Biology subjects

Kurhade, C.

Publications and source records attributed to Kurhade, C..

7 recordsLinked to original sources

bioRxiv2022

Neutralization of Omicron sublineages and Deltacron SARS-CoV-2 by 3 doses of BNT162b2 vaccine or BA.1 infection

Distinct SARS-CoV-2 Omicron sublineages have evolved showing increased fitness and immune evasion than the original Omicron variant BA.1. Here we report the neutralization activity of sera from BNT162b2 vaccinated individuals or unimmunized Omicron BA.1-infected individuals against Omicron sublineages and "Deltacron" variant (XD). BNT162b2 post-dose 3 immune sera neutralized USA-WA1/2020, Omicron BA.1-, BA.2-, BA.2.12.1-, BA.3-, BA.4/5-, and XD-spike SARS-CoV-2s with geometric mean titers (GMTs) of 1335, 393, 298, 315, 216, 103, and 301, respectively; thus, BA.4/5 SARS-CoV-2 spike variant showed the highest propensity to evade vaccine neutralization compared to the original Omicron variants BA.1. BA.1-convalescent sera neutralized USA-WA1/2020, BA.1-, BA.2-, BA.2.12.1-, BA.3-, BA.4/5-, and Deltacron-spike SARS-CoV-2s with GMTs of 15, 430, 110, 109, 102, 25, and 284, respectively. The low neutralization titers of vaccinated sera or convalescent sera from BA. 1 infected individuals against the emerging and rapidly spreading Omicron BA.4/5 variants provide important results for consideration in the selection of an updated vaccine in the current Omicron wave.

microbiology↗

bioRxiv2022

Cross neutralization of Omicron BA.1 against BA.2 and BA.3 SARS-CoV-2

The Omicron SARS-CoV-2 has three distinct sublineages, among which sublineage BA.1 is responsible for the initial Omicron surge and is now being replaced by BA.2 world-wide, whereas BA.3 is currently at a low frequency. The ongoing BA.1-to-BA.2 replacement underscores the importance to understand the cross-neutralization among the three Omicron sublineages. Here we tested the neutralization of BA.1-infected human sera against BA.2, BA.3, and USA/WA1-2020 (a strain isolated in late January 2020). The BA.1-infected sera neutralized BA.1, BA.2, BA.3, and USA/WA1-2020 SARS-CoV-2s with geometric mean titers (GMTs) of 445, 107, 102, and 16, respectively. Thus, the neutralizing GMTs against heterologous BA.2, BA.3, and USA/WA1-2020 were 4.2-, 4.4-, and 28.4-fold lower than the GMT against homologous BA.1, respectively. These findings have implications in COVID-19 vaccine strategy.

microbiology↗

bioRxiv2022

Neutralization of Omicron BA.1, BA.2, and BA.3 SARS-CoV-2 by 3 doses of BNT162b2 vaccine

The newly emerged Omicron SARS-CoV-2 has 3 distinct sublineages: BA.1, BA.2, and BA.3. BA.1 accounts for the initial surge and is being replaced by BA.2, whereas BA.3 is at a low prevalence at this time. Here we report the neutralization of BNT162b2-vaccinated sera (collected at 1 month after dose 3) against the three Omicron sublineages. To facilitate the neutralization testing, we engineered the complete BA.1, BA.2, or BA.3 spike into an mNeonGreen USA-WA1/2020 SRAS-CoV-2. All BNT162b2-vaccinated sera neutralized USA-WA1/2020, BA.1-, BA.2-, and BA.3-spike SARS-CoV-2s with titers of >20; the neutralization geometric mean titers (GMTs) against the four viruses were 1211, 336, 300, and 190, respectively. Thus, the BA.1-, BA.2-, and BA.3-spike SARS-CoV-2s were 3.6-, 4.0-, and 6.4-fold less efficiently neutralized than the USA-WA1/2020, respectively. Our data have implications in vaccine strategy and understanding the biology of Omicron sublineages.

microbiology↗

bioRxiv2022

A live-attenuated SARS-CoV-2 vaccine candidate with accessory protein deletions

We report a live-attenuated SARS-CoV-2 vaccine candidate with (i) re-engineered viral transcriptional regulator sequences and (ii) deleted open-reading-frames (ORF) 3, 6, 7, and 8 ({Delta}3678). The {Delta}3678 virus replicates about 7,500-fold lower than wild-type SARS-CoV-2 on primary human airway cultures, but restores its replication on interferon-deficient Vero-E6 cells that are approved for vaccine production. The {Delta}3678 virus is highly attenuated in both hamster and K18-hACE2 mouse models. A single-dose immunization of the {Delta}3678 virus protects hamsters from wild-type virus challenge and transmission. Among the deleted ORFs in the {Delta}3678 virus, ORF3a accounts for the most attenuation through antagonizing STAT1 phosphorylation during type-I interferon signaling. We also developed an mNeonGreen reporter {Delta}3678 virus for high-throughput neutralization and antiviral testing. Altogether, the results suggest that {Delta}3678 SARS-CoV-2 may serve as a live-attenuated vaccine candidate and a research tool for potential biosafety level-2 use.

