| Autor: |
Berens, Shawn J., Brayton, Kelly A., McElwain, Terry F. |
| Zdroj: |
Infection and Immunity; December 2007, Vol. 75 Issue: 12 p5769-5776, 8p |
| Abstrakt: |
ABSTRACTAntigenic polymorphism is a defining characteristic of the Babesia bovisvariable merozoite surface antigen (VMSA) family. Sequence analysis strongly suggests that recombination between virulent strains contributes to VMSA diversity. While meiosis during the aneuploid stage of the parasite's life cycle in the tick vector Rhipicephalus(Boophilus) microplusis the most probable source of interstrain recombination, there is no definitive evidence that coinfection of the mammalian host or R. microplusticks with more than one virulent strain occurs. Using allele-specific real-time quantitative PCR, we tested the hypotheses that cattle could support coinfection of two antigenically variant virulent tick-transmissible strains of B. bovisand that R. microplusticks could acquire and transmit these two divergent strains. The results indicate that both calves and ticks can support virulent B. boviscoinfection through all phases of the hemoparasite's life cycle. Neither strain dominated in either the mammalian or invertebrate host, and larval tick progeny, which could be coinfected individually, were also able to transmit both strains, resulting in virulent babesiosis in recipients. While coinfection of the tick vector provides the context in which allelic antigenic diversity can be generated, recombination of VMSA genes could not be confirmed, suggesting that VMSA allelic changes are slow to accumulate. |
| Databáze: |
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