Step 1: Understanding the Concept:
Bovine Herpesvirus-1 (BoHV-1) is a major viral pathogen of cattle belonging to the family *Herpesviridae*.
It is associated with various clinical syndromes, including respiratory tract disease, genital tract disease, and reproductive failures.
Like other herpesviruses, BoHV-1 establishes lifelong latent infections in the nervous system of recovered animals.
Step 2: Detailed Explanation:
Let us analyze each statement to determine its accuracy.
Statement (A) is correct. BoHV-1 is the primary causative agent of Infectious Bovine Rhinotracheitis (IBR), which is characterized by severe inflammation of the upper respiratory tract, fever, nasal discharge, and "red nose" syndrome.
Statement (B) is correct. In addition to respiratory disease, venereal transmission of BoHV-1 causes Infectious Pustular Vulvovaginitis (IPV) in cows and Infectious Pustular Balanoposthitis (IPB) in bulls.
Statement (C) is correct. Following primary infection, the virus travels up sensory nerve fibers to establish lifelong latency within the sensory ganglia (such as the trigeminal ganglia for respiratory infections and sacral ganglia for genital infections).
During periods of physiological stress, transport, calving, or immunosuppression (e.g., corticosteroid therapy), the virus undergoes recrudescence, replicates, and is shed in secretions, causing new clinical disease or transmission.
Statement (D) is incorrect. BoHV-1 is a highly significant cause of reproductive loss and abortion in pregnant cattle.
Systemic viral infection during pregnancy leads to viremia, transplacental infection of the fetus, fetal hepatic necrosis, and subsequent abortion, typically occurring between the fifth and eighth months of gestation.
Therefore, the statement that BoHV-1 does not affect pregnant animals is incorrect.
Step 3: Final Answer:
The correct option is (D).