microbiology↗

bioRxiv2022

Remdesivir and GS-441524 retain antiviral activity against Delta, Omicron, and other emergent SARS-CoV-2 variants

Genetic variation of SARS-CoV-2 has resulted in the emergence and rapid spread of multiple variants throughout the pandemic, of which Omicron is currently the predominant variant circulating worldwide. SARS-CoV-2 variants of concern or interest (VOC/VOI) have evidence of increased viral transmission, disease severity, or decreased effectiveness of vaccines and neutralizing antibodies. Remdesivir (RDV, VEKLURY(R)) is a nucleoside analog prodrug and the first FDA-approved antiviral treatment of COVID-19. Here we present a comprehensive antiviral activity assessment of RDV and its parent nucleoside, GS-441524, against 10 current and former SARS-CoV-2 VOC/VOI clinical isolates by nucleoprotein ELISA and plaque reduction assay. Delta and Omicron variants remained susceptible to RDV and GS-441524, with EC50 values 0.31 to 0.62-fold of those observed against the ancestral WA1 isolate. All other tested variants exhibited EC50 values ranging from 0.15 to 2.3-fold of the observed EC50 values against WA1. Analysis of nearly 6 million publicly available variant isolate sequences confirmed that Nsp12, the RNA-dependent RNA polymerase (RdRp) target of RDV and GS-441524, is highly conserved across variants with only 2 prevalent changes (P323L and G671S). Using recombinant viruses, both RDV and GS-441524 retained potency against all viruses containing frequent variant substitutions or their combination. Taken together, these results highlight the conserved nature of SARS-CoV-2 Nsp12 and provide evidence of sustained SARS-CoV-2 antiviral activity of RDV and GS-441524 across the tested variants. The observed pan-variant activity of RDV supports its continued use for the treatment of COVID-19 regardless of the SARS-CoV-2 variant.

microbiology↗

bioRxiv2022

Neutralization of Omicron SARS-CoV-2 by 2 or 3 doses of BNT162b2 vaccine

We report the antibody neutralization against Omicron SARS-CoV-2 after 2 and 3 doses of BNT162b2 mRNA vaccine. Vaccinated individuals were serially tested for their neutralization against wild-type SARS-CoV-2 (strain USA-WA1/2020) and an engineered USA-WA1/2020 bearing the Omicron spike glycoprotein. Plaque reduction neutralization results showed that at 2 or 4 weeks post-dose-2, the neutralization geometric mean titers (GMTs) were 511 and 20 against the wild-type and Omicron-spike viruses, respectively, suggesting that two doses of BNT162b2 were not sufficient to elicit robust neutralization against Omicron; at 1 month post-dose-3, the neutralization GMTs increased to 1342 and 336, respectively, indicating that three doses of vaccine increased the magnitude and breadth of neutralization against Omicron; at 4 months post-dose-3, the neutralization GMTs decreased to 820 and 171, respectively, suggesting similar neutralization decay kinetics for both variants. The data support a three-dose vaccine strategy and provide the first glimpse of the neutralization durability against Omicron.

microbiology↗

bioRxiv2021

Neutralization against Omicron SARS-CoV-2 from previous non-Omicron infection

The explosive spread of the Omicron SARS-CoV-2 variant underscores the importance of analyzing the cross-protection from previous non-Omicron infection. We developed a high-throughput neutralization assay for Omicron SARS-CoV-2 by engineering the Omicron spike gene into an mNeonGreen USA-WA1/2020 SARS-CoV-2 (isolated in January 2020). Using this assay, we determined the neutralization titers of patient sera collected at 1- or 6-months after infection with non-Omicron SARS-CoV-2. From 1- to 6-month post-infection, the neutralization titers against USA-WA1/2020 decreased from 601 to 142 (a 4.2-fold reduction), while the neutralization titers against Omicron-spike SARS-CoV-2 remained low at 38 and 32, respectively. Thus, at 1- and 6-months after non-Omicron SARS-CoV-2 infection, the neutralization titers against Omicron were 15.8- and 4.4-fold lower than those against USA-WA1/2020, respectively. The low cross-neutralization against Omicron from previous non-Omicron infection supports vaccination of formerly infected individuals to mitigate the health impact of the ongoing Omicron surge.

microbiology↗