Biology subjects

Thitithanyanont, A.

Publications and source records attributed to Thitithanyanont, A..

3 recordsLinked to original sources

bioRxiv2021

Mice immunized with the vaccine candidate HexaPro spike produce neutralizing antibodies against SARS-CoV-2

Updated and revised versions of COVID-19 vaccines are vital due to genetic variations of the SARS-CoV-2 spike antigen. Furthermore, vaccines that are safe, cost-effective, and logistically friendly are critically needed for global equity, especially for middle to low income countries. Recombinant protein-based subunit vaccines against SARS-CoV-2 have been reported with the use of the receptor binding domain (RBD) and the prefusion spike trimers (S-2P). Recently, a new version of prefusion spike trimers, so called "HexaPro", has been shown for its physical property to possess two RBD in the "up" conformation, as opposed to just one exposed RBD found in S-2P. Importantly, this HexaPro spike antigen is more stable than S-2P, raising its feasibility for global logistics and supply chain. Here, we report that the spike protein HexaPro offers a promising candidate for SARS-CoV-2 vaccine. Mice immunized by the recombinant HexaPro adjuvanted with aluminium hydroxide using a prime-boost regimen produced high-titer neutralizing antibodies for up to 56 days after initial immunization against live SARS-CoV-2 infection. In addition, the level of neutralization activity is comparable to that of convalescence sera. Our results indicate that the HexaPro subunit vaccine confers neutralization activity in sera collected from mice receiving the prime-boost regimen.

immunology↗

bioRxiv2020

Anti-SARS-CoV-2 activity of Andrographis paniculata extract and its major component Andrographolide in human lung epithelial cells and cytotoxicity evaluation in major organ cell representatives

The coronavirus disease 2019 (COVID-19) caused by a novel coronavirus (SARS-CoV-2) has become a major health problem affecting more than fifty million cases with over one million deaths globally. The effective antivirals are still lacking. Here, we optimized a high-content imaging platform and the plaque assay for viral output study using the legitimate model of human lung epithelial cells, Calu-3, to determine anti-SARS-CoV-2 activity of Andrographis paniculata extract and its major component andrographolide. SARS-CoV-2 at 25TCID50 was able to reach the maximal infectivity of 95% in Calu-3 cells. Post-infection treatment of A. paniculata and andrographolide in SARS-CoV-2 infected Calu-3 cells significantly inhibited the production of infectious virions with the IC50 of 0.036 g/mL and 0.034 M, respectively, as determined by plaque assay. The cytotoxicity profile developed over the cell line representatives of major organs, including liver (HepG2 and imHC), kidney (HK-2), intestine (Caco-2), lung (Calu-3) and brain (SH-SY5Y), showed the CC50 of >100 g/mL for A. paniculata extract and 13.2-81.5 M for andrographolide, respectively, corresponding to the selectivity index over 380. In conclusion, this study provided experimental evidence in favor of A. paniculata and andrographolide for further development as a monotherapy or in combination with other effective drugs against SARS-CoV-2 infection.

microbiology↗

bioRxiv2020

SARS-CoV-2 RNA shedding in recovered COVID-19 cases and the presence of antibodies against SARS-CoV-2 in recovered COVID-19 cases and close contacts

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). COVID-19 emerged in December 2019 and has spread globally. Although Thailand has been effective at controlling the spread of COVID-19, disease surveillance and information on antibody responses in infected cases and close contacts are needed because there is still no specific treatment or vaccine available. We investigated 217 recovered COVID-19 cases to monitor their viral RNA shedding and production of antibodies against SARS-CoV-2. The presence of antibodies in blood samples from 308 close contacts of COVID-19 cases was also determined. Viral RNA was still detectable in 6.6 % of recovered COVID-19 cases. The most prolonged duration of viral RNA shedding detected in this study was 105 days. IgM, IgG, and IgA antibodies against SARS-CoV-2 were detected in 13.82, 88.48, and 83.41 % of the recovered cases 4-12 weeks after disease onset, respectively. Although the patients had recovered from their illness, the levels of antibodies detected showed association with their symptoms during their stay in hospital. Fifteen of the 308 contacts (4.87 %) of COVID-19 cases tested positive for IgG antibodies. The presence of antibodies against SARS-CoV-2 suggested that there was viral exposure among close contacts. Viral clearance and the pattern of antibody responses in infected individuals are both crucial for effectively combatting SARS-CoV-2. Our study provides additional information on the natural history of this newly emerging disease related to both natural host defenses and a strategy for vaccine development.

immunology↗