Mahasirimongkol, S. | Search bioRxiv

bioRxiv2022

The humoral and cellular immune response of a third dose adenoviral-based vectored vaccine after a single or 2 shots of inactivated COVID-19 vaccine in healthy adults.

The coronavirus pandemic is a severe infectious respiratory disease which caused massive loss worldwide. Thailand was affected by the wild-type, and the Delta variant started in mid-2021. Due to the shortage of effective vaccines, the ministry of public health of Thailand suggested the heterologous vaccine scheme, which comprises inactivated COVID-19 vaccine (CoronaVac) and an adenoviral-based vectored vaccine (ChAdOx1). However, data on the humoral and cellular immune responses of the single or 2 shots of inactivated vaccine followed by the adenoviral-based vaccine are very limited. In this current study, the sera from participants who received either single or 2 shots of CoronaVac followed by the ChAdOx1 vaccine were evaluated for SARS-CoV-2 spike receptor-binding-domain (RBD) IgG. The cytokine level was also assessed using Luminex immunoassay. The PBMC were collected to evaluate spike-specific T-cell and B-cell responses. Participants who received 2 shots of CoronaVac followed by ChAdOx1 possessed significantly (P<0.0001) higher levels of spike RBD-specific IgG. They also exhibited a higher level of CD4+T-cell and IFN-gamma than those who received only 1 shot of CoronaVac followed by the ChAdOx1 vaccine. The volunteers who received two shots of CoronaVac followed by ChAdOx1 had a significantly (p<0.01) higher marginal B-cell response against wild-type SARS-CoV-2 S peptides than those who received only one shot of CoronaVac followed by ChAdOx1. Surprisingly, the class switch B-cell response to Delta variant SARS-CoV-2 S peptides of the volunteers who received 1 shot of CoronaVac followed by ChAdOx1 was significantly (p<0.01) higher than those who received 2 shots of CoronaVac. However, participants who received only a single shot of inactivated vaccine followed by an adenoviral-based vectored vaccine possessed a higher level of TNF-alpha and IL-6. This study indicated that boosting the ChAdOx1 as a third dose after completing 2 shots of CoronaVac induced strong humoral and cellular immune responses.

immunology↗

bioRxiv2020

Local adaptation in populations of Mycobacterium tuberculosis endemic to the Indian Ocean Rim

Lineage 1 (L1) and 3 (L3) are two lineages of the Mycobacterium tuberculosis complex (MTBC), causing tuberculosis (TB) in humans. L1 and L3 are endemic to the Rim of the Indian Ocean, the region that accounts for most of the worlds new TB cases. Despite their relevance for this region, L1 and L3 remain understudied. Here we analyzed 2,938 L1 and 2,030 L3 whole genome sequences originating from 69 countries. We show that South Asia played a central role in the dispersion of these two lineages to neighboring regions. Moreover, we found that L1 exhibits signatures of local adaptation at the esxH locus, a gene coding for a secreted effector that targets the human endosomal sorting complex, and is included in several vaccine candidates. Our study highlights the importance of genetic diversity in the MTBC, and sheds new light on two of the most important MTBC lineages affecting humans.

genomics↗