Could Raman spectroscopy distinguish between P. falciparum and P. vivax Infection?

Abstract

The erythrocytes obtained from patients diagnosed with Plasmodium falciparum or Plasmodium vivax infection (two groups of five patients each) and treated in the Department of Infectious Diseases, University Hospital in Kraków, were measured using the Raman spectroscopy method (1–2 cells of each patient) and then compared with the results from these patients during their convalescence. Principal Component Analysis (PCA) was used to determine the variance between the Raman spectra. Changes in the heme structure were observed by the v₄ oxidation state marker and by other heme and hemozoin marker bands, as well as protein side chains marker bands. The recognized Raman bands allow to differentiate changes taking place in the red blood cells during the development of Plasmodium falciparum from Plasmodium vivax. The 1385 cm⁻¹ Asp band along with the 1587 cm⁻¹ Gln vibrations at the beginning of hospitalization specify the invasion of P. falciparum that occurs with the basigin receptor which requires respective protein glycosylation. The 1361 cm⁻¹ and 1544 cm⁻¹ Trp bands indicate the invasion stage of the P. vivax parasite, and the formation of the ligand-receptor complex. To our knowledge, this is the first Raman spectroscopic observation that we can distinguish Plasmodium species.