title: Sensitivity of a rapid point of care assay for early HIV antibody detection is enhanced by its ability to detect HIV gp41 IgM antibodies.
abstract: BACKGROUND
  Anti-HIV-1 IgM antibody is an important immunoassay target for early HIV antibody detection.
  
  
  OBJECTIVE
  The objective of this study is to determine if the early HIV antibody sensitivity of the 60s INSTI test is due to detection of anti-HIV-1 IgM in addition to IgG.
  
  
  METHODS
  To demonstrate HIV gp41 IgM antibody capture by the INSTI HIV-1 gp41 recombinant antigen, an HIV-IgM ELISA was conducted with commercial HIV-1 seroconversion samples. To demonstrate that the INSTI dye-labelled Protein A-based colour developer (CD) has affinity to human IgM, commercial preparations of purified human immunoglobulins (IgM, IgD, IgA, IgE, and IgG) were blotted onto nitrocellulose (NC) and probed with the CD to observe spot development. To determine that INSTI is able to detect anti-HIV-1 IgM antibody, early seroconversion samples, were tested for reduced INSTI test spot intensity following IgM removal.
  
  
  RESULTS
  The gp41-based HIV-IgM ELISA results for 6 early seroconversion samples that were INSTI positive determined that the assay signal was due to anti-HIV-1 IgM antibody capture by the immobilised gp41 antigen. The dye-labelled Protein-A used in the INSTI CD produced distinct spots for purified IgM, IgA, and IgG blotted on the NC membrane. Following IgM removal from 21HIV-1 positive seroconversion samples with known or undetermined anti-HIV-1 IgM levels that were western blot negative or indeterminate, all samples had significantly reduced INSTI test spot intensity.
  
  
  CONCLUSIONS
  The INSTI HIV-1/HIV-2 Antibody Test is shown to detect anti-HIV-1 IgM antibodies in early HIV infection which enhances its utility in early HIV diagnosis.
authors: bioLytical Laboratories Inc., 1108-13351 Commerce Parkway, Richmond, BC V6V 2X7, Canada. Electronic address: nmoshgabadi@biolytical.com.
authors: Noushin
authors: N
authors: Moshgabadi
authors: bioLytical Laboratories Inc., 1108-13351 Commerce Parkway, Richmond, BC V6V 2X7, Canada.
authors: Rick A
authors: RA
authors: Galli
authors: bioLytical Laboratories Inc., 1108-13351 Commerce Parkway, Richmond, BC V6V 2X7, Canada.
authors: Amelia C
authors: AC
authors: Daly
authors: bioLytical Laboratories Inc., 1108-13351 Commerce Parkway, Richmond, BC V6V 2X7, Canada.
authors: Sze Mun Shirley
authors: SM
authors: Ko
authors: bioLytical Laboratories Inc., 1108-13351 Commerce Parkway, Richmond, BC V6V 2X7, Canada.
authors: Tayla E
authors: TE
authors: Westgard
authors: bioLytical Laboratories Inc., 1108-13351 Commerce Parkway, Richmond, BC V6V 2X7, Canada.
authors: Ashley F
authors: AF
authors: Bulpitt
authors: bioLytical Laboratories Inc., 1108-13351 Commerce Parkway, Richmond, BC V6V 2X7, Canada.
authors: Christopher R
authors: CR
authors: Shackleton
mesh_terms: D042241:Early Diagnosis; D015483:HIV Antibodies / Q000097:blood*; D015700:HIV Envelope Protein gp41 / Q000276:immunology*; D015658:HIV Infections / Q000175:diagnosis*; D006801:Humans; D007075:Immunoglobulin M / Q000097:blood*; D019095:Point-of-Care Systems; D012680:Sensitivity and Specificity; D012698:Serologic Tests / Q000379:methods*
chemical_list: D015483:HIV Antibodies; D015700:HIV Envelope Protein gp41; D007075:Immunoglobulin M
keywords: Anti-HIV-1 IgM antibody; Early detection; HIV gp41 antigen; INSTI; IgM removal; Protein A