Bovine respiratory tract disease is a multi-factorial disease complex involving several viruses and bacteria. Viruses that play prominent roles in causing the bovine respiratory disease complex include bovine herpesvirus-1, bovine respiratory syncytial virus, bovine viral diarrhea virus and parinfluenza-3 virus. Bacteria that play prominent roles in this disease complex are Mannheimia haemolytica and Mycoplasma bovis. Other bacteria that infect the bovine respiratory tract of cattle are Histophilus (Haemophilus) somni and Pasteurella multocida. Frequently, severe respiratory tract disease in cattle is associated with concurrent infections of these pathogens. Like other pathogens, the viral and bacterial pathogens of this disease complex have co-evolved with their hosts over millions of years. As much as the hosts have diversified and fine-tuned the components of their immune system, the pathogens have also evolved diverse and sophisticated strategies to evade the host immune responses. These pathogens have developed intricate mechanisms to thwart both the innate and adaptive arms of the immune responses of their hosts. This review presents an overview of the strategies by which the pathogens suppress host immune responses, as well as the strategies by which the pathogens modify themselves or their locations in the host to evade host immune responses. These immune evasion strategies likely contribute to the failure of currently-available vaccines to provide complete protection to cattle against these pathogens.

Recent advances in cell-free synthetic biology have given rise to gene circuit-based sensors with the potential to provide decentralized and low-cost molecular diagnostics. However, it remains a challenge to deliver this sensing capacity into the hands of users in a practical manner. Here, we leverage the glucose meter, one of the most widely available point-of-care sensing devices, to serve as a universal reader for these decentralized diagnostics. We describe a molecular translator that can convert the activation of conventional gene circuit-based sensors into a glucose output that can be read by off-the-shelf glucose meters. We show the development of new glucogenic reporter systems, multiplexed reporter outputs and detection of nucleic acid targets down to the low attomolar range. Using this glucose-meter interface, we demonstrate the detection of a small-molecule analyte; sample-to-result diagnostics for typhoid, paratyphoid A/B; and show the potential for pandemic response with nucleic acid sensors for SARS-CoV-2.

Varicella-zoster virus (VZV) is a neurotropic alphaherpesvirus.Primary VZV infection begins with inoculation of the respiratory mucosa, followed by cell-associated viremia and the rash of chickenpox. During primary infection, the virus establishes latency in sensory ganglia and can subsequently reactivate to cause shingles. At least six VZV open reading frames (ORFs), ORF4, -21, -29, -62, -63, and -66, are expressed during latency (11-13, 29, 38). ORF63 is the most prevalent and abundant VZV transcript expressed in latently infected human ganglia (11,13).VZV ORF63 encodes a 278-amino-acid protein, which is located in the tegument of virions (32) and is expressed as an immediate-early (IE) protein (14). IE63 is extensively modified in infected cells as a 45-kDa protein (14) that is phosphorylated by the VZV ORF47 kinase (30) and cellular casein kinases (5). IE63 binds to IE62, the major transactivator protein of VZV, and up-regulates expression of the VZV glycoprotein I (gI) promoter (36). IE63 has been reported to act as a transcriptional repressor for a number of VZV and heterologous viral and cellular promoters (5, 17). IE63 promotes the survival of cultured primary human neuronal cells (22). Point mutations in phosphorylation sites prior to the last 70 amino acids of IE63 result in mutant viruses impaired for replication (3,8) and for establishment of latent infection in rodents (8). During lytic replication in vitro, IE63 is located predominantly in the nucleus; however, during latency, the protein is detected in the cytoplasm of sensory neurons (18,35,37).The innate immune response is critical for defense against invading viruses. In response to virus infection, a number of signal transduction pathways are activated, including activation of genes that encode type I interferons (IFNs), such as IFN-␣ and IFN-␤. These IFNs inhibit VZV replication in vitro (4, 15). VZV infection of human skin xenografts in SCID mice results in downregulation of IFN-␣ in infected cells and increased expression of IFN-␣ in the surrounding uninfected epidermal cells, which may delay the appearance of skin lesions (33, 34). These findings indicate that IFN-␣ plays an important role in VZV pathogenesis.Previously, we reported the generation of a recombinant VZV in which over 90% of both copies of ORF63 were deleted (7). The ORF63 deletion mutant was impaired for replication in human melanoma cells and for establishment of latency in rodents. Here, we report that the ORF63 deletion mutant is hypersensitive to human IFN-␣ compared to parental virus or other VZV deletion mutants that are impaired for replication in human melanoma cells. IFN-␣ confers cellular resistance against virus infection by at least two cellular proteins, doublestranded RNA-activated protein kinase (PKR) and 2Ј-5Јoligoad-enylate synthetase. Activated PKR phosphorylates the ␣ subunit of eukaryotic initiation factor 2 (eIF-2␣), thereby preventing initiation of translation. We demonstrate that cells infected with the VZV ORF63 deletion mutant have increased levels o...

