Comparative Analysis of the Serological Reactivity of Individuals with Clinical History of Malaria using Two Different ELISA Tests.

Yorleydy Ruiz Moreno,Marcelo Sousa Silva,Fátima Nogueira,Silvia Tavares Donato

doi:10.3390/diagnostics9040168

Abstract

Early diagnosis of malaria reduces disease, prevents deaths, and contributes to decreased malaria transmission. The use of specific and sensitive antigens in the execution of serological diagnostics may have an impact on the transmission of the disease. However, many individuals cannot be easily diagnosed by serological tests due to low levels of antibodies in the serum. Using two different Enzyme-Linked Immunosorbent Assay (ELISA) tests (a commercial and an in-house ELISA), a total of 365 serum samples from individuals with a clinical history of malaria were analyzed. From the serum samples analyzed, 192 (53%) samples from the commercial ELISA and 219 (60%) samples from the in-house ELISA presented positive serological reactivity to malaria. The concordance of the samples tested (n = 365) between both ELISAs was of 67% (n = 242), and with the negative control was 100% (n = 17). We demonstrated that the in-house ELISA showed high antigenic reactivity to Plasmodium falciparum antigens when compared with the commercial ELISA. The degree of concordance of both ELISAs suggested the possibility of existence of other P. falciparum antigens present in the crude extract of P. falciparum that are important in the serological response during malaria infection.

Highlights

Diagnosis and treatment of human malaria reduces disease, prevents deaths, and contributes to reduced transmission [1]
The capacity of P. falciparum 3D7 crude extract to recognize antibodies anti-P. falciparum by an in-house Enzyme-Linked Immunosorbent Assay (ELISA) was compared with results obtained from a commercial ELISA, which incorporates recombinant antigens of P. vivax, P. falciparum, P. malariae, and P. ovalae
The degree of concordance of the two ELISAs, suggesting the possibility of other important antigens being involved in the serological response during human malaria, indicated that crude antigens were more reactive to ELISA than recombinant proteins

Summary

Introduction

Diagnosis and treatment of human malaria reduces disease, prevents deaths, and contributes to reduced transmission [1]. Detection of antibody response against malaria antigens is often done through Enzyme-Linked Immunosorbent Assay (ELISA) [2]; many of these diagnostic assays are designed with a single antigen or with recombinant antigens of different stages of the parasites (tissue infection or blood), where merozoite surface proteins can be detected, and have demonstrated good sensitivity and specificity [3]. Many individuals cannot be diagnosed due to the low levels of antibodies present in their blood In this context, the use of ELISA as a tool for laboratory diagnosis of malaria has some limitations, namely: (i) low antibody titres presented by individuals in the acute phase of infection; (ii) many Plasmodium sp. It should be considered that single responses of antibodies against antigens might be inadequate to for use as biomarkers and indicators of malaria transmission intensity [6]

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Discussion

Conclusion