Infection by bovine alphaherpesvirus types 1 and 5 induces IFN-λ3 expression in neuronal-type cells and bovine neural tissues.

Type III interferons (IFNs) are components of the innate immunity, with IFN lambda- (λ)3 having the most potent bioactivity in humans. IFN-λ has a predominant role in epithelial cells. However, antiviral function in certain infections of the central nervous system has also been demonstrated. IFN-λ3 expression in neural tissues of cattle has not been investigated. Thus, the aim of this study was to analyze whether an antiviral IFN-λ3 response is mounted after infection with bovine alphaherpesviruses (BoHV-1 and BoHV-5) in vitro, in neuronal-type cells, and in neural tissues from experimentally-infected calves. This study demonstrated that there is a strong IFN-λ3 response early after BoHV-1infection of undifferentiated neuroblastoma cells. During acute BoHV-1 and BoHV-5 infection of calves, low levels of IFN-λ3 expression were detected in the brain, which would favor virus spread within this tissue. Striking differences in the transcriptional levels of IFN-λ3 were observed in trigeminal ganglion, particularly in BoHV-1-acutely- and latently-infected calves. During reactivation, IFN-λ3 expression was down-regulated, which may be a requirement for virus replication and spread. Overall, different patterns of IFN-λ3 expression were detected during BoHV-1 and BoHV-5 infection, particularly during latency.

Regional binding of tau and amyloid PET tracers in Down syndrome autopsy brain tissue.

INTRODUCTION: Tau pathology is a major age-related event in Down syndrome with Alzheimer's disease (DS-AD). Although recently, several different Tau PET tracers have been developed as biomarkers for AD, these tracers showed different binding properties in Alzheimer disease and other non-AD tauopathies. They have not been yet investigated in tissue obtained postmortem for DS-AD cases. Here, we evaluated the binding characteristics of two Tau PET tracers (3H-MK6240 and 3H-THK5117) and one amyloid (3H-PIB) ligand in the medial frontal gyrus (MFG) and hippocampus (HIPP) in tissue from adults with DS-AD and DS cases with mild cognitive impairment (MCI) compared to sporadic AD. METHODS: Tau and amyloid autoradiography were performed on paraffin-embedded sections. To confirm respective ligand targets, adjacent sections were immunoreacted for phospho-Tau (AT8) and stained for amyloid staining using Amylo-Glo. RESULTS: The two Tau tracers showed a significant correlation with each other and with AT8, suggesting that both tracers were binding to Tau deposits. 3H-MK6240 Tau binding correlated with AT8 immunostaining but to a lesser degree than the 3H-THK5117 tracer, suggesting differences in binding sites between the two Tau tracers. 3H-THK5117, 3H-MK6240 and 3H-PIB displayed dense laminar binding in the HIPP and MFG in adult DS brains. A regional difference in Tau binding between adult DS and AD was observed suggesting differential regional Tau deposition in adult DS compared to AD, with higher THK binding density in the MFG in adult with DS compared to AD. No significant correlation was found between 3H-PIB and Amylo-Glo staining in adult DS brains suggesting that the amyloid PIB tracer binds to additional sites. CONCLUSIONS: This study provides new insights into the regional binding distribution of a first-generation and a second-generation Tau tracer in limbic and neocortical regions in adults with DS, as well as regional differences in Tau binding in adult with DS vs. those with AD. These findings provide new information about the binding properties of two Tau radiotracers for the detection of Tau pathology in adults with DS in vivo and provide valuable data regarding Tau vs. amyloid binding in adult DS compared to AD.

Cathelicidin bovine myeloid antimicrobial peptide (BMAP) 28 is involved in the inflammatory response against alpha-herpesviruses in the bovine nervous system.

