RESUMO
The SARS-CoV-2 Omicron variant has demonstrated enhanced transmissibility and escape of vaccine-derived immunity. While current vaccines remain effective against severe disease and death, robust evidence on vaccine effectiveness (VE) against all Omicron infections (i.e. irrespective of symptoms) remains sparse. We addressed this knowledge-gap using a community-wide serosurvey with 5,310 subjects by estimating how vaccination histories modulated risk of infection in Hong Kong (which was largely infection naive) during a large wave of Omicron epidemic during January-July 2022. We estimated that Omicron infected 45% (41-48%) of the Hong Kong population. Three and four doses of BNT162b2 or CoronaVac were effective against Omicron infection (VE of 47% (95% credible interval 34-68%) and 70% (43-99%) for three and four doses of BNT162b2 respectively; VE of 31% (1-73%) and 59% (10-99%) for three and four doses of CoronaVac respectively) seven days after vaccination, but protection waned with half-lives of 15 (3-47) weeks for BNT162b2 and 5 (1-37) weeks for CoronaVac. Our findings suggest that booster vaccination can temporarily enhance population immunity ahead of anticipated waves of infections.
RESUMO
COVID-19, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which spread worldwide in 2020, is an urgent problem to be overcome. The ORF8 of SARS-CoV-2 has been suggested to be associated with the symptoms of COVID-19, according to reports of clinical studies. However, little is known about the function of ORF8. As one of the ways to advance the functional analysis of ORF8, mass production of ORF8 with the correct three-dimensional structure is necessary. In this study, we attempted to produce ORF8 protein by chemically inducible protein production system using tobacco BY-2 cells. An ORF8-producing line was generated by the Agrobacterium method. As a result, the production of ORF8 of 8.8 {+/-} 1.4 mg/L of culture medium was confirmed. SDS-PAGE and nuclear magnetic resonance (NMR) analysis confirmed that the ORF8 produced by this system is a dimeric form with a single structure, unlike that produced in Escherichia coli. Furthermore, it was suggested that the ORF8 produced by this system was glycosylated. Through this study, we succeeded in producing ORF8 folded into a single structure in a chemically inducible protein production system using tobacco BY-2 cells. It is expected that the functional analysis of ORF8 will be advanced using the ORF8 produced by this system and that it will greatly contribute to the development of antibodies and therapeutic agents targeting ORF8.
