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Testing antibody levels using saliva

by David Wraith | 9 months ago | in Low volume blood collection and sample elution for serology testing
B: One to watch

https://www.birmingham.ac.uk/news/latest/2020...-diagnosis.aspx Working closely with The Binding Site we have developed a highly sensitive test for COVID-19 antibodies. This gives positive results within 3d post-symptoms and in convalescent sera. Importantly, the test detects antibodies in saliva. We propose that a saliva test would be easier, less invasive and more relevant for detection of the protective antibodies in this respiratory disease.

Have you validated this method, if so, how and what were the results of the validation?​

This is underway. Saliva gives weaker responses than sera but is being validates against sera at present. We have access to longitudinal samples, with matching sera to validate the results.

How quickly could this be deployed and what are the dependencies?​

Our assay for blood samples is already in place and being used to test Health Care Workers in the Birmingham region. Our assay for saliva will be ready and validated within 2-3 weeks.

What is the likely production volume?​

We are working with The Binding Site who have produced and delivered up to 20M free light chain tests in collaboration with our Clinical Immunology Service in the last year alone.

What are the risks and barriers to using this at scale?​

We have ample supplies of detection antibodies since there were generated and are banked in our Clinical Immunology Service laboratories. We are also able to generate >10mg quantities of the detection antigen in our own Protein Expression Facility. We are confident that working with the Binding Site, we could test up to 1M samples per week. The Binding Site can produce dried plates to ship to other laboratories for scale up.

Who are you already partnering with on this?

The Binding Site (Birmingham)

How does this fit into a tracked sample pathway?

The Binding Site provides dried plates that are transported to the Clinical Immunology Service at the University of Birmingham for screeing serum and saliva samples from patients, health care workers and the general population.

David Wraith

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Sue Hill 9 months ago

will the validation in saliva be compared to results from whole blood ? can you provide some information about the COVID 19 target antigen/s ?

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David Wraith 9 months ago

We are comparing both blood and saliva for validation. We have test the receptor binding domain, whole Spike protein and nucleocapsid protein as antigens. At this time we would favour the native Spike protein with the correct conformation and glycosylation

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Sue Hill 9 months ago

given this challenge is about how to get the sample, what have you developed to potentially collect the saliva in the community ?

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David Wraith 9 months ago

We have collected saliva in sterile tubes making this easy for the donor. Deposition on filter paper would also work.

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Bev Matthews 9 months ago

Status label added: C

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Lawrence Young 9 months ago

Does this test specifically identify IgA antibodies? IgA antibodies have already been found early in the blood of some COVID-19 patients with mild symptoms -see attached. Previous experimental studies with SARS-CoV-1 in mice suggest that nasal administration of a vaccine is more effective that i.v. or i.m. So mucosal immunity important.

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David Wraith 9 months ago

Lawrence, I couldn't agree more. We must measure IgA in saliva since, as you know, the ratio of different IgA isotypes differs between saliva and blood. We will identify the appropriate correlate of immune protection and then test for this in the population. As you know, the clinical immunology laboratory in Birmingham is well complete this efficiently.

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Samuel Moses 8 months ago

Dear David, Alex: is the assay now available for other sites to use?

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Samuel Moses 8 months ago

This will be really useful to have. Are you working with Alex Richter at Birmingham, who I have been in touch with regarding saliva testing; as here we are looking to initiate a staff antibody surveillance programme

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David Wraith 8 months ago

Yes Samuel, I am supporting work in the Clinical Immunology Service in Birmingham led by Alex Richter with Mark Drayson and a host of immunologist, virologists and other experts. Importantly, we are also working on this with The Binding Site in Birmingham so as to have our tests available as soon as possible.

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Bev Matthews 8 months ago

The idea has been progressed to the next milestone.

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Bev Matthews 8 months ago

hello David, is there a rough order of magnitude difference between saliva and blood?

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David Wraith 8 months ago

From the paired analysis that we have done using a titration of serum and saliva there is approximately 30x more antibody in serum than saliva. However, saliva samples give a low background which means that it is equally possible to detect +ve individuals in convalescent samples from people who have had a mild infection.

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Bev Matthews 8 months ago

Status label added: Requires more information

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Bev Matthews 7 months ago

Hello David, your solution has been reviewed and the champions would like to hear more when you have additional information to share. The follow-up team will be in contact early next week. Many thanks Bev

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David Wraith 7 months ago

Thank you Bev, we now have extensive data comparing serum with saliva. Saliva has been used for both antigen and antibody testing with excellent results. I look forward to hearing from the follow-up team early next week.

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Bev Matthews 7 months ago

Status label added: B: One to watch

Status labels removed: C: Further assessment, More information requested

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Bev Matthews 7 months ago

The idea has been progressed to the next milestone.

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David Wraith 7 months ago

Hi Bev, it would be good to know what happens next. Looking forward to discussing this further and also telling you about our comparison of saliva with dried blood spots.

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Bev Matthews 7 months ago

Thank you David, our review team will be in contact, please do share any additional information. Thanks Bev

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David Wraith 6 months ago

Bev, 3 weeks ago you said that "your solution has been reviewed and the champions would like to hear more when you have additional information to share. The follow-up team will be in contact early next week". Sadly I did not hear from the follow-up team. Our work has progressed since then and I am now attaching the paper describing our comparison of saliva and blood for detection of antibodies. Saliva is good because you can use it to detect both antigen (PCR) and antibodies. Importantly, we have developed dried blood spot for home testing and use in LMIC countries.

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Tom Jordan 6 months ago

Hi David,

Apologies for the lack of recent contact on this. We will revisit this and look over the paper you have attached. Our review group next convenes this Thursday and so I will make sure this gets considered.

Tom
Testing Methods team

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