The role of the local innate immune response in the neuropathogenesis of bovine herpesvirus (BoHV) type 1 and 5 remains largely unknown. This study determined the gene transcriptional expression of relevant bovine cathelicidins, TNFα and IFNß in the nervous system of experimentally-infected cattle during the different stages of BoHV-1 and BoHV-5 infectious cycle. We studied the modulation of bovine myeloid antimicrobial peptide (BMAP) 27 and 28 by alpha-herpesviruses during acute infection of the central nervous system (CNS). However, BMAP28 was the main cathelicidin modulated. BoHV-5 supressed BMAP28 expression mainly in frontal cortex and cervical medulla whereas BoHV-1 slightly induced the expression of cathelicidins in the olfactory and posterior cortex. The differences in the regulation of the innate response are likely related to distinct replication rates of both alpha-herpesviruses in the CNS. During latency and reactivation, BoHV-1 and -5 decreased BMAP28 and BMAP27 expression, accompanied by high levels of TNFα and IFNß transcripts in the posterior brain region and medulla during BoHV reactivation. In terms of cytokines, a remarkably overexpression of IFNß was induced by BoHV-5 (133.8-fold). In trigeminal ganglion (TG) both alpha-herpesviruses induced cathelidicins gene expression at all stages of the infection cycle, while only acute BoHV-5 infection increased TNFα (129-fold) mRNA levels. This study suggests that the pronounced downregulation of BMAP28 in BoHV-5-acutely-infected CNS is due to a decreased immune stimulation during viral infection, favouring its establishment in the CNS with a low replication rate until latency. Thus, cathelicidins, together with IFNß and TNFα, are differentially regulated by BoHV-5 and BoHV-1 infections and this regulation is dependent on the stage of virus infection in the bovine nervous system.

Modulation of cathelicidins, IFNß and TNFα by bovine alpha-herpesviruses is dependent on the stage of the infectious cycle.

Production of antimicrobial peptides cathelicidins, interferons and cytokines is an important feature in airway epithelial host defense. The innate immune response to alpha-herpesvirus infection at the sites of primary replication has not been fully studied. Thus, the aim of this study was to determine the expression of innate immune components, cathelicidins, IFNß, TNFα and TNF receptors (TNFRI and TNFRII) during acute infection and reactivation of bovine herpesvirus type 1 (BoHV-1) and 5 (BoHV-5) in the respiratory tract and lymphoid tissue of their natural host. We found that BoHV infection modulates mainly the expression of BMAP28, a key cathelicidin in cattle. It was downregulated by both viruses in retropharyngeal lymph nodes of acutely infected-calves, and it was accompanied by a lower expression of IFNß, TNFα and TNFRI. BoHV-5 showed a pronounced role in the downregulation of BMAP28, even in nasal mucosa and lung. However, during reactivation, BoHV-5 upregulated both BMAP28 and IFNß in retropharyngeal lymph nodes. Acute replication induced also TNFα mRNA and protein synthesis, and expression of TNFRI and II was positively regulated during both acute infection and reactivation, particularly in the trachea. Moreover, BMAP27 was detected during BoHV-1 reactivation suggesting a potential role at this stage. Thus, cathelicidins are implicated in alpha-herpesvirus infections of the bovine respiratory system and the response is distinct during BoHV-1 and BoHV-5 acute infection and reactivation. This demonstrates that these viruses modulate differentially the components of innate immune response, possibly influencing their pathogenesis. This study provides an initial pilot analysis of factors that might be implicated in alpha-herpesvirus infection of the bovine respiratory system.

HDAC2 dysregulation in the nucleus basalis of Meynert during the progression of Alzheimer's disease.

