The Virus–Host Interplay in Junín Mammarenavirus Infection

Junín virus (JUNV) belongs to the Arenaviridae family and is the causative agent of Argentine hemorrhagic fever (AHF), a severe human disease endemic to agricultural areas in Argentina. At this moment, there are no effective antiviral therapeutics to battle pathogenic arenaviruses. Cumulative reports from recent years have widely provided information on cellular factors playing key roles during JUNV infection. In this review, we summarize research on host molecular determinants that intervene in the different stages of the viral life cycle: viral entry, replication, assembly and budding. Alongside, we describe JUNV tight interplay with the innate immune system. We also review the development of different reverse genetics systems and their use as tools to study JUNV biology and its close teamwork with the host. Elucidating relevant interactions of the virus with the host cell machinery is highly necessary to better understand the mechanistic basis beyond virus multiplication, disease pathogenesis and viral subversion of the immune response. Altogether, this knowledge becomes essential for identifying potential targets for the rational design of novel antiviral treatments to combat JUNV as well as other pathogenic arenaviruses.     

Experimental Morogoro Virus Infection in Its Natural Host,Mastomys natalensis

Natural hosts of most arenaviruses are rodents. The human-pathogenic Lassa virus and several non-pathogenic arenaviruses such as Morogoro virus (MORV) share the same host species, namely Mastomys natalensis (M. natalensis). In this study, we investigated the history of infection and virus transmission within the natural host population. To this end, we infected M. natalensis at different ages with MORV and measured the health status of the animals, virus load in blood and organs, the development of virus-specific antibodies, and the ability of the infected individuals to transmit the virus. To explore the impact of the lack of evolutionary virus–host adaptation, experiments were also conducted with Mobala virus (MOBV), which does not share M. natalensis as a natural host. Animals infected with MORV up to two weeks after birth developed persistent infection, seroconverted and were able to transmit the virus horizontally. Animals older than two weeks at the time of infection rapidly cleared the virus. In contrast, MOBV-infected neonates neither developed persistent infection nor were able to transmit the virus. In conclusion, we demonstrate that MORV is able to develop persistent infection in its natural host, but only after inoculation shortly after birth. A related arenavirus that is not evolutionarily adapted to M. natalensis is not able to establish persistent infection. Persistently infected animals appear to be important to maintain virus transmission within the host population.     

RNA virus replication depends on enrichment of phosphatidylethanolamine at replication sites in subcellular membranes

Intracellular membranes are critical for replication of positive-strand RNA viruses. To dissect the roles of various lipids, we have developed an artificial phosphatidylethanolamine (PE) vesicle-based Tomato bushy stunt virus (TBSV) replication assay. We demonstrate that the in vitro assembled viral replicase complexes (VRCs) in artificial PE vesicles can support a complete cycle of replication and asymmetrical RNA synthesis, which is a hallmark of (+)-strand RNA viruses. Vesicles containing ∼85% PE and ∼15% additional phospholipids are the most efficient, suggesting that TBSV replicates within membrane microdomains enriched for PE. Accordingly, lipidomics analyses show increased PE levels in yeast surrogate host and plant leaves replicating TBSV. In addition, efficient redistribution of PE leads to enrichment of PE at viral replication sites. Expression of the tombusvirus p33 replication protein in the absence of other viral compounds is sufficient to promote intracellular redistribution of PE. Increased PE level due to deletion of PE methyltransferase in yeast enhances replication of TBSV and other viruses, suggesting that abundant PE in subcellular membranes has a proviral function. In summary, various (+)RNA viruses might subvert PE to build membrane-bound VRCs for robust replication in PE-enriched membrane microdomains.Many steps in the infection cycles of positive-strand RNA viruses, including entry into the cell, replication, virion assembly, and egress, are associated with subcellular membranes (1–4). Therefore, viruses have to interact with different lipids, such as phospholipids and sterols, which affect the biophysical features of membranes, including the fluidity and curvature (5, 6). The subverted cellular membranes could protect the viral RNA from recognition by the host nucleic acid sensors or from destruction by the cellular innate immune system. In addition, membranes facilitate the sequestration of viral and coopted host proteins to increase their local concentrations and promote macromolecular assembly, including formation of the viral replicase complex (VRC) or virion assembly. To optimize viral processes, RNA viruses frequently manipulate lipid composition of various intracellular membranes (6–13). Overall, the interaction between cellular lipids and viral components is emerging as one of the possible targets for antiviral methods against a great number of viruses. Understanding the roles of various lipids in RNA virus infections is important to ultimately control harmful RNA viruses.Among the various lipids, the highly abundant phospholipids are especially targeted by RNA viruses (2). In general, phospholipids likely affect the replication of most RNA viruses, which takes place within membranous structures (1, 3, 4). Accordingly, lipidomics analyses of cells infected with Dengue virus and hepatitis C virus (HCV) (8, 9) revealed enhanced virus-induced lipid biosynthesis, resulting in changes in the global lipid profile of host cells. Also, the less abundant regulatory phosphatidylinositol-4-phosphate (PI4P) was shown to be enriched at sites of enterovirus and HCV replication due to recruitment of cellular lipid kinases (7, 14), suggesting that a microenvironment enriched for PI4P facilitates (+)RNA virus replication. However, our knowledge on the roles of various phospholipids in RNA virus replication is currently incomplete. By using tombusviruses, small model RNA viruses of plants that can replicate in a yeast surrogate host (15), which has the advantage of tolerating large changes in different phospholipid composition, a major role for global phospholipid and sterol biosynthesis, have been revealed (16–18). In this paper, a viral replicase reconstitution assay based on artificial phospholipid vesicles identified the essential role of phosphatidylethanolamine (PE) in replication of Tomato bushy stunt virus (TBSV). It has also been shown that TBSV could recruit and enrich PE to the sites of viral replication in yeast and plant cells. Moreover, genetic changes that either increase or decrease PE levels in yeast greatly stimulated or inhibited TBSV replication, confirming the key role of PE in the formation of TBSV replicase.     

