Humoral and Cell-Mediated Immune Response Validation in Calves after a Live Attenuated Vaccine of Babesia bigemina.

Umber Rauf,Asadullah Abid,Harish Menghwar,Aneela Zameer Durrani,Hamna Jamil,Haroon Akbar,Muhammad Imran Rashid,Muhammad Suleman

doi:10.3390/pathogens9110936

Umber Rauf, Asadullah Abid + Show 6 more

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https://doi.org/10.3390/pathogens9110936

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Abstract

The current vaccines to control bovine Babesia bigemina (B. bigemina) infection are not fully protective and vaccination failures incur heavy losses to the cattle industry around the world. Using modified micro-aerophilous stationary phase, we developed a culture-derived attenuated live vaccine against B. bigemina and tested a single subcutaneous inoculation of 2 × 108 infected erythrocytes in calves. The protection was measured after a lethal intravenous challenge with 5 × 108 virulent calf-derived B. bigemina. Our results demonstrated that a single shot of attenuated vaccine was capable of inducing robust humoral and cell-mediated immune responses in calves. We found a significant increase in the IgG antibody titers post-challenge and a strong proliferation of both CD4+ and CD8+ T cells contributing towards the protection. Our vaccine provided complete protection and parasitic clearance, which was followed for more than 100 days post-challenge. This immunity against babesiosis was directly linked to strong humoral responses; however, the parasitic clearance was attributed to significant T cells effector responses in vaccinated calves as compared to the infected control calves. We anticipate that these results will be helpful in the development of more efficient culture-derived vaccines against Babesia infections, thus reducing significant global economic losses to farmers and the cattle industry.

Highlights

Bovine babesiosis is an emerging disease that proves fatal and causes enormous economic loss worldwide in many ways—such as direct treatment cost, the indirect cost of low meatPathogens 2020, 9, 936; doi:10.3390/pathogens9110936 www.mdpi.com/journal/pathogensPathogens 2020, 9, 936 production and loss of milk production [1]
It is well documented that widely used chemotherapeutic compounds like diminazene aceturate and imidocarb dipropionate have an ample spectrum against this apicomplexan hemoprotozoan pathogen for bovine babesiosis [6,7]; but the repeated use of these drugs has led to the development of drug resistance in the tick-borne hemoprotozoan parasite [8,9], which has residual impact on milk and meat for a longer period, even after treatment [10]
The parasitemia levels observed in B. bigemina infected control calves in group C were at 3% ±0.5, whereas the parasitemia levels in vaccinated calves post-challenge were at 0.8% ±0.2

Summary

Introduction

Bovine babesiosis is an emerging disease that proves fatal and causes enormous economic loss worldwide in many ways—such as direct treatment cost, the indirect cost of low meatPathogens 2020, 9, 936; doi:10.3390/pathogens9110936 www.mdpi.com/journal/pathogensPathogens 2020, 9, 936 production and loss of milk production [1]. It is well documented that widely used chemotherapeutic compounds like diminazene aceturate and imidocarb dipropionate have an ample spectrum against this apicomplexan hemoprotozoan pathogen for bovine babesiosis [6,7]; but the repeated use of these drugs has led to the development of drug resistance in the tick-borne hemoprotozoan parasite [8,9], which has residual impact on milk and meat for a longer period, even after treatment [10]. The aforementioned drugs are banned or restricted by the Food and Drug Administration in many countries [11] This drug resistance development highlights the need for the exploration of new pharmaceutical agents with effective babesicidal activity and low toxicity in the host [12,13]

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