Varianti Lambda: Rezistent ndaj vaksinave dhe më ngjitës?

DISKUTIMI

High SARS-CoV-2 transmission is occurring in Chile despite an intensive vaccination campaign, which mostly relies on the inactivated virus vaccine from Sinovac Biotech and to a lesser extent in the mRNA vaccine from Pfizer/BioNTech and the non-replicative viral vector vaccines from Oxford/AstraZeneca and Cansino Biologicals.

The last surge reported in the country has been dominated by the SARS-CoV-2 variants Gamma and Lambda, the former classified as a variant of concern several months ago and the latter being recently recognized as a variant of interest by the WHO. While the Gamma variant possesses 11 mutations in the spike protein including those in the receptor-binding domain (RBD) associated with increased ACE2 binding and infectivity (N501Y) or immune escape (K417T and E484K) the spike protein of the Lambda variant has a unique pattern of 7 mutations (Δ246-252, G75V, T76I, L452Q, F490S, D614G, T859N) from which L452Q is similar to the L452R mutation reported in the Delta and Epsilon variants.

The L452R mutation has been shown to confer immune escape to monoclonal antibodies (mAbs) as well as convalescent plasma.

Moreover, the L452R mutation has also been shown to increase viral infectivity and our data suggest that the L452Q mutation present in the Lambda variant might confer similar properties to those described for L452R. Interestingly, the 246-252 deletion in the N-terminal domain (NTD) of the Lambda Spike is located in an antigenic supersite and therefore, this deletion might also contribute to immune escape. Moreover, the F490S mutation has also been associated with an escape to convalescent sera.

Consistent with these antecedents, our results indicate that the spike protein of the Lambda variant confers immune escape to neutralizing antibodies elicited by the CoronaVac vaccine. Whether the Lambda variant also escapes to the cellular response shown to be elicited by CoronaVac is still unknown.

We also observed that the spike protein of the Lambda variant presented increased infectivity when compared with the spike protein of the Alpha and Gamma variants, both of them with reported increased infectivity and transmissibility.

Together, our data show for the first time that mutations present in the spike protein of the Lambda variant confer escape to neutralizing antibodies and increased infectivity. The evidence presented here reinforces the idea that massive vaccination campaigns in countries with high SARS-CoV-2 circulation rates must be accompanied by strict genomic surveillance aimed to rapidly identify new viral isolates carrying spike mutations as well as studies aimed to analyze the impact of these mutations in immune escape and vaccines breakthrough.

COVID-19 is fast progressing. This can be seen in Hawaii where numbers were low and jumped to record high with tourism booming.