Longitudinal evaluation of humoral immune response and merozoite surface antigen diversity in calves naturally infected with Babesia bovis, in São Paulo, Brazil

Abstract

Babesiosis is an economically important infectious disease affecting cattle worldwide. In order to longitudinally evaluate the humoral immune response against Babesia bovis and the merozoite surface antigen diversity of B. bovis among naturally infected calves in Taiaçu, Brazil, serum and DNA samples from 15 calves were obtained quarterly, from their birth to 12 months of age. Anti-B. bovis IgG antibodies were detected by means of the indirect fluorescent antibody test (IFAT) and enzyme-linked immunosorbent assay (ELISA). The polymerase chain reaction (PCR) was used to investigate the genetic diversity of B. bovis, based on the genes that encode merozoite surface antigens (MSA-1, MSA-2b and MSA-2c). The serological results demonstrated that up to six months of age, all the calves developed active immunity against B. bovis. Among the 75 DNA samples evaluated, 2, 4 and 5 sequences of the genes msa-1, msa-2b and msa-2c were obtained. The present study demonstrated that the msa-1 and msa-2b genes sequences amplified from blood DNA of calves positive to B. bovis from Taiaçu were genetically distinct, and that msa-2c was conserved. All animals were serologically positive to ELISA and IFAT, which used full repertoire of parasite antigens in despite of the genetic diversity of MSAs.

Genetic Diversity of Babesia bovis MSA-1, MSA-2b and MSA-2c in China

“…Antigenic polymorphism has been applied as a strategy by most protozoan parasites to escape the immune response of mammalian hosts, and it is a major obstacle preventing the development of effective vaccines against these parasites [7]. In our present study, analysis of the genetic relationships of B. bovis MSA-1, MSA-2b and MSA-2c of Chinese isolates, with respect to almost all available related sequences deposited in the GenBank database (including Mongolia, Vietnam, Philippines, Thailand, Israel, Vietnam, Sri Lanka, Mexico, Argentina, Brazil, Japan and USA) was conducted [7,12,[18][19][20][21][22][23][24]26,30,31]. Phylogenetic analysis showed that the MSA-1 amino acid sequences had a wide distribution in four clades.…”

“…Phylogenetic analyses of B. bovis MSAs have been performed in several countries, including Mongolia, Vietnam, the Philippines, Thailand, Israel, Vietnam, Sri Lanka, Mexico, Argentina and Brazil [7,12,[18][19][20][21][22][23][24][25][26]. In China, molecular epidemiological investigations of B. bovis infection have been performed in several provinces [4,5].…”

Genetic diversity of Babesia bovis studied longitudinally under natural transmission conditions in calves in the state of Rio de Janeiro, Brazil

“…The genetic diversity of msa (msa-1, msa-2b, and msa-2c) has been analyzed in several B. bovis-endemic countries in the recent past (Genis et al, 2009;Altangerel et al, 2012;Sivakumar et al, 2013). Studies conducted in Australia (Berens et al, 2005;LeRoith et al, 2005), Sri Lanka (Sivakumar et al, 2013), the Philippines (Tattiyapong et al, 2014), Thailand (Simking et al, 2013), Israel (Molad et al, 2014), Mexico (Borgonio et al, 2008;Genis et al, 2009) and Brazil (Nagano et al, 2013;Matos et al, 2017;Mendes et al, 2019) have found that B. bovis isolates in these countries are genetically diverse, according to their msa gene sequences.…”

“…This finding highlights the importance of conducting extensive studies on this subject before designing immune control strategies in this country (Nagano et al, 2013). Recently, Matos et al (2017) reported that while the B. bovis msa-1 and msa-2b gene sequences amplified from calves' blood samples from Taiaçu, São Paulo, southeastern Brazil, were genetically distinct, msa-2c sequences were conserved. Moreover, Mendes et al (2019) targeted the msa-2b and msa-2c genes and reported high genetic diversity of B. bovis in beef cattle sampled in the Pantanal biome, Mato Grosso do Sul, central-western Brazil.…”

“…The genetic diversity of B. bovis was previously shown based on MSA genes among cattle sampled in Australia (Berens et al, 2005;LeRoith et al, 2005), Brazil (Nagano et al, 2013;Matos et al, 2017;Simking et al, 2013;Mendes et al, 2019), Sri Lanka (Sivakumar et al, 2013), Philippines (Tattiyapong et al, 2014) and Israel (Molad et al, 2014). Antigenic variations arising from this genetic diversity result in different immune profiles in their hosts.…”