# Characterisation of Cell-Mediated Immunity Against Bovine Alphaherpesvirus 1 (BoAHV-1) in Calves

## TL;DR

This study examines how calves' immune systems respond to BoAHV-1 infection, revealing key immune changes that could help improve vaccines.

## Contribution

The study provides new insights into the early immune response dynamics and cytokine profiles in calves infected with BoAHV-1.

## Key findings

- Infection caused initial immunosuppression with reduced αβ and γδ-T cells.
- Monocyte recruitment and elevated MIP-1β, IFN-γ, and IL-10 levels were linked to recovery from infection.
- Early immune changes suggest a shift toward protective immunity following initial suppression.

## Abstract

Background: Bovine alphaherpesvirus 1 (BoAHV-1) is a major respiratory and reproductive pathogen in cattle worldwide. Both innate and adaptive immune responses contribute to protection against this virus; however, virus-host interactions remain partly undefined. In this study, the impact of BoAHV-1 infection on calves’ immune responses was investigated in detail. Methods: Six calves were intranasally infected with wild-type BoAHV-1, and blood samples were collected longitudinally. Leukocyte subset dynamics were assessed by complete haematological assay and flow cytometry, while multiplex ELISA was used to quantify serum levels of ten cytokines. For each parameter, post-infection values (days 2, 4, 8, 10, and 14) were compared with pre-infection baseline values (day 0). Results: Infection induced an initial phase of immunosuppression, reflected by decreased circulating αβ and γδ-T cells. However, infected animals rapidly developed a protective immune response, characterised by increased circulating classical and intermediate monocytes and elevated levels of the related chemokine MIP-1β. Early post-infection, rises in serum IFN-γ and IL-10 were also detected. Conclusions: Our data suggest that monocyte recruitment and increased serum levels of IFN-γ and IL-10 are positively associated with the ability to overcome infection. A better understanding of the immunopathogenic mechanisms underlying BoAHV-1 infection will support the development of more effective vaccines against this virus.