Publication highlights

In this research by the Carlton and Bauer groups, the mechanisms by which SARS-CoV-2 Envelope negotiates the cell’s network of intracellular organelles was identified. By carefully placing fluorescent and enzymatic tags into the Envelope protein, the researchers identified viral sequences that allowed Envelope to move from where it is made, the Endoplasmic Reticulum, to the Golgi apparatus, where Envelope assembles with other viral proteins to make a virus particle. The researchers also identified viral sequences and host cell proteins that allowed a pool of Envelope to move from the Golgi to lysosomes, and that the presence of Envelope in lysosomes could deacidify these organelles. SARS-CoV-2 is released through the secretory pathway, and secretory lysosomes represent an atypical secretory route. Both movement of Envelope to lysosomes, and its ability to deacidify lysosomes, contribute to SARS-CoV-2 replication, giving new insight into how host cell networks can influence how the virus replicates.

Does infection or vaccination induce nasal neutralising antibodies to SARS-CoV-2 variants? The Covid Surveillance Unit has developed a fast, easy method to test if antibodies in nasal mucosa stop SARS-CoV-2 replicating in cells in swabs from participants in the UCLH-Crick Legacy study. Both vaccination and infection boosted antibody levels in nasal mucus, and repeated vaccinations could enhance this. Importantly, the range of nasal antibodies differs from that in blood, which means current vaccines may not stop infections with new antigenically different variants. The methodology used in the study will make it easy to evaluate next generation vaccines, including mucosal vaccines.

In the UCLH-Crick Legacy study, the team asked why the UK didn't experience the predicted severe COVID wave from Omicron “escape variants” XBB and B.Q.1.1 (variants which arise from weaker immune responses to the vaccine) in winter 2022, unlike Singapore and the US. They used serum collected from Legacy study volunteers and tested for neutralising antibodies against these “escape variants” before and after the bilvalent vaccine - a type of vaccine which targets the original strain and Omicron strain.

Using data from the COVID Surveillance Unit’s specialist antibody tests against variants XBB, XBB.1.5 and BQ.1.1, they found that neutralising antibodies against these variants were boosted 3-4-fold in all participants after the bivalent vaccine. They also found any prior infection was a major contributor to high levels of neutralising antibodies against these new variants, but participants who hadn’t been infected still had neutralising antibodies against XBB after vaccination. Any 4th “encounter” with another Omicron variant, Spike, in 2022, boosted antibodies against these variants in patients who had had three vaccines. People who had been infected with the BA.1/2/5 variant had similar levels of antibodies as those who had been given the 4th vaccine. In summary, the UK’s targeted 4th dose vaccine policy by JCVI complemented widespread existing hybrid immunity in the wider UK population, protecting against the predicted severe wave of COVID-19 in UK winter 2022-3.

Researchers in the Kassiotis lab have shown that a specific area of the SARS-CoV-2 spike protein is a promising target for a pan-coronavirus vaccine that could offer some protection against new virus variants, common colds, and help prepare for future pandemics.

As part of the CAPTURE study, researchers in collaboration with the National Institute for Health Research (NIHR) UCLH Biomedical Research Centre found that antibodies generated in people who had received only two doses of either the Oxford/AstraZeneca vaccine or the Pfizer/BioNTech vaccine were less able to neutralise the Omicron variant as compared to the Alpha and Delta variants. They also found that antibody levels dropped off in the first three months following the second dose but that a third ‘booster’ dose raised levels of antibodies that effectively neutralise the Omicron variant.

As part of the largest study to comprehensively evaluate the response of patients with cancer to COVID-19 vaccines, researchers in the Turajlic lab monitored the immune response of 585 patients with different types of cancer after receiving a first and second dose of the COVID-19 vaccine.
They found that patients with blood cancer were less likely to have antibodies than individuals of a similar age without cancer or with solid cancer, and when they did have antibodies, the levels were lower against all variants.

Two doses of the Oxford-AstraZeneca COVID-19 vaccine induce lower levels of antibodies that are able to recognise and fight the SARS-CoV-2 Delta variant (B.1.617.2) than against other strains.

The Legacy study team found that two doses of the Oxford-AstraZeneca vaccine generate lower levels of antibodies able to recognise the Delta variant, in comparison with the Pfizer-BioNTech vaccine. Their results also show that antibody levels vary considerably depending on likely prior infection with SARS-CoV-2.