This week’s Research Tracker has a focus on antibodies - their persistence and therapeutic uses. There are also articles on plasma shifts, vaccination challenges, bat resistance, and viral mimicry.
The Research Tracker is prepared by Dr Robert Hickson for the Science Media Centre.
Waning antibodies?
A paper from Imperial College London, released as a pre-print, describes declining prevalence of IgG antibodies against SARS-CoV-2 over three months. The authors suggest that this may indicate declining immunity.
Interpretations of the results have been challenged by other researchers. Antibody levels do decline over time, but memory B cells can rapidly produce antibodies if a re-infection occurs. And, other studies demonstrate longer or more stable antibody persistence.
Evidence for longer lasting antibodies
A paper in Immunity describes detecting antibodies seven months after infection.
A paper in Science reports detecting relatively stable antibody levels over five months, and good virus neutralising activity.
A study, published in Science Immunology, found that IgG antibody levels in patients with severe Covid-19 declined only slowly over three months.
We have previously covered this theme in the 21 August and 25 September editions.
Autoimmune responses to antibodies
A study, not yet peer reviewed and based on only 31 patients, found that patients critically ill with Covid-19 reacted against their own antibodies. The authors infer that disease progression leads to autoimmune reactions, rather than vice versa.
Antibody therapies
A news article in Nature discusses antibody therapies currently in clinical trials. Such therapies may help prevent progression to more severe disease, rather than being effective at treating severe Covid-19. The article notes that antibodies are difficult and expensive to make.
Interim analyses of a Phase 2 clinical trial of a monoclonal antibody therapy have been published in the New England Journal of Medicine. Patients with early stage disease were given one of three doses of the antibody and evaluated after 11 days.
The results weren’t remarkable. Only those receiving the middle level dose had lower viral levels, compared with patients receiving a placebo. All monoclonal antibody treatments led to only modest improvements in symptoms. There were no serious adverse effects.
Major differences in plasma profiles between mild and moderate Covid-19 disease states
An impressive study, published in Cell, examines cell types, molecules and metabolites in the plasma of patients with different degrees of Covid-19 severity. There is a marked difference in plasma conditions between patients with mild and moderate disease.
This signals a shift to a more stressed plasma environment, with lower metabolic resources and greater abundance of pro-inflammatory cells and molecules in the moderate disease state.
What causes the change is unclear at present. The findings, though, suggest some useful biomarkers to monitor disease progression.
Answering “Does this Covid-19 vaccine work?” is hard
A paper in The Lancet Infectious Diseases notes that Phase 3 clinical trials do not allow a good assessment of how well a vaccine protects against severe illness and death. This can be determined only after wide scale vaccination. Challenges in determining vaccine effectiveness are reviewed. It emphasises the need for well designed studies that measure vaccine efficacy in several ways.
Communications about, and logistics of, vaccinations may define 2021
An editorial in Nature Biotechnology highlights the importance of clear and consistent communications about vaccines to build trust and manage expectations. This hasn’t been the case for public health messaging so far in many countries.
Public expectations for the efficacy of a vaccine may be unrealistically high, and significant proportions of populations have indicated that they will not be vaccinated. The editorial suggests that global distribution of the vaccine(s) will be the defining public health challenge next year.
To the bat genome
A study published in Proceedings of the National Academy of Sciences (only the abstract is free to view) explores why bats can have high, and diverse, viral levels but few clinical symptoms. It found a variety of genetic changes lead to reduced hyper-inflammatory immune responses following infections. This limits tissue damage and disease. The findings may help develop new therapeutics for humans.
Imitation is the surest form of infectivity
An interesting study in Cell Systems compared the protein structures of nearly 7,500 viruses, including coronaviruses, to determine the extent to which they “mimic” other viral or host proteins. The authors conclude that mimicry is a common viral strategy, with structural similarity enabling viral proteins to utilise host metabolic pathways.