![]() Like other beta-coronaviruses (SARS-CoV-1 and Middle East respiratory syndrome-related coronavirus), SARS-CoV-2 employs an RNA-dependent RNA polymerase to replicate its genomic RNA and transcribe subgenomic RNAs ( 21– 24). SARS-CoV-2 is a positive-stranded RNA virus. ![]() Furthermore, no replication-competent virus was isolated or spread from these PCR-positive patients ( 1– 3, 5, 6, 12, 16), and the cause for the prolonged and recurrent production of viral RNA remains unknown. Although bona fide reinfection with SARS-CoV-2 after recovery has recently been reported ( 18), cohort-based studies with subjects held in strict quarantine after they recovered from COVID-19 suggested that at least some “re-positive” cases were not caused by reinfection ( 19, 20). Because we have detected only subgenomic sequences derived mainly from the 3′ end of the viral genome integrated into the DNA of the host cell, infectious virus cannot be produced from the integrated subgenomic SARS-CoV-2 sequences.Ĭontinuous or recurrent positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) PCR tests have been reported in samples taken from patients weeks or months after recovery from an initial infection ( 1– 17). The integration and transcription of viral sequences may thus contribute to the detection of viral RNA by PCR in patients after infection and clinical recovery. We also found, in some patient-derived tissues, evidence suggesting that a large fraction of the viral sequences is transcribed from integrated DNA copies of viral sequences, generating viral–host chimeric transcripts. We found target site duplications flanking the viral sequences and consensus LINE1 endonuclease recognition sequences at the integration sites, consistent with a LINE1 retrotransposon-mediated, target-primed reverse transcription and retroposition mechanism. In support of this hypothesis, we found that DNA copies of SARS-CoV-2 sequences can be integrated into the genome of infected human cells. We investigated the possibility that SARS-CoV-2 RNAs can be reverse-transcribed and integrated into the DNA of human cells in culture and that transcription of the integrated sequences might account for some of the positive PCR tests seen in patients. Learn about Batten disease research at Sanford Health here.Prolonged detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA and recurrence of PCR-positive tests have been widely reported in patients after recovery from COVID-19, but some of these patients do not appear to shed infectious virus. See the Medical Ethics lesson for more.Ĭlinical trials for several types of Batten disease are currently underway. It may be useful to spend some extra time discussing gene therapy as it can raise many ethical questions. There is no cure, but it can be treated.ĭiscuss the two options for treatments. Discuss the causes and symptoms of Batten disease. Show this video about the disease and gene therapy to learn more about the various types of Batten disease. The symptoms of the patient are consistent with Batten disease. Ask students to search and figure out which disease matches the clinical test results. Use the DNA Mutation worksheet to help students identify how different types of DNA mutations can affect the resulting proteins. It is a subunit of hemoglobin, which is responsible for carrying oxygen for red blood cells. Have them do a quick search to identify the function of this protein.Īnswer: The protein is beta-globin. Once they have their amino acid code, ask them to look in the protein box and identify which protein they have encoded. Next, ask students to use the codon box to translate mRNA into a polypeptide. Ask students to break the DNA into codons and then transcribe the DNA into mRNA. ![]() This can be used during the lesson or be assigned outside of class. Use the Transcription and Translation printable activity sheet to help students understand the basic process. This can be skipped if students already understand protein synthesis. Go through the following slides from the slideshow to discuss how DNA is transcribed into mRNA and then translated into protein. On the patient chart, ask students to record the results of different tests that were performed on the patient. ![]() The goal of this lesson is to help students identify the underlying cause of Blake’s condition. Next, show the video “ Finding a Diagnosis.”Īsk students to fill out the Mock Patient Chart with the symptoms they hear in the video. Begin with the From DNA to Protein slideshow. ![]()
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