Human cytomegalovirus (HCMV) manipulates cellular processes associated with secretory pathways within an infected cell to facilitate efficient viral replication. However, little is known about how HCMV infection alters the surrounding cellular environment to promote virus spread to uninfected cells. Extracellular vesicles (EVs) are key signaling molecules that are commonly altered in numerous disease states. Previous reports have shown that viruses commonly alter EVs, which can significantly impact infection. This study finds that HCMV modulates EV biogenesis machinery through upregulation of the endosomal sorting complex required for transport (ESCRT) proteins. This regulation appears to increase the activity of EV biogenesis, since HCMV-infected fibroblasts have increased vesicle release and altered vesicle size compared to EVs from uninfected cells. EVs generated through ESCRT-independent pathways are also beneficial to virus spread in fibroblasts, as treatment with the EV inhibitor GW4869 slowed the efficciency of virus spread to uninfected cells. This finding defines a new layer of host manipulation induced by HCMV infection that leads to enhanced virus spread.Rabbits are pivotal domestic animals for both the economy and as an animal model for human diseases. A large number of rabbits have been infected by rabbit hemorrhagic disease virus (RHDV) in natural and artificial pandemics in the past. Differences in presentation of antigenic peptides by polymorphic major histocompatibility complex (MHC) molecules to T-cell receptors (TCR) on T lymphocytes are associated with viral clearance in mammals. Herein, we screened and identified a series of peptides derived from RHDV binding to the rabbit MHC class I molecule, RLA-A1. The small, hydrophobic B and F pockets of RLA-A1 capture a peptide motif analogous to that recognized by human class I molecule HLA-A*0201, with more restricted aliphatic anchors at P2 and PΩ positions. Meanwhile, the rabbit molecule is featured with an uncommon residue combination of Gly53, Val55 and Glu56, making the 310 helix and the loop between the 310 and α1 helices closer to the α2 helix. A wider A pocket in RLA-A1 can induce a special conformaHC class I assembly. Our results provide new insights into MHC class I molecule assembly and peptide presentation of domestic mammals. Furthermore, these data also broaden our knowledge on T-cell immunity in rabbits and may also provide useful information for vaccine development to prevent infectious diseases in rabbits.Porcine reproductive and respiratory syndrome (PRRS), caused by PRRS virus (PRRSV), has led to enormous economic losses in global swine industry. Infection by PRRSV is previously shown to be via low pH-dependent clathrin-mediated endocytosis (CME) and CD163 functions as an essential receptor during viral infection. Despite much research focusing on it, PRRSV infection remains to be fully elucidated. In this study, we demonstrated that PRRSV externalized phosphatidylserine (PS) on the envelope as viral apoptotic mimicry, and infected host cells through T-cell immunoglobulin and mucin domain (TIM)-induced and CD163-involved macropinocytosis as an alternative pathway. In detail, we identified that PS receptor (PSR) TIM-1/4 recognized and interacted with PRRSV as viral apoptotic mimicry and subsequently induced macropinocytosis by the downstream Rho GTPases Rac1, cell division control protein 42 (Cdc42) and p21-activated kinase 1 (Pak1). Altogether these results expand our knowledge of PRRSV infection, which will support implications for prevention and control of PRRS.IMPORTANCE PRRS has caused huge economic losses to pig farming worldwide. Its causative agent, PRRSV, infects host cells through low pH-dependent CME and CD163 is indispensable during the process. Whether there exist alternative infection pathways for PRRSV arouses our interest. Here, we found that PRRSV exposed PS on its envelope and disguised as apoptotic debris. The PSR TIM-1/4 recognized PRRSV and induced the downstream signaling pathway to mediate viral infection via CD163-dependent macropinocytosis. The current work deepens our understanding of PRRSV infection, and provides clues for the development of drugs and vaccines against the virus.The human adenovirus (HAdV) protein IX (pIX) is a minor component of the capsid that acts in part to stabilize the hexon-hexon interactions within the mature capsid. Virions lacking pIX have a reduced DNA packaging capacity and exhibit thermal instability. More recently, pIX has been developed as a platform for presentation of large polypeptides, such as fluorescent proteins or large targeting ligands, on the viral capsid. It is not known if such modifications affect the natural ability of pIX to stabilize the HAdV virion. In this study, we show that addition of large polypeptides to pIX does not alter the natural stability of virions containing sub-wildtype sized genomes. However, similar virions containing wildtype sized genomes tend to genetically rearrange, likely due to selective pressure caused by virion instability as a result of compromised pIX function.IMPORTANCE Human adenovirus (HAdV) capsid protein IX (pIX) is involved in stabilizing the virion, but has also been developed as a platform for presentation of various polypeptides on the surface of the virion. Whether such modifications affect the ability of pIX to stabilize the virion is unknown. We show that addition of large polypeptides to pIX can reduce both the DNA packaging capacity and heat stability of the virion, which provides important guidance for the design of pIX-modified vectors.Hazara nairovirus (HAZV) is a member of the Nairoviridae family within the Bunyavirales order, and closely-related to Crimean-Congo hemorrhagic fever virus that is responsible for severe and fatal human disease. The HAZV genome comprises three segments of negative sense RNA named S, M and L, with non-translated regions (NTRs) flanking a single open reading frame. NTR sequences regulate RNA synthesis, and by analogy with other segmented negative sense RNA viruses, may direct activities such as virus assembly and innate immune modulation. read more The terminal-proximal nucleotides of 3′ and 5′ NTRs exhibit extensive terminal complementarity; the first eleven nucleotides are strictly conserved and form promoter element (PE) 1, with adjacent segment-specific nucleotides forming PE2. To explore the functionality of NTR nucleotides within the context of the nairovirus multiplication cycle, we designed infectious HAZV mutants bearing successive deletions throughout both S segment NTRs. Fitness of rescued viruses was assessed in single-step and multi-step growth, which revealed the 3′ NTR was highly tolerant to change whereas several deletions of centrally-located nucleotides within the 5′ NTR led to significantly reduced growth, indicative of functional disruption.