Immune system variation in Nilgai antelope

Authors: SLIWA, KATHRYN - Texas A&M University; NAVARRO, DAVID - Texas A&M University; OHNISHI, MASAHIRO - Texas A&M University; BAUMGARDT, JEREMY - Texas A&M University; DEYOUNG, RANDY - Texas A&M University; ORTEGA, ALFONSO - Texas A&M University; HEWITT, DAVID - Texas A&M University; Goolsby, John; Perez De Leon, Adalberto - Beto

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/24/2021
Publication Date: N/A
Citation: N/A

Interpretive Summary: Cattle fever ticks (CFT) Rhipicephalus microplus and R. annulatus are invasive livestock pests that are endemic to Mexico and invasive along the Texas – Mexico border. Acaricide resistance, alternate wildlife hosts, and pathogenic landscape forming weeds present challenges for sustainable eradication of this pest in the U.S. CFT are the vector for bovine babesiosis, a lethal disease causing high mortality particularly in cattle. Efforts to eradicate CFT from the United States have been successful; however, in recent years, there has been an increase in CFT infestations outside of the Permanent Quarantine Zone in Texas. One of the alternate wildlife hosts for CFT in South Texas are nilgai (Boselaphus tragocamelus), an exotic Asian bovid. Nilgai are highly mobile with large home ranges and are implicated in the spread of CFT, through the landscape. Genetic diversity can determine how well a population responds to pathogens and disease. Populations founded by few individuals, such as nilgai in Texas, often have low genetic diversity, possibly making them more susceptible to diseases. The bodies immune system is responsible for the recognition of diseases and is one of the body’s first line of defense. We characterized genetic diversity of immune system diversity. of nilgai We then compared tick loads to the immune system diversity of nilgai captured in Cameron County, Texas. Nilgai have low genetic diversity compared to other bovid species, with only 7 unique alleles (genes) in the population. Tick loads between individual nilgai varied independent of their genetic diversity at the MHC. Our results suggest that there is no relationship between immune system diversity and tick burdens in South Texas nilgai. Continued research on the genetic diversity and immune response of nilgai will provide information on nilgai-tick interactions to aid in future management decisions.

Technical Abstract: Nilgai antelope (Boselaphus tragocamelus), an exotic bovid species from India, has flourished in South Texas since their introduction in the 1930’s. Nilgai are a suitable host for the Southern Cattle Fever Tick (CFT), Rhipicephalus microplus. The presence of CFT in Texas threatens cattle herds with the transmission of bovine babesiosis, a disease which can be devastating to livestock. Nilgai have the potential to spread ticks during long-distance movements and have been implicated in recent outbreaks of CFT in South Texas. Genetic diversity can determine how well a population responds to pathogens and disease. Populations founded by few individuals, such as nilgai in Texas, often have low genetic diversity, possibly making them more susceptible to pathogens. The major histocompatibility complex (MHC) is responsible for the recognition of pathogens and is one of the body’s first immune defenses. We characterized genetic diversity of the nilgai MHC to index immune system diversity. We then compared tick loads to the immune system diversity of nilgai captured in Cameron County, Texas. Nilgai have low genetic diversity compared to other bovid species, with only 7 unique alleles in the population and a heterozygosity of 61.5%. Tick loads between individual nilgai varied independent of their genetic diversity at the MHC. Our results suggest that there is no relationship between MHC diversity and tick burdens in South Texas nilgai. Continued research on the genetic diversity and immune response of nilgai will provide information on nilgai-tick interactions to aid in future management decisions.