Improved heat shock method for extracting total RNA from nasopharyngeal swab samples even with low viral load

Diagn Microbiol Infect Dis. 2024 May;109(1):116210. doi: 10.1016/j.diagmicrobio.2024.116210. Epub 2024 Feb 10.

Abstract

This study aimed to improve the heat shock method as a cost-effective and time-efficient for total RNA extraction. We compared the effectiveness of two total RNA extraction methods by using Real-Time PCR for nasopharynx swabs. Include: I; use of a commercial total RNA extraction kit as a standard. II; utilized a modified heat shock method (MHS). Time, centrifuge speed and duration, proteinase K, and RNA carrier were optimized. The optimized parameters included treating the sample with 5 μg/μL at 56°C for 5 minutes, heating at 95°C for 5 minutes followed by thermal shock in ice for 3 minutes, adding 4 μg/μL RNA carrier at room temperature for 3 minutes, and centrifuging at 7000 rpm for 10 minutes. This optimization demonstrated a sensitivity and specificity of 100% (CI: 95%) even in samples with low viral load. Our in-house method presents a rapid, and cost-effective alternative for total RNA extraction.

Keywords: Extraction kit; Heat shock; SARS-COV-2; Total RNA.

MeSH terms

  • COVID-19 Testing / methods
  • COVID-19*
  • Clinical Laboratory Techniques / methods
  • Heat-Shock Response
  • Humans
  • Nasopharynx
  • RNA, Viral / analysis
  • RNA, Viral / genetics
  • SARS-CoV-2 / genetics
  • Sensitivity and Specificity
  • Specimen Handling / methods
  • Viral Load

Substances

  • RNA, Viral