Protein Composition of the Bovine Herpesvirus 1.1 Virion

Abstract

Bovine herpesvirus (BoHV) type 1 is an important agricultural pathogen that infects cattle and other ruminants worldwide. Acute infection of the oro-respiratory tract leads to immune suppression and allows commensal bacteria to infect an otherwise healthy lower respiratory tract. This condition is known as the Bovine Respiratory Disease (BRD). BoHV-1 latently infects the host for life and periodical stress events re-initiate BRD, translating into high morbidity and large economic losses. To gain a better understanding of the biology of BoHV-1 and the disease it causes, we elucidated the protein composition of extracellular virions using liquid chromatography-mass spectrometry analysis. We detected 33 viral proteins, including the expected proteins of the nucleocapsid and envelope as well as other regulatory proteins present in the viral tegument. In addition to viral proteins, we have also identified packaged proteins of host origin. This constitutes the first proteomic characterization of the BoHV virion.

Keywords: bovine herpesvirus; proteomics; virion.

Figure 1

Visualization of purified Bovine herpesvirus type 1.1 virions at 80,000× magnification using the transmission electron microscope and negative staining. The black bar represents 200 nanometers.

Figure 2

Western blot analysis of proteins found in the virion. (A) Twenty micrograms of whole cell lysates of uninfected (mock) and infected cells were separated by SDSPAGE next to 10 micrograms of purified virion extracts. Each blot was probed with the antibody indicated on the left to document its presence in purified virions (B) Identical gel as in A was silver stained instead.

Figure 3

Diagram of the BoHV-1.1 viral particle, representing the viral proteins detected in this study. The relative abundance was estimated based on emPAI scores [39] (Table 1) and are presented on a gray-scale that correlates with abundance (darker = more abundant). emPAI values < 0.3 (white); 0.3–1 (light gray); 1–2 (dark gray) and >2 (black). The diagram was inspired by those of past work [30,31,40].