AIMS: Alzheimer's disease (AD) is characterized by degeneration of cholinergic basal forebrain (CBF) neurons in the nucleus basalis of Meynert (nbM), which provides the major cholinergic input to the cortical mantle and is related to cognitive decline in patients with AD. Cortical histone deacetylase (HDAC) dysregulation has been associated with neuronal degeneration during AD progression. However, whether HDAC alterations play a role in CBF degeneration during AD onset is unknown. We investigated global HDAC protein levels and nuclear HDAC2 immunoreactivity in tissue containing the nbM, changes and their association with neurofibrillary tangles (NFTs) during the progression of AD. METHODS: We used semi-quantitative western blotting and immunohistochemistry to evaluate HDAC and sirtuin (SIRT) levels in individuals that died with a premortem clinical diagnosis of no cognitive impairment (NCI), mild cognitive impairment (MCI), mild/moderate AD (mAD) or severe AD (sAD). Quantitative immunohistochemistry was used to identify HDAC2 protein levels in individual cholinergic nbM nuclei and their colocalization with the early phosphorylated tau marker AT8, the late-stage apoptotic tau marker TauC3 and Thioflavin-S, a marker of ß-pleated sheet structures in NFTs. RESULTS: In AD patients, HDAC2 protein levels were dysregulated in the basal forebrain region containing cholinergic neurons of the nbM. HDAC2 nuclear immunoreactivity was reduced in individual cholinergic nbM neurons across disease stages. HDAC2 nuclear reactivity correlated with multiple cognitive domains and with NFT formation. CONCLUSIONS: These findings suggest that HDAC2 dysregulation contributes to cholinergic nbM neuronal dysfunction, NFT pathology, and cognitive decline during clinical progression of AD.

Effect of magnetic ion exchange (MIEX®) on removal of emerging organic contaminants.

In this study, the removal of nine emerging organic contaminants was investigated by using anion exchange resins. The selected compounds were carbamazepine, atrazine, simazine, estrone, bisphenol A, methylparaben, ethylparaben, propylparaben and butylparaben. Two different magnetic anionic exchanger resins were tested: MIEX® DOC and MIEX® GOLD. The optimal resin dose (40 mL/L) and contact time (20 min) had been previously determined. Once these optimum parameters were set, the effect of the initial concentration of contaminants on the removal efficiency of the contaminants by the resins was studied. The study was carried out using mono and multicomponent systems, with distilled water and natural waters, to which contaminants had been previously added, in order to evaluate the competitive and matrix effects. Results showed that the average removal percentages obtained with the MIEX® DOC resin were: 51%, 61%, 68% and 80% for methyl-, ethyl-, propyl-, and butylparaben, respectively. For bisphenol A the result was similar, i.e., 66%, whereas for the rest of the compounds studied, removal efficiencies lower than 15% were obtained. The MIEX® GOLD resin achieved lower elimination rates than the MIEX® DOC resin in all cases.

Immunization with inactivated antigens of Neospora caninum induces toll-like receptors 3, 7, 8 and 9 in maternal-fetal interface of infected pregnant heifers.

Neospora caninum is an obligate parasite and a major cause of abortion in cattle. Pregnancy failures appear to be associated with weak innate defences on the maternal-fetal interface during infection with N. caninum. Herein, we studied the gene expression of Toll-like receptors (TLRs) in pregnant heifers immunized with different vaccine formulations against N. caninum before mating and then challenged the heifers with live N. caninum on day 70 of gestation. TLR7 and TLR8 expression was upregulated in the placental caruncle of infected-pregnant heifers previously exposed to live N. caninum as immunogen. However, TLR7 and 8 expression in both placenta and caruncle as well as, TLR3 and 9 expression in caruncle were upregulated when heifers were previously immunized with inactivated soluble whole antigens and recombinant NcSAG1, NcHSP20 and NcGRA7 proteins. All dams were carrying viable fetuses when they were culled at day 104 of gestation. Upregulation of TLR7 and IFNγ expression was detected in fetal spleen when their mothers where previously vaccinated with soluble antigens and recombinant NcSAG1, NcHSP20 and NcGRA7 proteins. These studies demonstrate that soluble or recombinant NcSAG1, NcHSP20 and NcGRA7 antigens induce key TLRs expression at the maternal-fetal interface, probably triggering damaging inflammatory cellular immune responses associated with abortion. Previous infection with N. caninum seems to attenuate the innate immune response at the maternal-fetal interface, which could favour pregnancy maintenance and perpetuation of the disease. This finding represents novel information on how N. caninum vaccination and infection modulate TLRs expression at the placenta and fetal spleen, the possible role in the pregnancy outcomes and transplacental transmission of the protozoa.

