Immune Response Varied Among COVID-19 Patients: Study
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Antibody and immune responses to SARS-CoV-2, the virus that causes COVID-19, varied substantially among convalescing patients, a small study found.

The plasma of 41 patients in Australia recovering from COVID-19 showed antibodies, memory B cells, and circulating follicular helper T cells against the SARS-CoV-2 spike glycoprotein, but there was a range of certain B and T cell responses and frequency among individuals, reported researchers of the University of Melbourne in Australia writing in Nature Medicine.

Patients in the study were adults with mild to moderate COVID-19 infection, with serological assays performed about a month after positive PCR tests for SARS-CoV-2. Median age of patients was 59, and 24 were men.

Spike-specific antibodies, memory B cells, and circulating follicular helper T cells were present in all participants. Neutralizing antibody titers were generally "modest," which was "consistent with other reports in convalescent cohorts," authors indicated.

But when analyzing how neutralizing activity correlated with specific cells, the authors found two inverse relationships. First, neutralization activity positively correlated with spike and receptor-binding domain antibody titers, spike- and receptor-binding domain-specific B cell frequencies, and spike-specific circulating follicular helper T cells, but was inversely correlated with a particular type of spike-specific follicular helper T cell expressing certain chemokine receptors.

Similar to recent reports, spike protein-specific antibody and spike protein-specific circulating follicular helper T cells were associated with participants' reported severity of symptoms.

Since the goal of a vaccine is to elicit neutralizing antibodies targeting the spike protein of the virus, which would prevent it from binding to ACE2 in human cells, this could have implications for "spike-based vaccine prototypes," as it has been unclear how these models would work in humans, the authors added.

Source: https://www.nature.com/articles/s41591-020-0995-0
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