Biology subjects

Balakrishnan, B.

Publications and source records attributed to Balakrishnan, B..

3 recordsLinked to original sources

bioRxiv2022

Surface-modified measles vaccines encoding oligomeric, fusion-stabilized SARS-CoV-2 spike glycoproteins bypass measles seropositivity, boosting neutralizing antibody responses to omicron and historical variants.

Serum titers of SARS-CoV-2 neutralizing antibodies (nAb) correlate well with protection from symptomatic COVID-19, but decay rapidly in the months following vaccination or infection. In contrast, measles-protective nAb titers are life-long after measles vaccination, possibly due to persistence of the live-attenuated virus in lymphoid tissues. We therefore sought to generate a live recombinant measles vaccine capable of driving high SARS-CoV-2 nAb responses. Since previous clinical testing of a live measles vaccine encoding a SARS-CoV-2 spike glycoprotein resulted in suboptimal anti-spike antibody titers, our new vectors were designed to encode prefusion-stabilized SARS-CoV-2 spike glycoproteins, trimerized via an inserted peptide domain and displayed on a dodecahedral miniferritin scaffold. Additionally, to circumvent the blunting of vaccine efficacy by preformed anti-measles antibodies, we extensively modified the measles surface glycoproteins. Comprehensive in vivo mouse testing demonstrated potent induction of high titer nAb in measles-immune mice and confirmed the significant incremental contributions to overall potency afforded by prefusion stabilization, trimerization, and miniferritin-display of the SARS-CoV-2 spike glycoprotein, and vaccine resurfacing. In animals primed and boosted with a MeV vaccine encoding the ancestral SARS-CoV-2 spike, high titer nAb responses against ancestral virus strains were only weakly cross-reactive with the omicron variant. However, in primed animals that were boosted with a MeV vaccine encoding the omicron BA.1 spike, antibody titers to both ancestral and omicron strains were robustly elevated and the passive transfer of serum from these animals protected K18-ACE2 mice from infection and morbidity after exposure to BA.1 and WA1/2020 strains. Our results demonstrate that antigen engineering can enable the development of potent measles-based SARS-CoV-2 vaccine candidates.

microbiology↗

bioRxiv2021

Boosting of SARS-CoV-2 immunity in nonhuman primates using an oral rhabdoviral vaccine

An orally active vaccine capable of boosting SARS-CoV-2 immune responses in previously infected or vaccinated individuals would help efforts to achieve and sustain herd immunity. Unlike mRNA-loaded lipid nanoparticles and recombinant replication-defective adenoviruses, replicating vesicular stomatitis viruses with SARS-CoV-2 spike glycoproteins (VSV-SARS2) were poorly immunogenic after intramuscular administration in clinical trials. Here, by G protein trans-complementation, we generated VSV-SARS2(+G) virions with expanded target cell tropism. Compared to parental VSV-SARS2, G-supplemented viruses were orally active in virus-naive and vaccine-primed cynomolgus macaques, powerfully boosting SARS-CoV-2 neutralizing antibody titers. Clinical testing of this oral VSV-SARS2(+G) vaccine is planned.

immunology↗

bioRxiv2021

Modulation of SARS-CoV-2 Spike-induced Unfolded Protein Response (UPR) in HEK293T cells by selected small chemical molecules

Coronaviruses (CoV) exploits the endoplasmic reticulum (ER) of the host cells for replication and in doing so, increases ER stress. evokes Unfolded Protein Response (UPR) and possibly autophagy, which could all attribute to the pathophysiology of the viral infections. To date, little is known about the roles of ER stress, UPR, and autophagy in SARS-CoV-2 infection. Here we over-expressed the viral Spike (S) protein in cultured HEK293T cells, as it has been shown that such protein is largely responsible for UPR activation in other CoV-infected cells. We noticed, in the transfected cells, heightened ER stress, activation of the PERK-eIF2 arm of the UPR, induction of autophagy and cell death. When we treated the transfected cells with Tauroursodeoxycholic acid (TUDCA), 4-phenyl butyric acid (PBA), Salubrinal, Trazadone hydrochloride, and Dibenzoylmethane (DBM), we saw reduced the BiP/GRP78 levels, but only PBA and TUDCA could significantly diminish the levels of peIF2 and autophagy expression.

biochemistry↗