A study published in Nature looks at the evolution of SARS-CoV-2 during treatment of chronic infection.
Prof Jonathan Ball, Professor of Molecular Virology, University of Nottingham, said:
“This is an interesting study that shows how quickly coronavirus variants can emerge in response to antibody pressure. However, when serum antibody treatment faded over time, the variant decreased in frequency, suggesting that the variant was less fit than the original infecting wild type virus. This is important and highlights that the virus will be experiencing lots of different, often opposing, selective pressures, and we need to remember that whenever we consider the potential impact and spread of new variants.”
Prof Lawrence Young, Virologist and Professor of Molecular Oncology, University of Warwick, said:
“Confirmation that an inadequate immune response drives development of virus variants. This study provides a detailed examination of the emergence of SARS-CoV-2 variants in a single immunosuppressed individual treated with convalescent plasma. It clearly shows the dynamic nature of variations in the virus population within a single individual and how the virus adapts in response to passive antibodies in a host with a weakened immune response. It shows that one of the changes observed in the UK variant (69-70del) was generated in this individual and accounts for the increased infectiousness of this variant. Another mutation that emerged along with 69-70del, D796H, reduced sensitivity to neutralisation by convalescent plasma. The study highlights the need for careful monitoring of immune compromised patients treated with convalescent plasma and assumes that it is the lack of a more sustained immune response including cytotoxic T cells that favours the emergence of virus escape mutations. It is difficult to extrapolate from a single case report but the data is consistent with our growing understanding of the mutations present in SARS-CoV-2 variants and how these are emerging as the virus adapts to us in terms of transmissibility and immune evasions. It reinforces concerns that weakened immune responses in either immunocompromised individuals or those with a partial immune response to the virus (e.g. by waning immunity post-infection or inadequate response to vaccination) could be the source of further variations in the virus.”
‘SARS-CoV-2 evolution during treatment of chronic infection’ by Steven Kemp et al was published in Nature at 16:00 UK time on Friday 5 February.
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