Toll-like receptors 3, 7 and 8 are upregulated in the placental caruncle and fetal spleen of Neospora caninum experimentally infected cattle.

Innate immune responses at the maternal-fetal interface are key in the pathogenesis of Neospora caninum, an obligate parasite that causes abortion in cattle. Herein, we determined the gene expression of endosomal Toll-like receptors (TLRs) in the placenta and fetuses from both non-infected pregnant heifers and pregnant heifers intravenously challenged with live tachyzoites of N. caninum on day 70 of gestation. On day 104 of pregnancy, mRNA expression of TLRs 3 and 8, as well as that of TLRs 7 and 9, was high in the spleen of fetuses from N. caninum-infected heifers. Gene expression levels of endosomal TLRs were also detectable in the placenta and the maternal caruncle from infected heifers, being TLRs 3, 7 and 8 particularly upregulated, mostly in the caruncle. Basal TLR levels were higher in fetal spleen than in placental tissues. This study provides novel information on how innate TLR responses are induced at the maternal-fetal interface of cattle in response to intracellular N. caninum.

Training-related improvements in musculoskeletal health and balance: a 13-week pilot study of female cancer survivors.

Cancer survivors often experience poor post-treatment musculoskeletal health. This study examined the feasibility of combined aerobic and resistant training (CART) for improving strength, skeletal health and balance. Cancer survivors (n = 24) were identified by convenience sampling in Los Angeles County with 11 survivors consenting to 13 weeks of CART. Pre- and post-intervention assessments of bone mineral density (BMD), strength, flexibility and biomarker analysis were performed. Paired t-test analysis suggested increases in lower and upper body strength. The average T-score for BMD at the femoral neck improved from -1.46 to -1.36 and whole body BMD improved from -1.65 to -1.55. From baseline to follow-up, participants also displayed decreases in sway velocity on the eyes open (7%) and eyes closed (27%) conditions. Improvement in lower body strength was associated with increases in lean body mass (LBM) (r = 0.721) and an inverse association was observed between sway velocity and LBM (r = 0.838). Age and time since last treatment were related with biomarkers of anabolic growth (IGF-1, IGFbp-3) and bone (DPD, BAP). In summary, observed physiological changes were consistent with functional improvements, suggesting that isometric and dynamic exercise prescription may reduce the risk for falls and fall-related fractures among survivors.

EWS-FLI1-mediated suppression of the RAS-antagonist Sprouty 1 (SPRY1) confers aggressiveness to Ewing sarcoma.

Ewing sarcoma is characterized by chromosomal translocations fusing the EWS gene with various members of the ETS family of transcription factors, most commonly FLI1. EWS-FLI1 is an aberrant transcription factor driving Ewing sarcoma tumorigenesis by either transcriptionally inducing or repressing specific target genes. Herein, we showed that Sprouty 1 (SPRY1), which is a physiological negative feedback inhibitor downstream of fibroblast growth factor (FGF) receptors (FGFRs) and other RAS-activating receptors, is an EWS-FLI1 repressed gene. EWS-FLI1 knockdown specifically increased the expression of SPRY1, while other Sprouty family members remained unaffected. Analysis of SPRY1 expression in a panel of Ewing sarcoma cells showed that SPRY1 was not expressed in Ewing sarcoma cell lines, suggesting that it could act as a tumor suppressor gene in these cells. In agreement, induction of SPRY1 in three different Ewing sarcoma cell lines functionally impaired proliferation, clonogenic growth and migration. In addition, SPRY1 expression inhibited extracellular signal-related kinase/mitogen-activated protein kinase (MAPK) signaling induced by serum and basic FGF (bFGF). Moreover, treatment of Ewing sarcoma cells with the potent FGFR inhibitor PD-173074 reduced bFGF-induced proliferation, colony formation and in vivo tumor growth in a dose-dependent manner, thus mimicking SPRY1 activity in Ewing sarcoma cells. Although the expression of SPRY1 was low when compared with other tumors, SPRY1 was variably expressed in primary Ewing sarcoma tumors and higher expression levels were significantly associated with improved outcome in a large patient cohort. Taken together, our data indicate that EWS-FLI1-mediated repression of SPRY1 leads to unrestrained bFGF-induced cell proliferation, suggesting that targeting the FGFR/MAPK pathway can constitute a promising therapeutic approach for this devastating disease.

