Covid, how infectious is a sick person? Italian technique measures it

How infectious is someone infected with Covid-19? An Italian technique allows to measure it and earns the pages of the magazine ‘Communications Biology’. The article is signed by a team of the Institute of Biomembranes, Bioenergetics and Molecular Biotechnologies of the National Research Council (Cnr-Ibiom) of Bari, of the University of Bari ‘Aldo Moro’, of the State University of Milan, of the Experimental Zooprophylactic Institute of Puglia and Basilicata and of the Covid Laboratory of the ‘Di Venere’ hospital in Bari, with the support of the genomics and bioinformatics platform made available by the Italian node of the Elixir European research infrastructure for life sciences. The authors analyzed 166 people affected by Covid with different degrees of viral load, developing “a methodology to determine the absolute number of viral Rna molecules contained in the molecular swabs used to identify the positivity to the virus”, explains a note. “Following the Sars-Cov-2 infection”, in fact, “the virus produces two types of Rna molecules: an Rna strand of about 30 thousand nucleotides, corresponding to the complete genome of the virus; a series of discontinuous Rna molecules , also called subgenomic transcripts, which code for the proteins necessary to assemble new virions and are necessary for the replication of the virus. These molecules therefore constitute an index of viral replication activity and, indirectly, of the degree of infectivity “of a positive at pandemic coronavirus. “The new methodology developed, based on the use of the ‘droplet digital Pcr’ (ddPcr) technique – specifies Graziano Pesole of the Cnr-Ibiom – allows to separately count the number of genomic and subgenomic RNA molecules”, while ” standard molecular tests currently used, based on the ‘real time PCR’, are not able to discriminate between the two types of viral RNA “, one of which is precisely indicative of the level of infectivity of an infected Covid. “Since the subgenomic molecules are markers of an ongoing infectious process, in which there is the proliferation of new viral particles”, according to the researchers “approaches based on this principle can be applied in the future to determine the degree of infectivity of a person. , even over time “. “The study – Pesole points out – showed that the percentage of subgenomic Rna is correlated to the viral load and is also similarly determinable by analysis by massive sequencing of the transcriptome”. “The results presented – he concludes – contribute to a better understanding of the dynamics of Sars-CoV-2 expression in different conditions, and to develop innovative diagnostic strategies to face the pandemic”.