Cellular Lipids—Hijacked Victims of Viruses

Over the millions of years-long co-evolution with their hosts, viruses have evolved plenty of mechanisms through which they are able to escape cellular anti-viral defenses and utilize cellular pathways and organelles for replication and production of infectious virions. In recent years, it has become clear that lipids play an important role during viral replication. Viruses use cellular lipids in a variety of ways throughout their life cycle. They not only physically interact with cellular membranes but also alter cellular lipid metabolic pathways and lipid composition to create an optimal replication environment. This review focuses on examples of how different viruses exploit cellular lipids in different cellular compartments during their life cycles.     

Positive-strand RNA viruses stimulate host phosphatidylcholine synthesis at viral replication sites

All positive-strand RNA viruses reorganize host intracellular membranes to assemble their viral replication complexes (VRCs); however, how these viruses modulate host lipid metabolism to accommodate such membrane proliferation and rearrangements is not well defined. We show that a significantly increased phosphatidylcholine (PC) content is associated with brome mosaic virus (BMV) replication in both natural host barley and alternate host yeast based on a lipidomic analysis. Enhanced PC levels are primarily associated with the perinuclear ER membrane, where BMV replication takes place. More specifically, BMV replication protein 1a interacts with and recruits Cho2p (choline requiring 2), a host enzyme involved in PC synthesis, to the site of viral replication. These results suggest that PC synthesized at the site of VRC assembly, not the transport of existing PC, is responsible for the enhanced accumulation. Blocking PC synthesis by deleting the CHO2 gene resulted in VRCs with wider diameters than those in wild-type cells; however, BMV replication was significantly inhibited, highlighting the critical role of PC in VRC formation and viral replication. We further show that enhanced PC levels also accumulate at the replication sites of hepatitis C virus and poliovirus, revealing a conserved feature among a group of positive-strand RNA viruses. Our work also highlights a potential broad-spectrum antiviral strategy that would disrupt PC synthesis at the sites of viral replication but would not alter cellular processes.All positive-strand RNA viruses [(+)RNA viruses], which include numerous important human, animal, and plant pathogens, share similar strategies for genomic replication. A highly conserved and indispensable feature of their replication is the proliferation and reorganization of host cellular membranes to assemble viral replication complexes (VRCs). Despite this central importance, it is largely unknown how cellular membranes are rearranged by the viral replication proteins and how cellular lipid metabolism is modulated to accommodate membrane proliferation and remodeling.Brome mosaic virus (BMV) serves as a model for understanding VRC formation of (+)RNA viruses (1). BMV is the type member of the plant virus family Bromoviridae and a representative member of the alphavirus-like superfamily, which includes many human, animal, and plant-infecting viruses (2). BMV encodes two replication proteins, 1a and 2a^pol. 2a^pol serves as the replicase, whereas 1a has an N-terminal methyltransferase domain (3, 4) and a C-terminal ATPase/helicase-like domain (5). Together, 1a and 2a^pol are necessary and sufficient for BMV replication. BMV induces vesicular structures in its surrogate host, the yeast Saccharomyces cerevisiae, and its natural host, barley (6, 7). These structures, termed spherules, have been shown to be the VRCs in yeast as 1a, 2a^pol, and nascent viral RNAs reside in the interior of these compartments. Spherules are invaginations of the outer perinuclear endoplasmic reticulum (ER) membrane into the ER lumen and are about 60–80 nm in diameter (6). Remarkably, expression of 1a alone in yeast induces spherule formation (6), which requires 1a’s amphipathic α-helix (1a amino acids 392–407) (8), helix A, and 1a–1a interactions (9, 10). In addition, several host proteins, including membrane-shaping reticulons (RTNs) (11) and an ESCRT (endosomal sorting complex required for transport) component, Snf7p (sucrose nonfermenting7) (12), are recruited by 1a to form spherules.Similar to other (+)RNA viruses, BMV promotes host lipid synthesis and requires balanced lipids for the formation and activity of VRCs. Expression of 1a in yeast induces a ∼30% increase in total fatty acids (FAs) per cell (13). BMV also requires a high level of unsaturated FA (UFA) because a ∼12% decrease of UFAs in the yeast ole1w mutant blocks its replication more than 20-fold (13). In addition, deleting host ACB1 (Acyl-CoA-binding 1) gene results in formation of spherules that are smaller in size but are in greater number than in wild-type (WT) cells (14). ACB1 encodes acyl-CoA binding protein, which binds long-chain fatty acyl-CoAs and is involved in maintaining lipid homeostasis. Supplemented long-chain UFAs largely complement the BMV replication defects in cells lacking ACB1, indicating that the altered lipid composition is primarily responsible for BMV replication defects (14).Cellular membranes are mainly composed of phospholipids, and in particular, phosphatidylcholine (PC) constitutes ∼50% of total phospholipids (15). PC is synthesized via the CDP–DAG (cytidine diphosphate–diacylglycerol) and Kennedy pathways in eukaryotes (16). PC synthesis is significantly enhanced during infection of Dengue virus (DENV) (17), Flock House virus (FHV) (18), and poliovirus (19, 20). A 70% and 35% increase of total PC levels was recorded in DENV-infected mosquito cells (17) and FHV-infected Drosophila cells (18), respectively. At the peak time of poliovirus replication in HeLa cells, a ∼37% increase of PC content was observed after a 30-min chase (19). It was further found that poliovirus promotes the import of FAs, which were subsequently channeled to the viral replication sites. In addition, FAs were mainly incorporated into PCs (20).One critical question based on the aforementioned research is whether the enhanced PC is synthesized in association with the VRCs or elsewhere in cells and subsequently transported into the VRCs. If PC is produced in association with the VRCs, what key enzymes are recruited? We report here that several (+)RNA viruses, including BMV, hepatitis C virus (HCV), and poliovirus, promote significantly enhanced accumulation of PC content at the viral replication sites, revealing a common feature of viral replication among a group of (+)RNA viruses. We further demonstrate that BMV 1a interacts with and redistributes the host enzyme, Cho2p (choline requiring 2), to the viral replication sites. As Cho2p converts phosphatidylethanolamine (PE) to PC in the CDP–DAG pathway, the relocalization of Cho2p suggests the VRC-localized PC synthesis. Deleting CHO2 inhibits BMV replication up to 30-fold and results in formation of spherules that are larger than those of WT cells. This work highlights the importance of PC in VRC formation and the possibility of developing a novel and broad-spectrum antiviral strategy by specifically disrupting PC synthesis at the viral replication sites but not general PC synthesis.     

