Please cite this article in press as: Bilhassi, T.B., et al., Quantitative study of Babesia bovis infection in beef cattle from São Paulo state, Brazil. Ticks Tick-borne Dis. (2014), http://dx.doi.org/10.1016/j.ttbdis.2013.11.002 ARTICLE IN PRESS G Model TTBDIS-275; No. of Pages 5 Ticks and Tick-borne Diseases xxx (2014) xxx–xxx Contents lists available at ScienceDirect Ticks and Tick-borne Diseases j ourna l h o me page: w ww.elsevier.com/locate/ttbdis Original article Quantitative study of Babesia bovis infection in beef cattle from São Paulo state, Brazil Talita B. Bilhassi a , Henrique N. Oliveira a,∗ , Adriana M.G. Ibelli b , Rodrigo Giglioti a , Luciana C.A. Regitano c , Teresa C.G. Oliveira-Sequeira d , Flávia A. Bressani c , Wilson Malagó Jr. c , Flávio D. Resende e , Márcia C.S. Oliveira c a Universidade Estadual Júlio de Mesquita Filho, Jaboticabal, SP, Brazil b Embrapa Suínos e Aves, Concórdia, SC, Brazil c Embrapa Pecuária Sudeste, São Carlos, SP, Brazil d Universidade Estadual Júlio de Mesquita Filho, Botucatu, SP, Brazil e APTA/Pólo Regional Alta Mogiana, Colina, SP, Brazil a r t i c l e i n f o Article history: Received 7 March 2013 Received in revised form 25 October 2013 Accepted 4 November 2013 Available online xxx Keywords: Babesiosis Beef cattle qPCR B. bovis a b s t r a c t The qPCR technique with SYBR Green was used to estimate the prevalence and level of Babesia bovis infec- tion in beef cattle raised in areas endemic for babesiosis in Brazil, where the animals were continuously exposed to ticks (Rhipicephalus microplus). This is the first report in which qPCR was used to quantify and compare B. bovis DNA in blood of different cattle breeds. Blood samples were collected from 150 animals (75 cows and 75 calves) of the Angus and Nelore breeds and the first generation of an Angus and Nelore cross (AxN). Blood samples from the jugular vein were used for DNA extraction and determina- tion of packed cell volume (PCV), while samples from peripheral veins were used for microscopic parasite detection. Although no piroplasms of B. bovis were found in blood smears, DNA amplification using qPCR revealed that all of the 150 animals, except two calves and one cow, were positive. The number of copies of B. bovis DNA was higher (p < 0.05) in the Angus than in the Nelore and AxN animals, for both calves and cows, but no significant difference was found between the Nelore and AxN groups. These results suggest that a heterotic effect was present, since the results from the crossbred animals significantly deviated from the mean of the two parental groups, while closely approaching that of the Nelore group. In the Nelore and AxN groups, calves showed higher infection levels than cows (p < 0.05), while for the Angus group the difference was found to be non-significant. Within each animal age group, the breed groups with higher infection levels were those with lower PCV values. However, within each breed group, no significant correlations were found between the number of DNA copies and PCV according to animal age. The qPCR method applied here allowed the observation that although there are no differences in the prevalence of infection among breed groups, Nelore and AxN cattle are able to maintain infection by B. bovis at lower levels than the Angus cattle. © 2014 Elsevier GmbH. All rights reserved. Introduction Bovine babesiosis is a tick-borne disease (TBD) caused by sev- eral species of intraerythrocytic protozoa of the genus Babesia. These infections reduce the productivity of cattle herds and cause substantial economic losses, particularly in developing countries (Nari, 1995). In Brazil, bovine babesiosis is caused by Babesia bovis ∗ Corresponding author at: Via de Acesso Prof. Paulo Donato Castellane s/n, 14884- 900 Jaboticabal, SP, Brazil. Tel.: +55 16 3209 2678; fax: +55 16 32092679. E-mail addresses: oliveira.hn@gmail.com, holiveira@fcav.unesp.br (H.N. Oliveira). and Babesia bigemina, which are exclusively transmitted by Rhipi- cephalus microplus. Babesia bovis is the most pathogenic species, and animals that survive primary infection develop strong immu- nity. In B. bovis infections, excessive production of cytokines and other substances in relation to the immune response (Bock et al., 2004; Chauvin et al., 2009) contributes toward disease progression, including damage to the central nervous system (Al-Khedery and Allred, 2006). Regarding host resistance, it has been well established that breeds vary in their resistance to ticks, and although there is less information available on genetic resistance to babesiosis, variation among cattle breeds has been reported (Bock et al., 1997, 1999; Aguirre et al., 1990). Bos taurus indicus breeds are more resistant http://dx.doi.org/10.1016/j.ttbdis.2013.11.002 1877-959X/© 2014 Elsevier GmbH. All rights reserved.