Multiprotein complexes are key determinants of Golgi apparatus structure and its capacity for intracellular transport and glycoprotein modification. Three complexes that have previously been partially characterized include (a) the Golgi transport complex (GTC), identified in an in vitro membrane transport assay, (b) the ldlCp complex, identified in analyses of CHO cell mutants with defects in Golgi-associated glycosylation reactions, and (c) the mammalian Sec34 complex, identified by homology to yeast Sec34p, implicated in vesicular transport. We show that these three complexes are identical and rename them the conserved oligomeric Golgi (COG) complex. The COG complex comprises four previously characterized proteins (Cog1/ldlBp, Cog2/ldlCp, Cog3/Sec34, and Cog5/GTC-90), three homologues of yeast Sec34/35 complex subunits (Cog4, -6, and -8), and a previously unidentified Golgi-associated protein (Cog7). EM of ldlB and ldlC mutants established that COG is required for normal Golgi morphology. “Deep etch” EM of purified COG revealed an ∼37-nm-long structure comprised of two similarly sized globular domains connected by smaller extensions. Consideration of biochemical and genetic data for mammalian COG and its yeast homologue suggests a model for the subunit distribution within this complex, which plays critical roles in Golgi structure and function.

We describe two distinct modes of neuroinvasion and lethality after murine flank inoculation with virulent and attenuated strains of pseudorabies virus (PRV). Mice infected with virulent (e.g., PRV-Becker, PRVKaplan, or PRV-NIA3) strains self-mutilate their flank skin in response to virally induced pruritus, die rapidly with no identifiable symptoms of central nervous system (CNS) infection such as behavioral abnormalities, and have little infectious virus or viral antigen in the brain. In distinct contrast, animals infected with an attenuated PRV vaccine strain (PRV-Bartha) survive approximately three times longer than wild-type PRVinfected animals, exhibit severe CNS abnormalities, and have an abundance of infectious virus in the brain at the time of death. Interestingly, these animals have no skin lesions and do not appear pruritic at any time during infection. The severe pruritus and relatively earlier time until death induced by wild-type PRV infection may reflect the peripheral nervous system (PNS) and immune responses to infection rather than a fatal, virally induced CNS pathology. Based on previously characterized afferent (sensory) and efferent (motor) neuronal pathways that innervate the skin, we deduced that wild-type virulent strains transit through the PNS via both afferent and efferent routes, whereas PRV-Bartha travels by only efferent routes in the PNS en route to the brain.Pseudorabies virus (PRV), a swine alphaherpesvirus, is a member of the alphaherpesvirus subfamily, including human and animal pathogens such as varicella-zoster virus, herpes simplex virus type 1 (HSV-1) and HSV-2, bovine herpesvirus types 1 and 5, and equine herpesviruses types 1 and 4 (23). Although the natural hosts of PRV are adult swine, PRV is pantropic, infecting avian embryos and a wide range of mammalian species, with the notable exceptions of humans and other higher-order species of nonhuman primates.PRV routinely establishes a latent infection in PNS ganglia of adult swine and yet rarely invades the central nervous systems (CNS) of these animals (8). Viral spread between adult swine occurs primarily via direct mucosal contact. Common sequelae of wild-type PRV infection include respiratory disease, weight loss, and infertility in pregnant gilts and sows (31). In contrast, PRV infection is lethal in neonatal piglets and in nonnative hosts such as cows, dogs, rodents, and other susceptible animals. In these animals, infection induces severe, uncontrollable pruritus (itchiness), culminating in frantic selfmutilating behavior historically described as "mad itch." Death ensues within days of infection with virulent strains of PRV. The cause of death of these animals has traditionally been ascribed to fatal encephalitis.Adult swine infected with live, attenuated vaccine strains such as PRV-Bartha typically exhibit few, if any, symptoms of infection. In addition, most attenuated PRV strains are significantly less virulent in nonnative hosts such as rodents (8). Despite the attenuated phenotype, PRV-Bartha remains neuroinvas...