The Bank Vole (Clethrionomys glareolus)—Small Animal Model for Hepacivirus Infection

Many people worldwide suffer from hepatitis C virus (HCV) infection, which is frequently persistent. The lack of efficient vaccines against HCV and the unavailability of or limited compliance with existing antiviral therapies is problematic for health care systems worldwide. Improved small animal models would support further hepacivirus research, including development of vaccines and novel antivirals. The recent discovery of several mammalian hepaciviruses may facilitate such research. In this study, we demonstrated that bank voles (Clethrionomys glareolus) were susceptible to bank vole-associated Hepacivirus F and Hepacivirus J strains, based on the detection of hepaciviral RNA in 52 of 55 experimentally inoculated voles. In contrast, interferon α/β receptor deficient C57/Bl6 mice were resistant to infection with both bank vole hepaciviruses (BvHVs). The highest viral genome loads in infected voles were detected in the liver, and viral RNA was visualized by in situ hybridization in hepatocytes, confirming a marked hepatotropism. Furthermore, liver lesions in infected voles resembled those of HCV infection in humans. In conclusion, infection with both BvHVs in their natural hosts shares striking similarities to HCV infection in humans and may represent promising small animal models for this important human disease.     

Atomic Interactions and Order–Disorder Transition in FCC-Type FeCoNiAl1−xTix High-Entropy Alloys

Single-phase high-entropy alloys with compositionally disordered elemental arrangements have excellent strength, but show a serious embrittlement effect with increasing strength. Precipitation-hardened high-entropy alloys, such as those strengthened by L1₂-type ordered intermetallics, possess a superior synergy of strength and ductility. In this work, we employ first-principles calculations and thermodynamic simulations to explore the atomic interactions and order–disorder transitions in FeCoNiAl_1−xTi_x high-entropy alloys. Our calculated results indicate that the atomic interactions depend on the atomic size of the alloy components. The thermodynamic stability behaviors of L1₂ binary intermetallics are quite diverse, while their atomic arrangements are short-range in FeCoNiAl_1−xTi_x high-entropy alloys. Moreover, the order–disorder transition temperatures decrease with increasing Ti content in FeCoNiAl_1−xTi_x high-entropy alloys, the characteristics of order–disorder transition from first-principles calculations are in line with experimental observations and CALPHAD simulations. The results of this work provide a technique strategy for proper control of the order–disorder transitions that can be used for further optimizing the microstructure characteristics as well as the mechanical properties of FeCoNiAl_1−xTi_xhigh-entropy alloys.     

High-resolution asymmetric structure of a Fab–virus complex reveals overlap with the receptor binding site

Canine parvovirus is an important pathogen causing severe diseases in dogs, including acute hemorrhagic enteritis, myocarditis, and cerebellar disease. Overlap on the surface of parvovirus capsids between the antigenic epitope and the receptor binding site has contributed to cross-species transmission, giving rise to closely related variants. It has been shown that Mab 14 strongly binds and neutralizes canine but not feline parvovirus, suggesting this antigenic site also controls species-specific receptor binding. To visualize the conformational epitope at high resolution, we solved the cryogenic electron microscopy (cryo-EM) structure of the Fab–virus complex. We also created custom software, Icosahedral Subparticle Extraction and Correlated Classification, to solve a Fab–virus complex with only a few Fab bound per capsid and visualize local structures of the Fab-bound and -unbound antigenic sites extracted from the same complex map. Our results identified the antigenic epitope that had significant overlap with the receptor binding site, and the structures revealed that binding of Fab induced conformational changes to the virus. We were also able to assign the order and position of attached Fabs to allow assessment of complementarity between the Fabs bound to different positions. This approach therefore provides a method for using cryo-EM to investigate complementarity of antibody binding.

