Unraveling the immune regulatory mechanisms imposed by Anaplasma

Anaplasmosis in the Amazon: diagnostic challenges, persistence, and control of Anaplasma marginale and Anaplasma phagocytophilum

Anaplasmosis remains a significant threat to livestock production in tropical regions, particularly in the Amazon basin, where ecological complexity and limited veterinary infrastructure challenge effective disease management. This review focuses on Anaplasma marginale and Anaplasma phagocytophilum, the primary species associated with bovine and granulocytic anaplasmosis, respectively. We examine the current state of diagnostic tools, highlighting the limited accessibility of molecular techniques in rural settings and the emerging but underutilized potential of technologies. Persistent infection and antigenic variation are explored as major obstacles for disease eradication and vaccine development. Although live attenuated and inactivated vaccines are in use for A. marginale, none provide sterilizing immunity, and no commercial vaccines exist for A. phagocytophilum. The review evaluates recent advances in recombinant antigens, chimeric constructs, and genetically attenuated strains, as well as future directions involving multiepitope design, novel adjuvants, and next-generation vaccine platforms. Additionally, we assess the role of tick control in disease prevention and emphasize the importance of integrated strategies in regions like the Amazon. Together, these findings underscore the need for context-specific solutions that address the ecological and epidemiological complexity of anaplasmosis in the Amazon basin.

Persistent Infections and Immunity in Ruminants to Arthropod-Borne Bacteria in the Family Anaplasmataceae

Tick-transmitted gram-negative bacteria in the family Anaplasmataceae in the order Rickettsiales cause persistent infection and morbidity and mortality in ruminants. Whereas Anaplasma marginale infection is restricted to ruminants, Anaplasma phagocytophilum is promiscuous and, in addition to causing disease in sheep and cattle, notably causes disease in humans, horses, and dogs. Although the two pathogens invade and replicate in distinct blood cells (erythrocytes and neutrophils, respectively), they have evolved similar mechanisms of antigenic variation in immunodominant major surface protein 2 (MSP2) and MSP2(P44) that result in immune evasion and persistent infection. Furthermore, these bacteria have evolved distinct strategies to cause immune dysfunction, characterized as an antigen-specific CD4 T-cell exhaustion for A. marginale and a generalized immune suppression for A. phagocytophilum, that also facilitate persistence. This indicates highly adapted strategies of Anaplasma spp. to both suppress protective immune responses and evade those that do develop. However, conserved subdominant antigens are potential targets for immunization.