry and replication in human lung cells, cardiomyocytes and gut organoids. Our results show that IFITM proteins are important cofactors for SARS-CoV-2 infection of human cell types representing in vivo targets for viral transmission, dissemination and pathogenesis and suitable targets for therapeutic approaches.

Alpha-1 antitrypsin inhibits SARS-CoV-2 infection

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes coronavirus disease 2019 (COVID-19). To identify factors of the respiratory tract that suppress SARS-CoV-2, we screened a peptide/protein library derived from bronchoalveolar lavage, and identified 1-antitrypsin (1-AT) as specific inhibitor of SARS-CoV-2. 1-AT targets the viral spike protein and blocks SARS-CoV-2 infection of human airway epithelium at physiological concentrations. Our findings show that endogenous 1-AT restricts SARS-CoV-2 and repurposes 1-AT-based drugs for COVID-19 therapy.

Holder Pasteurization Inactivates SARS-CoV-2 in Human Breast Milk

SARS-CoV-2 RNA has been detected in the human breast milk of infected mothers, raising concerns regarding the safety of breastfeeding upon infection. We here show that holder pasteurization inactivates SARS-CoV-2 and provides an alternative and safe option for infected mothers to continue feeding breast milk to their infants.

An enzyme-based immunodetection assay to quantify SARS-CoV-2 infection

SARS-CoV-2 is a novel pandemic coronavirus that caused a global health and economic crisis. The development of efficient drugs and vaccines against COVID-19 requires detailed knowledge about SARS-CoV-2 biology. Several techniques to detect SARS-CoV-2 infection have been established, mainly based on counting infected cells by staining plaques or foci, or by quantifying the viral genome by PCR. These methods are laborious, time-consuming and expensive and therefore not suitable for a high sample throughput or rapid diagnostics. We here report a novel enzyme-based immunodetection assay that directly quantifies the amount of de novo synthesized viral spike protein within fixed and permeabilized cells. This in-cell ELISA enables a rapid and quantitative detection of SARS-CoV-2 infection in microtiter format, regardless of the virus isolate or target cell culture. It follows the established method of performing ELISA assays and does not require expensive instrumentation. Utilization of the in-cell ELISA allows to e.g. determine TCID50 of virus stocks, antiviral efficiencies (IC50 values) of drugs or neutralizing activity of sera. Thus, the in-cell spike ELISA represents a promising alternative to study SARS-CoV-2 infection and inhibition and may facilitate future research. HighlightsO_LIDetermination of SARS-CoV-2 infection by enzymatically quantifying the expression of viral spike protein in bulk cell cultures C_LIO_LITargeting a highly conserved region in the S2 subunit of the S protein allows broad detection of several SARS-CoV-2 isolates in different cell lines C_LIO_LIScreening of antivirals in microtiter format and determining the antiviral activity as inhibitory concentrations 50 (IC50) C_LI

Remdesivir but not famotidine inhibits SARS-CoV-2 replication in human pluripotent stem cell-derived intestinal organoids

Gastrointestinal symptoms in COVID-19 are associated with prolonged symptoms and increased severity. We employed human intestinal organoids derived from pluripotent stem cells (PSC-HIOs) to analyze SARS-CoV-2 pathogenesis and to validate efficacy of specific drugs in the gut. Certain, but not all cell types in PSC-HIOs express SARS-CoV-2 entry factors ACE2 and TMPRSS2, rendering them susceptible to SARS-CoV-2 infection. Remdesivir, a promising drug to treat COVID-19, effectively suppressed SARS-CoV-2 infection of PSC-HIOs. In contrast, the histamine-2-blocker famotidine showed no effect. Thus, PSC-HIOs provide an interesting platform to study SARS-CoV-2 infection and to identify or validate drugs.

The Zinc Finger Antiviral Protein restricts SARS-CoV-2

Recent evidence shows that the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is highly sensitive to interferons (IFNs). However, the underlying antiviral effectors remain to be defined. Here, we show that Zinc finger antiviral protein (ZAP) that specifically targets CpG dinucleotides in viral RNA sequences restricts SARS-CoV-2. We demonstrate that ZAP and its cofactors KHNYN and TRIM25 are expressed in human lung cells. Type I, II and III IFNs all strongly inhibited SARS-CoV-2 and further induced ZAP expression. Strikingly, SARS-CoV-2 and its closest relatives from bats show the strongest CpG suppression among all known human and bat coronaviruses, respectively. Nevertheless, knock-down of ZAP significantly increased SARS-CoV-2 production in lung cells, particularly upon treatment with IFN- or IFN-{gamma}. Thus, our results identify ZAP as an effector of the IFN response against SARS-CoV-2, although this pandemic pathogen may be preadapted to the low CpG environment in humans. HighlightsO_LISARS-CoV-2 and its closest bat relatives show strong CpG suppression C_LIO_LIIFN-{beta}, -{gamma} and -{lambda} inhibit SARS-CoV-2 with high efficiency C_LIO_LIZAP restricts SARS-CoV-2 and contributes to the antiviral effect of IFNs C_LI

Detection of SARS-CoV-2 in Human Breast Milk

SARS-CoV-2 (CoV-2) is mainly transmitted in the human population during close contact and respiratory droplets. It is currently unclear, however, whether CoV-2 is shed into milk and may also be transmitted from infected mothers to newborns trough breast feeding. Two recent reviews on the topic (1,2) did not find evidence for CoV-2 in human milk. However, the number of breast milk samples analyzed so far is small and samples were taken only once from each mother (2).