Canine parvovirus (CPV) emerged as a host range variant virus in the mid-1970s, subsequently causing a pandemic of disease in dogs during 1978 (1, 2). Since that time, multiple variants have emerged with additional mutations in the viral capsid (3, 4). Extensive genetic and biochemical studies have shown that specific mutations displayed on or near the capsid surface alter binding to the host receptor, transferrin receptor type-1 (TfR). Since the specific host ranges of canine and feline parvoviruses are primarily controlled by the ability of the virus to bind TfR, changes in the binding site alter the ability of the virus to infect different hosts (3, 5, 6).The virus capsid is highly antigenic, and an infection elicits many different host antibodies, which recognize specific structures on the surface of the virus that are primarily displayed as conformational epitopes. Most antibodies efficiently neutralize virus as IgGs, whereas they vary in their neutralization abilities when tested as Fabs (7, 8). In a number of cases, selection of antibody escape mutations by antibodies also selects for host range variation in the viruses, and conversely, selection for host range variation alters the antigenic structure recognized by specific antibodies (6, 9, 10). Although some of these changes appear to result from overlap of the receptor and antibody binding sites, it is still not clear how different selections operate in the natural evolution of the viruses. Understanding the mechanisms of host recognition and the dynamics of the binding by antibodies and receptors would provide insight into the connections between antigenic and host range variation, enabling us to predict the ability of a given virus capsid to change hosts or to escape host immunity. The coordinated overlap between antibody and receptor binding has also been seen in other viruses, including SARS-CoV-2 and influenza viruses (11–13).CPV has a small, 26-nm diameter, T = 1 icosahedral capsid that packages a single-stranded DNA (ssDNA) genome of about 5,000 bases. The capsid shell is composed of VP2 (∼90%) and VP1 (∼10%), which are generated by differential messenger RNA splicing events so that the entire sequence of VP2 is also contained within VP1. Both proteins fold into the same eight-stranded, antiparallel β-barrel structure, where the β-strands are connected by loops that make up the surface features of the capsid. A raised region known as the threefold spike surrounds each icosahedral threefold axis and contains most of the antigenic structures recognized by different antibodies (14, 15). MAb 14 is a mouse monoclonal antibody generated against CPV capsids that has particularly interesting properties. MAb 14 binding, hemagglutination inhibition properties, and neutralization are all virus-strain specific, and it bound with significantly higher affinity to CPV capsids than to the closely related but host range variant–virus that infected cats, feline panleukopenia virus (FPV) (16–18). The virus-specific binding of MAb is controlled by the capsid surface residue 93, which is Lys in FPV and Asn in CPV (19–21). In addition to antibody recognition, residue 93 also controls canine host range, since Asn93 allows binding to canine TfR and infection of canine cells, whereas Lys93 in the equivalent position on the FPV capsid prevents both of these processes (20).Despite the central role of antibodies in protecting animals against virus infections and allowing recovery from disease, in many cases, we still lack a detailed understanding of epitope characteristics, the dynamics of binding processes, and the viral neutralization mechanisms. Previous X-ray crystallography and cryo-electron microscopy (cryo-EM) structures include the Fab of MAb 14 (Fab 14), CPV and FPV capsids, and a Fab 14–CPV capsid complex at moderate resolution of 12.5 Å (Protein Data Bank [PDB] IDs: 2CAS, 1C8F, 3IY0, and 3GK8) (18, 22, 23). Crystal structures of Fab 14, CPV, and FPV fitted into the cryo-EM map of Fab–virus complex have allowed us to predict protein interactions in the binding interface (18). Although this was the most rigorous approach at the time, the resulting pseudoatomic structure based on the fitting did not explain why variation in residue 93 controlled Fab binding, identify likely mechanisms of antibody neutralization, or explain how the minor changes in the site also affect TfR binding. Recent technological advances in cryo-EM now allow us to solve Fab–virus structures at high enough resolution to build atomic models directly into the density map for identifying interactions unambiguously.The binding and occupancy of Fabs on the CPV capsid have also been determined previously using charge detection mass spectrometry, which revealed that some of the tested monoclonal antibody–derived Fabs, including Fab 14, could fully occupy all 60 epitopes of the capsid but with some differences in the kinetics of attachment (24). Incubating with excess Fab molecules to occupy all icosahedrally equivalent sites on capsids has long been the preferred cryo-EM structural approach since this allows icosahedral symmetry averaging to be imposed during the reconstruction process for maximizing resolution (18, 25, 26). However, there are few other studies confirming the occupancies of Fabs on viral capsids, and the larger IgG likely does not saturate the entire surface of the capsid so that an undersaturated capsid (with fewer than 60 bound Fab in the case of parvoviruses) would more closely mimic the physiologically relevant complexes. Solving such an asymmetric structure at atomic resolution is now possible due to advances in cryo-EM and the reconstruction approaches.Here, we define an atomic model of Fab 14 bound to the capsid of CPV based on cryo-EM of the complex and examine the functional mechanisms that affect binding by testing antibody mutants. Of the two data sets used to reconstruct Fab–virus complex maps, one had close to complete occupancy of the 60 capsid epitopes, whereas the other had an average of 10 Fabs bound per capsid. These data were used initially to solve the icosahedrally averaged structures of fully Fab-occupied and partially Fab-occupied complexes to resolutions of 3.2 and 2.3 Å, respectively. An asymmetric, partially Fab-occupied virus map calculated with local reconstruction approaches attained 2.4-Å global resolution and revealed the Fab-occupied and unoccupied sites on the same virus capsid. These structures allowed unambiguous identification of residues and side chains involved in the Fab–virus binding interface and also revealed local conformational changes in the antibody binding site induced by Fab binding. The partial occupancy of the capsids by Fab provided an opportunity to develop an innovative algorithm to test for complementarity of Fab binding to different positions on the capsid. Notably, it was the asymmetric approach and not the traditional icosahedrally averaged reconstruction that revealed the details of antibody binding.     