Distribution of bovine alpha-herpesviruses and expression of toll-like receptors in the respiratory system of experimentally infected calves.

This study provides an initial analysis of the toll-like receptors (TLRs) that might be implicated in alpha-herpesvirus infection of the bovine respiratory system. A significant variation in the expression of TLR3 and TLRs 7-9 during bovine herpesvirus type 1 (BoHV-1) and 5 (BoHV-5) acute infections and particularly an up-regulation during viral reactivation in respiratory tissues has been demonstrated. Furthermore, viral distribution in the respiratory tract of BoHV-1- and BoHV-5-infected calves at different stages of the infectious cycle was analysed. The wide distribution of BoHV DNA in the respiratory tract during acute infection was restricted during latent infection and the subsequent reactivation of BoHV-1 and BoHV-5. Overall, the findings presented here contribute to the knowledge on the replication and dissemination of bovine alpha-herpesviruses. Furthermore, some of the immune factors triggered in the host that determine the different outcomes of infection by two closely related pathogens of cattle have been elucidated.

Comparative study on the in vitro replication and genomic variability of Argentinean field isolates of bovine herpesvirus type 4 (BoHV-4).

Bovine herpesvirus 4 (BoHV-4) is a gammaherpesvirus, belonging to the Rhadinovirus genus, which is increasingly associated with various problems of the reproductive tract of cattle. In Argentina, analysis of BoHV-4 strains isolated from cervico-vaginal mucus of aborted cows revealed a high genetic divergence among strains, which could be classified in three different groups: Genotype 1 comprises Movar-like strains (European prototype), Genotype 2 includes DN599-like strains (American prototype) and Genotype 3 corresponds to a novel genotype group. Understanding the replication behavior in cell cultures and the molecular characteristics of this pathogen of cattle is critical for the rational design of in vitro experiments. The aim of this work was to quantitatively evaluate the replication properties of different Argentinean BoHV-4 strains and to characterize their phylogenetic relationships. Significant differences were evident among the virus titers of the different BoHV-4 isolates in vitro. The most conserved gene was the major capsid protein (ORF25). The glycoprotein B (gB), glycoprotein H (gH), and thymidine kinsase (TK) genes displayed both synonymous and non-synonymous substitutions, with the highest diversity observed for gB, which displayed amino acid substitutions in 24 out of the 178 positions examined. Strains 09/759, 12/512, and 07/568 presented a deletion encompassing amino acid position 27 to 35, whereas strains 07/435 and 09/227 had a deletion from position 28 to 35. Two strains, 07/435 and 09/227, also displayed the highest divergence compared to the other strains analyzed. This study provides information about the in vitro replication and behavior of nine field isolates of BoHV-4. These findings are relevant since available information on the in vitro growth characteristics of BoHV-4 strains is scarce. The results from this study may also be useful for establishing comparisons with other related viruses.

Distribution of bovine herpesvirus type 1 in the nervous system of experimentally infected calves.

