Examination of antisense RNA and oligodeoxynucleotides as potential inhibitors of avian leukosis virus replication in RP30 cells

Antisense oligonucleotides targeting ORF1b block replication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)

The ongoing COVID-19 pandemic continues to pose a need for new and efficient therapeutic strategies. We explored antisense therapy using oligonucleotides targeting the severe acute respiratory syndrome coronavirus (SARS-CoV-2) genome. We predicted in silico four antisense oligonucleotides (ASO gapmers with 100% PTO linkages and LNA modifications at their 5' and 3'ends) targeting viral regions ORF1a, ORF1b, N and the 5'UTR of the SARS-CoV-2 genome. Efficiency of ASOs was tested by transfection in human ACE2-expressing HEK-293T cells and monkey VeroE6/TMPRSS2 cells infected with SARS-CoV-2. The ORF1b-targeting ASO was the most efficient, with a 71% reduction in the number of viral genome copies. N- and 5'UTR-targeting ASOs also significantly reduced viral replication by 55 and 63%, respectively, compared to non-related control ASO (ASO-C). Viral titration revealed a significant decrease in SARS-CoV-2 multiplication both in culture media and in cells. These results show that anti-ORF1b ASO can specifically reduce SARS-CoV-2 genome replication in vitro in two different cell infection models. The present study presents proof-of concept of antisense oligonucleotide technology as a promising therapeutic strategy for COVID-19.

A selection strategy in plant transformation based on antisense oligodeoxynucleotide inhibition

Antisense oligodeoxynucleotide (asODN) inhibition was developed in the 1970s, and since then has been widely used in animal research. However, in plant biology, the method has had limited application because plant cell walls significantly block efficient uptake of asODN to plant cells. Recently, we have found that asODN uptake is enhanced in a sugar solution. The method has promise for many applications, such as a rapid alternative to time-consuming transgenic studies, and high potential for studying gene functionality in intact plants and multiple plant species, with particular advantages in evaluating the roles of multiple gene family members. Generation of transgenic plants relies on the ability to select transformed cells. This screening process is based on co-introduction of marker genes into the plant cell together with a gene of interest. Currently, the most common marker genes are those that confer antibiotic or herbicide resistance. The possibility that traits introduced by selectable marker genes in transgenic field crops may be transferred horizontally is of major public concern. Marker genes that increase use of antibiotics and herbicides may increase development of antibiotic-resistant bacterial strains or contribute to weed resistance. Here, we describe a method for selection of transformed plant cells based on asODN inhibition. The method enables selective and high-throughput screening for transformed cells without conferring new traits or functions to the transgenic plants. Due to their high binding specificity, asODNs may also find applications as plant-specific DNA herbicides.