Targeted Profiling of Immunological Genes during Norovirus Replication in Human Intestinal Enteroids

Norovirus is the leading cause of acute gastroenteritis worldwide. The pathogenesis of norovirus and the induced immune response remain poorly understood due to the lack of a robust virus culture system. The monolayers of two secretor-positive Chinese human intestinal enteroid (HIE) lines were challenged with two norovirus pandemic GII.4 Sydney strains. Norovirus RNA replication in supernatants and cell lysates were quantified by RT-qPCR. RNA expression levels of immune-related genes were profiled using PCR arrays. The secreted protein levels of shortlisted upregulated genes were measured in supernatants using analyte-specific enzyme-linked immunosorbent assay (ELISA). Productive norovirus replications were achieved in three (75%) out of four inoculations. The two most upregulated immune-related genes were CXCL10 (93-folds) and IFI44L (580-folds). Gene expressions of CXCL10 and IFI44L were positively correlated with the level of norovirus RNA replication (CXCL10: Spearman’s r = 0.779, p < 0.05; IFI44L: r = 0.881, p < 0.01). The higher level of secreted CXCL10 and IFI44L proteins confirmed their elevated gene expression. The two genes have been reported to be upregulated in norovirus volunteer challenges and natural human infections by other viruses. Our data suggested that HIE could mimic the innate immune response elicited in natural norovirus infection and, therefore, could serve as an experimental model for future virus-host interaction and antiviral studies.     

Deconstructing the Phage–Bacterial Biofilm Interaction as a Basis to Establish New Antibiofilm Strategies

The bacterial biofilm constitutes a complex environment that endows the bacterial community within with an ability to cope with biotic and abiotic stresses. Considering the interaction with bacterial viruses, these biofilms contain intrinsic defense mechanisms that protect against phage predation; these mechanisms are driven by physical, structural, and metabolic properties or governed by environment-induced mutations and bacterial diversity. In this regard, horizontal gene transfer can also be a driver of biofilm diversity and some (pro)phages can function as temporary allies in biofilm development. Conversely, as bacterial predators, phages have developed counter mechanisms to overcome the biofilm barrier. We highlight how these natural systems have previously inspired new antibiofilm design strategies, e.g., by utilizing exopolysaccharide degrading enzymes and peptidoglycan hydrolases. Next, we propose new potential approaches including phage-encoded DNases to target extracellular DNA, as well as phage-mediated inhibitors of cellular communication; these examples illustrate the relevance and importance of research aiming to elucidate novel antibiofilm mechanisms contained within the vast set of unknown ORFs from phages.     

Manipulation of Host Microtubule Networks by Viral Microtubule-Associated Proteins

Diverse DNA and RNA viruses utilize cytoskeletal networks to efficiently enter, replicate, and exit the host cell, while evading host immune responses. It is well established that the microtubule (MT) network is commonly hijacked by viruses to traffic to sites of replication after entry and to promote egress from the cell. However, mounting evidence suggests that the MT network is also a key regulator of host immune responses to infection. At the same time, viruses have acquired mechanisms to manipulate and/or usurp MT networks to evade these immune responses. Central to most interactions of viruses with the MT network are virally encoded microtubule-associated proteins (MAPs) that bind to MTs directly or indirectly. These MAPs associate with MTs and other viral or cellular MAPs to regulate various aspects of the MT network, including MT dynamics, MT-dependent transport via motor proteins such as kinesins and dyneins, and MT-dependent regulation of innate immune responses. In this review, we examine how viral MAP interactions with the MT network facilitate viral replication and immune evasion.