Bovine herpesvirus type 1 (BoHV-1) is responsible for respiratory and genital disease in cattle. BoHV-1 encephalitis is only occasionally reported. However, several cases of neurological disease have been recently attributed to BoHV-1. In this study, the distribution and pathological alterations caused by two BoHV-1 strains in the nervous system of experimentally infected calves during acute infection and reactivation are described. Calves were inoculated intranasally with BoHV-1 Los Angeles (BoHV-1.LA) or Cooper (BoHV-1.Cooper) strains. Acutely infected calves were euthanased at 6 days (BoHV-1.Cooper, n = 2) and 7 days post-inoculation (BoHV-1.LA, n = 2). Latently infected calves that were given dexamethasone to induce reactivation were euthanased at 2 days (BoHV-1.Cooper, n = 2) or 5 days (BoHV-1.LA, n = 2) after dexamethasone administration. Both BoHV-1 strains were isolated from the brains of acutely infected calves. Distribution of viral DNA in the neural tissues was similar for both strains. During reactivation, neither BoHV-1.LA nor BoHV-1.Cooper was isolated from any brain section or trigeminal ganglia in infected calves. Macroscopic lesions were not evident in any group. In BoHV-1.LA infected calves, microscopic lesions were found in the brain but not in the trigeminal ganglia. Microscopic lesions in the brain of BoHV-1.Cooper infected calves were not as evident as in BoHV-1.LA infected animals. However, mononuclear infiltrates and neuronophagia were present in trigeminal ganglia. The results of this study demonstrated that respiratory BoHV-1 strains are able to replicate and disseminate within the bovine nervous tissue and provide evidence of the neuroinvasiveness of BoHV-1 strains.

Hippocampal plasticity during the progression of Alzheimer's disease.

Neuroplasticity involves molecular and structural changes in central nervous system (CNS) throughout life. The concept of neural organization allows for remodeling as a compensatory mechanism to the early pathobiology of Alzheimer's disease (AD) in an attempt to maintain brain function and cognition during the onset of dementia. The hippocampus, a crucial component of the medial temporal lobe memory circuit, is affected early in AD and displays synaptic and intraneuronal molecular remodeling against a pathological background of extracellular amyloid-beta (Aß) deposition and intracellular neurofibrillary tangle (NFT) formation in the early stages of AD. Here we discuss human clinical pathological findings supporting the concept that the hippocampus is capable of neural plasticity during mild cognitive impairment (MCI), a prodromal stage of AD and early stage AD.

Resistance training suppresses intra-abdominal fatty acid synthesis in ovariectomized rats.

Ovarian hormone loss is associated with a shift in fat distribution to intra-abdomin al adipose tissue (intra-AAT) depots and with lipid metabolism disorders, which predisposes individuals to developing insulin resistance. Resistance training (RT) prevents increases in intra-AAT after ovarian hormone loss. However, the molecular mechanisms underlying these changes remain unclear. We investigated the effects of ovariectomy and RT on gene expression related to lipogenesis and fat oxidation in the intra-AAT of ovariectomized rats. Sprague-Dawley rats (n=6/group) were divided into the groups: sham-sedentary, ovariectomized-sedentary, sham-RT and ovariectomized-RT. RT groups performed a 10-week climbing program on a ladder with progressive overload. Intra-AAT was subjected to morphometric and mRNA analysis. Ovariectomized-sedentary group had larger adipocytes and higher expression of peroxisome proliferator-activated receptor-γ (PPAR-γ), sterol regulatory element-binding protein-1c (SREBP-1c), stearoyl-CoA desaturase-1 (SCD-1), acetyl-CoA carboxylase (ACC), hormone-sensitive lipase (HSL) and lower expression of the oxidative carnitinepalmitoyltransferase-I (CPT-1). RT counteracted OVX-induced increases in PPAR-γ and SCD-1 and decreased SREBP-1c. ACC and HSL were downregulated in ovariectomized-RT compared with the ovariectomized-sedentary group. Ovariectomized-RT group had the highest CPT-1 gene expression. Adipocyte size decreased in ovariectomized-RT group. Results suggest that RT reduces intra-AAT adipocyte size in ovariectomized rats by suppressing intra-AAT fatty acid synthesis and enhancing fatty acid ß-oxidation.

Toll-like receptor expression in the nervous system of bovine alpha-herpesvirus-infected calves.

