A Serosurvey for Ruminant Pestivirus Exposure Conducted Using Sera From Stray Mexico Origin Cattle Captured Crossing Into Southern Texas.

Rohana P Dassanayake,Fernando V Bauermann,Glen A Scoles,Denise Bonilla,Shollie M Falkenberg

doi:10.3389/fvets.2022.821247

Abstract

The US Department of Agriculture (USDA), Animal Plant Health Inspection Service (APHIS), Cattle Fever Tick Eradication Program (CFTEP) monitor a quarantine zone along the Texas border to prevent the introduction of stray livestock carrying cattle fever ticks entering the United States from Mexico. Stray cattle collected by CFTEP are checked for ticks and several infectious disease-causing pathogens, but not for bovine viral diarrhea virus (BVDV). BVDV is one of the most economically impactful viruses affecting US cattle producers. BVDV is present in all parts of the world, but it has been demonstrated that another distantly related pestivirus, HoBi-like pestivirus (HoBiPev), can also cause BVD. To date, HoBiPev has not been detected in the United States, but is commonly found in Brazil, and sporadically in Europe and Asia. The objective of the current study was to evaluate the seroprevalence of pestiviruses, with a specific focus on HoBiPev, in stray cattle. Virus neutralization (VN) assay was used to determine seroprevalence (or antibody titers) of BVDV-1, BVDV-2, and HoBiPev. Approximately 50% (67 of 134) of the samples were seropositive for pestiviruses; all 67 positive samples were positive (50%) for BVDV-1, 66 samples of the 67 were positive (49.3%) for BVDV-2, and the same 66 samples of the 67 were also positive (49.3%) for HoBiPev. Due to the antigenic cross-reactivity among Pestiviruses, the comparative antibody against each pestivirus was calculated from all VN-positive samples. Titers were clearly higher against BVDV-1, and only one sample had a titer clearly higher against BVDV-2. No sample had an antibody titer higher for HoBiPev, and while this does not prove the absence of HoBiPev, it does provide evidence that the prevalence of HoBiPev is less predominant than BVDV-1. Additionally, data from these samples provide evidence on the susceptibility of animals that may enter into the United States, with ~50% of the animals seronegative for bovine pestiviruses. This cattle population provides a unique opportunity to evaluate and monitor changes in seroprevalence of economically important cattle diseases affecting the cattle industry.

Highlights

The US cattle industry was devastated in the beginning of the 20th century by bovine babesiosis, known as cattle fever or Texas cattle fever
50.7% had no neutralizing titer for any tested pestivirus, whereas bovine viral diarrhea virus (BVDV)-1a titer predominated in 43.3% of the samples and BVDV-2 in 0.7% of the samples
Serologic results from stray Mexico cattle suggest that half of these cattle have been exposed to bovine pestiviruses

Summary

Introduction

The US cattle industry was devastated in the beginning of the 20th century by bovine babesiosis, known as cattle fever or Texas cattle fever. The United States Department of Agriculture (USDA), Animal and Plant Health Inspection Service (APHIS), and Cattle Fever Tick Eradication Program (CFTEP) monitor the premises adjacent to the Mexico border in counties that comprise the permanent quarantine zone for detection and management of stray cattle [3] When observed, these cattle are apprehended and evaluated for a variety of pathogens similar to that of legally imported cattle. The numbers of stray cattle apprehended may be influenced by a variety of factors, such as violence along the border, environmental effects (drought, weather patterns, temperature, etc.), river levels, and economic or financial hardships [4] Monitoring this population of stray cattle provides a unique opportunity to evaluate the risk of introducing pathogens that potentially pose a threat to the US cattle industry

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