Broad spectrum post-entry inhibitors of coronavirus replication: Cardiotonic steroids and monensin

A small molecule screen identified several cardiotonic steroids (digitoxin and ouabain) and the ionophore monensin as potent inhibitors of HCoV-229E, HCoV-OC43, and SARS-CoV-2 replication with EC50s in the low nM range. Subsequent tests confirmed antiviral activity in primary cell models including human nasal epithelial cells and lung organoids. Addition of digitoxin, ouabain, or monensin strongly reduced viral gene expression as measured by both viral protein and RNA accumulation. Furthermore, the compounds acted post virus entry. While the antiviral activity of digitoxin was dependent upon activation of the MEK and JNK signaling pathways but not signaling through GPCRs, the antiviral effect of monensin was reversed upon inhibition of several signaling pathways. Together, the data demonstrates the potent anti-coronavirus properties of two classes of FDA approved drugs that function by altering the properties of the infected cell, rendering it unable to support virus replication.

On a path toward a broad-spectrum anti-viral: inhibition of HIV-1 and coronavirus replication by SR kinase inhibitor harmine

IMPORTANCE

This study highlights the crucial role RNA processing plays in regulating viral gene expression and replication. By targeting SR kinases, we identified harmine as a potent inhibitor of HIV-1 as well as coronavirus (HCoV-229E and multiple SARS-CoV-2 variants) replication. Harmine inhibits HIV-1 protein expression and reduces accumulation of HIV-1 RNAs in both cell lines and primary CD4+ T cells. Harmine also suppresses coronavirus replication post-viral entry by preferentially reducing coronavirus sub-genomic RNA accumulation. By focusing on host factors rather than viral targets, our study offers a novel approach to combating viral infections that is effective against a range of unrelated viruses. Moreover, at doses required to inhibit virus replication, harmine had limited toxicity and minimal effect on the host transcriptome. These findings support the viability of targeting host cellular processes as a means of developing broad-spectrum anti-virals.

P–404 Low serum progesterone on the day of frozen blastocyst transfer is associated with a diminished ongoing pregnancy rate in hormonal replacement therapy cycles

Study question

Is there a relationship between progesterone levels on the day of frozen blastocyst transfer and ongoing pregnancy rate (OPR), in hormonal replacement therapy (HRT) cycles?

Summary answer

Women undergoing HRT-frozen embryo transfer with progesterone levels≤9.76ng/ml on the day of blastocyst transfer had a significantly lower OPR than those with progesterone levels>9.76 ng/ml.

What is known already

The importance of serum progesterone levels around the time of frozen embryo transfer (FET) is a burning issue, in view of the growing number of FET worldwide. However, the optimal range of serum progesterone levels is not clearly determined and discrepancies arise from the current literature. Study design, size, duration: Observational cohort study with 915 patients undergoing HRT-FET at a tertiary care university hospital, between January 2019 and March 2020.

Participants/materials, setting, methods

Patients undergoing single autologous blastocyst FET under HRT using exogenous estradiol and vaginal micronized progesterone for endometrial preparation. Women were only included once during the study period. The serum progesterone level was measured in the morning of the FET, in a single laboratory. The primary endpoint was OPR beyond pregnancy week 12. Statistical analysis was conducted using univariate and multivariate logistic regression models.

Main results and the role of chance

Mean serum progesterone level on the day of FET was 12.90 ± 4.89 ng/ml). The OPR was 35.5% (325/915) in the overall population. Patients with a progesterone level ≤ 25th percentile (≤9.76ng/ml) had a significantly lower OPR and a higher miscarriage rate (MR) compared with women with progesterone level over Centile 25 (29.6% versus 37.4%; p = 0.033 and 34.8% versus 21.3%; p = 0.008, respectively). After adjustment for the potential confounders in a multivariate analysis, a serum progesterone level ≤ 9.76 ng/ml on the day of FETand FET of a Day 6-blastocyst (versus Day 5-blastocyst) were found as independent risks factor of lower OPR.

Limitations, reasons for caution

The main limitation of our study is linked to its observational design. Extrapolation of our results to other laboratories, or other routes and/or doses of administering progesterone also needs to be validated.

Wider implications of the findings: This study suggests that a minimum serum progesterone level is needed to optimize reproductive outcomes in autologous blastocyst FET, in HRT-cycles. Further studies are needed to evaluate if modifications of progesterone routes and/or doses may improve pregnancy chances, in an approach to individualize the management of ART patients.

Trial registration number

NA