Thermal stability of diagnostic targets plasmodium falciparum histidine rich protein Ⅱ and plasmodium lactate dehydrogenase in rapid detection

ABSTRACT

During the COVID-19 epidemic, blood samples are usually processed at 56 ℃ to attenuate the virus before pathogen detection. 71 blood samples of malaria patients reported by Shanghai Center for Disease Control and Prevention in 2017-2019 were collected, including 38 with Plasmodium falciparum infection, 8 P. malariae, 11 P. ovale and 14 P. vivax. The effect of inactivation on the thermal stability of P. falciparum histidine rich protein Ⅱ (PfHRPⅡ) and Plasmodium lactate dehydrogenase (pLDH) in blood samples was assessed before and after incubation at 56 ℃ for 30 min using the rapid diagnostic test (RDT) kit. The results showed that among the 38 P. falciparum T1-positive (PfHRPⅡ) blood samples before heat treatment, 35 samples remained to be T1-positive (92.11%, 35/38, χ2=3.123, P>0.05) after heat treatment;while 54 blood samples (26 P. falciparum, 6 P. vivax, 10 P. ovale and 12 P. vivax) that were T2-positive (pLDH) before heat treatment turned to be T2-negative (positive rate 0, 0/54, χ2=87.755, P<0.01) after heat treatment. It was demonstrated that PfHRPⅡ is stable during incubation at 56 ℃ for 30 min, while pLDH is unstable and degraded or inactivated during the heating. Therefore, the detection results of P. falciparum will not be affected by RDT, but diagnosis of the parasites other than P. falciparum in blood samples may be missed. © 2021, National Institute of Parasitic Diseases. All rights reserved.