Reverse transcriptase (RT) component of antiviral defense system retron Ec78, composed of a non-coding RNA (ncRNA), this reverse transcriptase (RT), a probable ATPase and a putative HNH endonuclease. Expression of retron Ec78 confers protection against bacteriophage T5. At multiplicity of infection (MOI) of 0.02 cultures slow growth when infected with T5 but do not collapse, at MOI 2 cultures enter growth stasis (PubMed:33157039). Responsible for synthesis of msDNA-Ec78 (a linear ssDNA with a 5'-terminal phosphate residue). Unlike most known msDNAs the mature product does not have an RNA component. The retron transcript serves as primer and template for the reaction, and codes for the RT. Not mutagenic when cloned in E.coli (PubMed:9281493). It is thought to be synthesized as a branched RNA with a 2',5'-phosphodiester linkage to ssDNA; the linkage is cleaved endonucleolytically by ExoVII (xseA-xseB) leaving the observed mature 5'-ssDNA terminus (Probable) (PubMed:26626352). Overexpression of the ncRNA and RT, which leads to increased levels of msDNA, is not mutagenic in vivo. As the stem in the msDNA does not have a mismatch it probably does not bind or sequester MutS and/or MutL (PubMed:7885227). a 2'-deoxyribonucleoside 5'-triphosphate + DNA(n) = diphosphate + DNA(n+1) Belongs to the bacterial reverse transcriptase family.