Leukotoxin (Lkt) secreted by Mannheimia (Pasteurella) haemolytica is an RTX toxin which is specific for ruminant leukocytes. Lkt binds to ␤ 2 integrins on the surface of bovine leukocytes. ␤ 2 integrins have a common ␤ subunit, CD18, that associates with three distinct ␣ chains, CD11a, CD11b, and CD11c, to give rise to three different ␤ 2 integrins, CD11a/CD18 (LFA-1), CD11b/CD18 (Mac-1), and CD11c/CD18 (CR4), respectively. Our earlier studies revealed that Lkt binds to all three ␤ 2 integrins, suggesting that the common ␤ subunit, CD18, may be the receptor for Lkt. In order to unequivocally elucidate the role of bovine CD18 as a receptor for Lkt, a murine cell line nonsusceptible to Lkt (P815) was transfected with cDNA for bovine CD18. One of the transfectants, 2B2, stably expressed bovine CD18 on the cell surface. The 2B2 transfectant was effectively lysed by Lkt in a concentration-dependent manner, whereas the P815 parent cells were not. Immunoprecipitation of cell surface proteins of 2B2 with monoclonal antibodies specific for bovine CD18 or murine CD11a suggested that bovine CD18 was expressed on the cell surface of 2B2 as a heterodimer with murine CD11a. Expression of bovine CD18 and the Lkt-induced cytotoxicity of 2B2 cells were compared with those of bovine polymorphonuclear neutrophils and lymphocytes. There was a strong correlation between cell surface expression of bovine CD18 and percent cytotoxicity induced by Lkt. These results indicate that bovine CD18 is necessary and sufficient to mediate Lkt-induced cytolysis of target cells.Mannheimia (Pasteurella) haemolytica serotype 1 is the major bacterial pathogen of bovine pneumonic pasteurellosis, an acute fibrinous pleuropneumonia, which causes extensive economic losses to the cattle industry in North America and other parts of the world (4). M. haemolytica A1 is commonly found in the tonsillar crypts and the upper respiratory tracts of healthy cattle (9). In conjunction with active viral infection and stress factors, M. haemolytica migrates to the lungs, where it multiplies rapidly (7,26). M. haemolytica produces several virulence factors, of which the extracellular leukotoxin (Lkt) is considered the most important one responsible for leukocyte damage in the lung (3, 27). Lkt-induced neutrophil lysis and degranulation have been implicated as the primary causes of the acute inflammation characteristic of pneumonic pasteurellosis (31).Leukotoxin (Lkt) is a 102-kDa glycoprotein which is produced during the logarithmic phase of bacterial growth in vitro (2, 28). Lkt belongs to the family of RTX (repeats in toxins) toxins and shares extensive homology with the exotoxins produced by other gram-negative bacteria such as Escherichia coli (33), Actinobacillus pleuropneumoniae (8), and Actinobacillus actinomycetemcomitans (17). Despite the extensive homology shared by the RTX family, there is a marked dichotomy among the members of the family with respect to target cell specificity. The toxins secreted by E. coli and A. pleuropneumoniae are lytic to erythrocyte...

