12 May Hydrochloroquine not active in macaques and rapid tests CRISPR-Cas

Tue, 05/12/2020 - 17:53
  1. A very nice paper by the group of Roger Legrand in Paris, showing that hydroxychloroquine (HCQ) used at a similar concentration as in humans has no prophylactic or therapeutic effect on SARS-CoV-2 infection in cynomolgus macaques.  They also show that it is active in vitro on infection of Vero cells in the low µM range, but NOT in a human airway epithelium. The plasma concentration was below the IC50 value in Vero cells.


  1. Simplified and fast testing for SARS-CoV-2 based on CRISP-Cas (see 2 papers, editorial and review).  These platforms use the following simplifications:


  • Based on a swab or other sample RNA is extracted and reverse transcribed.
  • Primers for specific regions in E or N are applied.
  • No thermocycler (for PCR), but iso-thermal amplification strategies (just requiring a water bad), such as RPA (recombinase polymerase amplification) or LAMP (loop-mediated amplification) are used
  • The CRISPR Cas 12 or 13 is used to recognize a specific sequence by a specific guide RNA.  If this sequence is present, the Cas enzyme is activated and that will cleave a single stranded DNA reporter, which starts to fluoresce.
  • The detection is done either in a plate reader or a lateral flow devise  
  • The whole procedure is very rapid (40 minutes) and has a high specificity and sensitivity.

See figure 8 p. 12 (Esbin), Fig 1 p.5 (Curti) or  Fig 1 p.2 (Broughton).


Best wishes,