![transcribe dna transcribe dna](https://i.ytimg.com/vi/NQT0avhrRlw/hqdefault.jpg)
![transcribe dna transcribe dna](https://3.bp.blogspot.com/_lk6MuzljD_Y/TT2oFB54nlI/AAAAAAAAAA0/reRf83iIGAs/s1600/dna-transcription.jpg)
For example, the fact that influenza is an RNA virus is one reason a new flu vaccine is needed every year. This leads to more rapid evolution and variants in RNA viruses. For this reason, mutations (changes in the nucleotide sequence) occur more frequently in RNA viruses than in DNA viruses. Because of the error rate of the enzymes involved in RNA replication, these viruses show a much higher mutation rate than DNA viruses. To replicate their genomes in the host cell, the genomes of RNA viruses encode enzymes not found in host cells. RNA viruses, comprising 70% of all viruses, contain only RNA in their core. DNA viruses cause human diseases such as chickenpox, Hepatitis B, and some venereal diseases like herpes and genital warts. The viral DNA directs the host cell’s replication proteins to synthesize new copies of the viral genome, and to transcribe and translate that genome into viral proteins. Attachment is a requirement for viruses to later penetrate the cell membrane, inject the viral genome, and complete their replication inside the cell.ĭNA viruses have a DNA core. The virus exploits these cell-surface molecules as a way to recognize and infect specific cell types. All viruses use some sort of glycoprotein to attach to their host cells via molecules on the host cell called viral receptors. This is a lipid bilayer derived from the modified host cell membrane and studded with an outer layer of virus envelope glycoproteins. Some virus families have an additional outer covering surrounding the nucleocapsid, called an envelope. Unlike all living organisms that use DNA as their genetic material, viruses may use either DNA or RNA, which may be single stranded (ss) or double stranded (ds), linear or circular. The simplest virions contain two basic components: a nucleic acid core (genetic material) and a capsid (an outer protective protein coat), jointly referred to as the nucleocapsid. This novel feature of SARS-CoV-2 infection may explain why patients can continue to produce viral RNA after recovery and suggests a new aspect of RNA virus replication.Viruses are diverse and varied in their complexity. Human endogenous LINE-1 expression was induced upon SARS-CoV-2 infection or by cytokine exposure in cultured cells, suggesting a molecular mechanism for SARS-CoV-2 retro-integration in patients. To experimentally corroborate the possibility of viral retro-integration, we describe evidence that SARS-CoV-2 RNAs can be reverse transcribed in human cells by reverse transcriptase (RT) from LINE-1 elements or by HIV-1 RT, and that these DNA sequences can be integrated into the cell genome and subsequently be transcribed. In support of this hypothesis, we found chimeric transcripts consisting of viral fused to cellular sequences in published data sets of SARS-CoV-2 infected cultured cells and primary cells of patients, consistent with the transcription of viral sequences integrated into the genome. Here we investigated the possibility that SARS-CoV-2 RNAs can be reverse-transcribed and integrated into the human genome and that transcription of the integrated sequences might account for PCR-positive tests. Prolonged SARS-CoV-2 RNA shedding and recurrence of PCR-positive tests have been widely reported in patients after recovery, yet these patients most commonly are non-infectious.