Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 14 2 2019 06 19 310 317 EN Shamsi NOORPISHEH GHADIMI Department of Parasitology and Mycology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran Leila HOMAYOON Department of Parasitology and Mycology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran Reza SHAHRIARIRAD Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran Shakila FATEHPOUR Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran Mohammad RASTEGARIAN Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran Bahador SARKARI Department of Parasitology and Mycology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran AND Basic Sciences in Infectious Diseases Research Center, Shiraz University of Medical Sciences, Shiraz, Iran 2018 01 25 2019 06 19 Background: The current study aimed to investigate the possible cross-protective effects of attenuated L. major against L. infantum in BALB/c mice. Methods: This experimental study was performed in 2017 in Shiraz University of Medical Sciences, Shiraz, Iran. The attenuated strain of L. major was prepared by continuous weekly subculturing of the parasite. Forty-eight female BALB/c mice were divided into eight groups. Group 1 injected (ID) with wild type of L. major; group 2 injected (IV) with L. infantum; group 3 injected (ID) with attenuated L. major; group 4 injected (ID) with attenuated L. major, and after three weeks challenged (IV) with L. infantum; group 5 injected (IP) with attenuated L. major; group 6 injected (IP) with attenuated L. major, and challenged (IV) with L. infantum (IV); group 7 injected (IV) with attenuated L. major; and finally group 8 injected (IV) with attenuated L. major and after three weeks challenged (IV) with L. infantum. Forty-five days post-infection, the parasite load in the spleen and liver of the mice was determined as Leishman-Donovan units (LDU). Results: The differences in mean of LDU of spleen between different groups were statistically significant (P<0.048). In addition, the differences in percent of infection in liver between pairwise comparisons of groups were statistically significant (P<0.05). The highest intensity of infection was observed in group 2 while low intensity of infection was seen in groups 3, 4 and 5. Conclusion: Live attenuated L. major can induce substantial protection against L. infantum, particularly when the parasites were injected intravenously. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/1971 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/1971/948