Herpes simplex virus type 1 (HSV-1) produces oral lesions, encephalitis, keratitis, and severe infections in the immunocompromised host. HSV-1 is almost as common as HSV-2 in causing first episodes of genital herpes, a disease that is associated with an increased risk of human immunodeficiency virus acquisition and transmission. No approved vaccines are currently available to protect against HSV-1 or HSV-2 infection. We developed a novel HSV vaccine strategy that uses a replication-competent strain of HSV-1, NS-gEnull, which has a defect in anterograde and retrograde directional spread and cell-to-cell spread. Following scratch inoculation on the mouse flank, NS-gEnull replicated at the site of inoculation without causing disease. Importantly, the vaccine strain was not isolated from dorsal root ganglia (DRG). We used the flank model to challenge vaccinated mice and demonstrated that NS-gEnull was highly protective against wild-type HSV-1. The challenge virus replicated to low titers at the site of inoculation; therefore, the vaccine strain did not provide sterilizing immunity. Nevertheless, challenge by HSV-1 or HSV-2 resulted in less-severe disease at the inoculation site, and vaccinated mice were totally protected against zosteriform disease and death. After HSV-1 challenge, latent virus was recovered by DRG explant cocultures from <10% of vaccinated mice compared with 100% of mock-vaccinated mice. The vaccine provided protection against disease and death after intravaginal challenge and markedly lowered the titers of the challenge virus in the vagina. Therefore, the HSV-1 gEnull strain is an excellent candidate for further vaccine development.Herpes simplex virus type 1 (HSV-1) and HSV-2 are closely related alphaherpesviruses that cause lifelong infections for which there is no cure. HSV-1 generally causes oral lesions, while HSV-2 remains the most common cause of genital ulcers; however, the epidemiology of genital herpes is changing in that 35% to 50% of new cases are now caused by HSV-1 (40). The life cycles of HSV-1 and HSV-2 are similar. After replication in epithelial cells, HSV enters local sensory nerve endings of the peripheral nervous system and spreads in a retrograde direction to neuronal cell bodies. HSV then spreads to adjacent neurons in ganglia, where a lifelong latent infection is established (43). During recurrences, HSV travels in the anterograde direction along axon fibers from infected neuronal cell bodies to skin or mucosal surfaces, resulting in asymptomatic virus shedding or symptomatic vesicles and ulcers.More than 70% of people in the United States are seropositive for HSV-1 or HSV-2 by age 49, with HSV-1 being more prevalent (44). Worldwide, the prevalence of infection is generally higher than in the United States (34). Complications of HSV infection include meningitis, encephalitis, esophagitis, disseminated disease in neonates and immunocompromised individuals, and herpes stromal keratitis, which can lead to blindness. Additionally, HSV-2 infection increases human immunodeficienc...

The pseudorabies virus (PRV) UL54 homologs are important multifunctional proteins with roles in shutoff of host protein synthesis, transactivation of virus and cellular genes, and regulation of splicing and translation. Here we describe the first genetic characterization of UL54. We constructed UL54 null mutations in a PRV bacterial artificial chromosome using sugar suicide and Red allele exchange systems. Surprisingly, UL54 is dispensable for growth in tissue culture but exhibits a small-plaque phenotype that can be complemented in trans by both the herpes simplex virus type 1 ICP27 and varicella-zoster virus open reading frame 4 proteins. Deletion of UL54 in the virus vJS⌬54 had no effect on the ability of the virus to shut off host cell protein synthesis but did affect virus gene expression. The glycoprotein gC accumulated to lower levels in cells infected with vJS⌬54 compared to those infected with wild-type virus, while gK levels were undetectable. Other late gene products, gB, gE, and Us9, accumulated to higher levels than those seen in cells infected with wild-type virus in a multiplicity-dependent manner. DNA replication is also reduced in cells infected with vJS⌬54. UL54 appears to regulate UL53 and UL52 at the transcriptional level as their respective RNAs are decreased in cells infected with vJS⌬54. Interestingly, vJS⌬54 is highly attenuated in a mouse model of PRV infection. Animals infected with vJS⌬54 survive twice as long as animals infected with wild-type virus, and this results in delayed accumulation of virus-specific antigens in skin, dorsal root ganglia, and spinal cord tissues.

How do protein-transporting vesicles, which bud from the endoplasmic reticulum (ER), specifically dock to, and fuse with, the Golgi apparatus? In their Perspective, Brittle and Waters discuss new work (Allan et al.) suggesting that some vesicle-associated docking and fusion proteins are "programmed" during vesicle budding from the ER and direct downstream events that occur during fusion of these transport vesicles with the membranes of the Golgi.