Stability of HIV-1/2 antibodies in dried blood spots stored for up to 13 months under various environmental conditions in Brazil
Objectives: Dried blood spot (DBS) is an affordable and reliable method for the collection, transport and storage of samples for serologic and molecular assays. HIV antibody concentrations in DBS are stable for up to 6 weeks, however, it declines steadly thereafter. Our objective was to evaluate the stability of HIV antibodies in DBS stored for short and long periods under room temperature and controlled conditions.
Methods: Four sets of DBS cards originated from a panel (n=10) of HIV positive (n=5) and negative (n=5) specimens from reference whole blood–EDTA were transferred to filter paper (S&S 903) and dried. Cards were placed in zip-lock bags with desiccant and panels were stored in different environments: room temperature (RT), 4°C, -20°C or -70°C. DBS panels were screened at baseline, 6, 11, 17, 21, 42 and 53 weeks by Q-Preven HIV 1/2 (Q-preven, Brazil), a validated DBS assay. Humidity and temperature were recorded daily and optical density (OD) ratios were obtained.
Results: With storage under 4°C, -20°C and -70°C (humidity <50%) all HIV positive and negative samples remained concordant with stable OD ratios. One low-titer (1/5) HIV-positive at 4°C presented a 50% decrease in OD ratio over time, remaining positive. For RT, mean temperature was 22.2°C (range 27.2 - 12.1). Humidity remained >50% during most of the 53 weeks (mean 59.5%; range 72% - 45%). During the initial 6 weeks, all specimens maintained their serological status. Decrease of OD ratios was seen at 6 weeks with high-titer positives losing reactivity at 11 weeks. Negatives did not change status.
Conclusions: DBS can be stored effectively for 53 weeks (13.2 months) at 4°C, -20°C and -70°C and for 6 weeks at room temperature with humidity >50%, simulating field conditions. DBS use for the detection of HIV antibody is a convenient tool for HIV surveillance in remote areas of Brazil.
da Silva de Souza R.1, Borges L.G.1, do Amaral Inocêncio L.2, de Souza D.2, Motta L.1
Universidade de Caxias do Sul - Laboratório de Pesquisa em HIV/AIDS