Lipid droplets are potentially involved in bovine alphaherpesvirus 1 productive infection partially via stabilization of virion-associated proteins

Bovine alphaherpesvirus 1 (BoAHV-1) is one of the most important viruses that infects cattle and leads to significant economic losses to cattle industry. We have recently reported that both carnitine palmitoyl-transferase 1 A (CPT1A), a rate-limiting enzyme of mitochondrial fatty acid β-oxidation, and the lipogenic enzyme fatty acid synthase (FASN) are involved in viral productive Infection. Excessive fatty acids are typically re-esterified into triacylglycerol (TAG), which are then deposited into lipid droplets (LDs), the primary form of lipid storage in cells. TAG Acyltransferase 1 (DGAT1) and DGAT2 are key Enzymes involved in TAG synthesis, while adipose triglyceride Lipase (ATGL) is a key enzyme involved in breakdown of TAG stored in LDs. To further reveal the roles of fatty acid played in BoAHV-1 life cycles, we investigated the interplay between LDs and viral Infection both in vivo and in vitro. Here, we found that the viral lytic Infection in bovine trigeminal ganglia (TG) neurons increased perilipin 2 (PLIN2) protein levels, indicative of an increase in LDs. Similarly, viral productive Infection in bovine kidney (MDBK) cells increased LD accumulation, as determined using the lipophilic dye BODIPY493/503. Although viral Infection differentially altered the expression of ATGL, DGAT1, and DGAT2, the consistently reduced expression of ATGL both in vivo and in vitro would be expected to decreased lipolysis and consequently the decreased LD degradation. Interestingly, we observed that a proportion of LDs co-localize well with virion-associated proteins, such as viral protein gD, and chemical inhibition of LD accumulation reduced viral productive Infection in MDBK cells, which was partially attributed to the reduced levels of virion-associated proteins. Taken together, we provide an evidence that LDs may facilitate BoAHV-1 productive Infection both in vivo and in vitro.