Sialylation Shifts in Visceral Leishmaniasis: Altered Sialidases and Sialyltransferases Expression in Spleen and Liver Tissues of <i>Leishmania donovani</i> Infected <scp>BALB</scp> /c Mice

Sias on host cell influence host-pathogen interactions. Pathogens often manipulate sialylation machinery by downregulating sialidases or upregulating sialyltransferases to suppress immune response. However, the sialylation dynamics in visceral leishmaniasis (VL) caused by Leishmania donovani (L.d) remain unexplored. Accordingly, we investigated the expression changes of sialidases (Neu1, Neu2, and Neu3) and sialyltransferases (ST3Gal1, ST3Gal5, and ST6Gal1) in the spleen and liver of L.d- infected BALB/c mice using droplet digital polymerase chain reaction. Parasite load quantification and monitoring amastigote-specific A2 gene confirmed infection. We observed downregulation of all sialidases (Neu1, Neu2, and Neu3) in contrast to an upregulation of sialyltransferases-ST3Gal1 and ST3Gal5. Notably, splenic sialidases exhibited a strong negative correlation with A2 (Neu1: r = -0.81, Neu2: r = -0.78), suggestive of reduced desialylation. Conversely, both the sialyltransferases ST3Gal1 and ST3Gal5 strongly positively correlated with A2 (r = 0.81, r = 0.89 respectively). These suggest an active modulation of host sialylation during infection that can be explored for therapeutic interventions against VL.