In this study, the expression levels of viral Toll-like receptors (TLRs) in the nervous system of bovine herpesvirus type 5 (BoHV-5)-infected calves were investigated. A significant increase in the expression of TLRs 3 and 7-9 was found in the anterior cerebral cortex during acute infection and viral reactivation. In the trigeminal ganglia, only TLR9 expression was significantly affected. The magnitude of the increase was lower in BoHV-1-infected calves, suggesting that a restricted immune response might protect against exacerbated inflammatory responses in the brain. This work describes, for the first time, the involvement of TLRs 3 and 7-9 in the recognition of BoHV in the bovine nervous system, indicating that the expression of these receptors might be associated with the development of neurological disease. Modulation of the signalling pathways mediated by TLRs might provide an effective approach to control the neuro-immune response to BoHV-5, which may be responsible for neurological lesions.

Increased lactate threshold after five weeks of treadmill aerobic training in rats.

The aim of the present study was to analyse the lactate threshold (LT) changes in rats submitted to an aerobic treadmill-training programme. Twenty-five Wistar rats were divided into two groups: a sedentary control group (CG), and a trained group (TG) submitted to an aerobic training during 5 weeks. All the animals were submitted to an incremental treadmill exercise test in order to determine LT. There was an increase in the maximum running speed in the TG (from 32.25 ± 1.27 to 47.75 ± 3.13 m.min-1 - p = 0.001), and running speed at LT (from 26.21 ± 1.15 to 35.30 ± 2.24 m.min-1 - p = 0.004), a part from the reduction in blood lactate at LT. LT can be determined in rats, and aerobic training induced positive oxidative physiological adaptations in the animals.

Latency of bovine herpesvirus type 5 (BoHV-5) in tonsils and peripheral blood leukocytes.

Bovine herpesvirus types 1 (BoHV-1) and 5 (BoHV-5) can both establish latency in the trigeminal ganglion. Non-neural sites of latency have been described for BoHV-1 but not for BoHV-5. The aim of this study was to determine whether peripheral blood leukocytes and tonsils are targets for BoHV-5 infection and to establish whether all stages of that virus's infectious cycle can occur in those cell types. Comparisons with BoHV-1 infection of these tissues were also made in order to better understand the pathogenesis of both viruses. BoHV-1 and BoHV-5 were isolated from tonsils of acutely-infected calves. BoHV-5 was also isolated from a tonsil homogenate after dexamethasone-induced reactivation. During latency, infectious virus was recovered from a tonsil explant of one BoHV-5-infected calf. The genomes of BoHV-5 and BoHV-1 were detected in tonsils from acutely-infected calves although were not detected in tonsils from latently-infected calves or from calves treated with dexamethasone. Virus DNA was intermittently detected in leukocytes. The study has shown that BoHV-5 can establish latency in bovine tonsils and peripheral white blood cells, and that it can be reactivated from latently-infected tonsils, which might contribute to viral transmission. The titres of BoHV-1 and BoHV-5 in tonsils were similar, suggesting that replication at this site is a common feature for both viruses.

Toll-like receptor activation and expression in bovine alpha-herpesvirus infections.

The involvement of Toll-like receptors (TLRs) in bovine herpesvirus types 1 (BoHV-1) and 5 (BoHV-5) infections has not been analyzed. In this study, the role of TLR signaling on virus replication was investigated. Blood leukocytes consistently express TLRs. Thus, our approach was to study in vitro the effects of agonist stimulation of TLRs expressed by peripheral blood leukocytes on BoHV-1 and BoHV-5 replication. Furthermore, the patterns of TLRs 3, 7-9 expression on virus-infected-bovine leukocytes were analyzed. Only Imiquimod (TLR7/8 agonist) showed anti-viral activity on infected MDBK cells. This is the first evidence that the timely activation of TLR7/8 signaling is effective in impairing BoHV-1 and 5 replication, thereby providing an experimental indication that Imiquimod may be a promising immune modulator. This work describes, for the first time, the expression patterns of TLRs in BoHV-1- or BoHV-5-infected-bovine leukocytes, suggesting the involvement of TLR7 and TLR9 in the recognition of these viruses.