Cytomegalovirus (CMV) infection is the most common opportunistic infection in immunosuppressed indiHuman cytomegalovirus (HCMV), also known as human herpesvirus 5 (HHV-5), is a member of the Betaherpesvirus family (including HHV-6 and HHV-7). Cytomegalovirus (CMV) is a double-stranded DNA virus with the largest genome of any herpesvirus. The virus is transmitted horizontally through bodily secretions and can cross the placental barrier to facilitate vertical transmission (reviewed in reference 44). CMV results in a lifelong infection characterized by the establishment of latency in myeloid progenitor cells, followed by periodic reactivation. CMV elicits a strong cellular immune response, and the CMV-specific T cells of some individuals can account for greater than 10% of the total T-cell population (16,22,64). In immunocompetent individuals, CMV infection is generally asymptomatic and controlled by the cell-mediated immune response; however, in immunocompromised individuals (i.e., neonates, transplant patients, and AIDS patients), it can cause severe diseases, such as congenital disorders, CMV retinitis, and a variety of opportunistic infections.Various lab-adapted and clinical strains of HCMV have been isolated and sequenced; most notable are AD169 (13), Toledo (46), Towne (17), and Merlin (15). Furthermore, there are a number of clinical strains that have been cloned as bacterial artificial chromosomes, such as TB40/E (62), TR, PH, and FIX (VR1814) (46). The full-length genomes of CMVs from a number of different animal species, including mice (54), rats (68), guinea pigs (33, 59), and tree shrews (6), have been isolated and sequenced. Given their high degree of genetic relatedness to humans, nonhuman primates (NHPs) likely represent the best animal model to study HCMV biology. A variety of CMVs from Old and New World primates have also been described (37), including chimpanzee CMV (14, 63), rhesus CMV strains 68. 1 and 180.92 (28, 57), cercopithecine herpesvirus 5 (CeHV-5) strains GR2715 and Colburn (accession no. FJ483968 and FJ483969, respectively), squirrel monkey CMV (SsciCMV-1; accession no. FJ483967), and owl monkey CMV (AtriCMV-1; accession no. FJ483970). CMVs are highly species-specific viruses (32, 44) and are consequently incapable of infecting even closely related species (A. P. N. Ambagala et al., unpublished data). This specificity restricts the study of CMV to its target species and reiterates the importance of developing animal models that are closely related to humans in an effort to study HCMV pathogenesis.Animal models to study CMV biology have been largely limited to mice, guinea pigs, and rhesus macaques. As an alternative, cynomolgus macaques (Macaca fascicularis) are a

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The objectives of this study were to identify the mechanism(s) of pseudorabies virus (PrV)-induced down-regulation of porcine class I molecules and the viral protein(s) responsible for the effect. The ability of PrV to interfere with the peptide transport activity of TAP was determined by an in vitro transport assay. In this assay, porcine kidney (PK-15) cells were permeabilized with streptolysin-O and incubated with a library of 125I-labeled peptides having consensus motifs for glycosylation in the endoplasmic reticulum (ER). The efficiency of transport of peptides from the cytosol into the ER was determined by adsorbing the ER-glycosylated peptides onto Con A-coupled Sepharose beads. Dose-dependent inhibition of TAP activity was observed in PrV-infected PK-15 cells. This inhibition, which occurred as early as 2 h postinfection (h.p.i.), reached the maximum level by 6 h.p.i., indicating that TAP inhibition is one of the mechanisms by which PrV down-regulates porcine class I molecules. Infection of cells with PrV in the presence of metabolic inhibitors revealed that cycloheximide a protein synthesis inhibitor, but not phosphonoacetic acid a herpesvirus DNA synthesis inhibitor, could restore the cell surface expression of class I molecules, indicating that late proteins are not responsible for the down-regulation. Infection in the presence of cycloheximide followed by actinomycin-D, which results in accumulation of the immediate-early protein, failed to down-regulate class I, indicating that one or more early proteins are responsible for the down-regulation of class I molecules.