Svetlana F. Khaiboullina

Hantaviruses: Molecular Biology, Evolution and Pathogenesis

Hantaviruses are tri-segmented negative sense single stranded RNA viruses that belong to the family Bunyaviridae. In nature, hantaviruses are exclusively maintained in the populations of their specific rodent hosts. In their natural host species, hantaviruses usually develop a persistent infection with prolonged virus shedding in excreta. Humans become infected by inhaling virus contaminated aerosol. Unlike asymptomatic infection in rodents, hantaviruses cause two acute febrile diseases in humans: hemorrhagic fever with renal syndrome (HFRS) and hantavirus pulmonary syndrome (HPS). The mortality rate varies from 0.1% to 40% depending on the virus involved. Hantaviruses are distributed world wide, with over 150,000 HFRS and HPS cases being registered annually. In this review we summarize current knowledge on hantavirus molecular biology, epidemiology, genetic diversity and co-evolution with rodent hosts. In addition, special attention was given in this review to describing clinical manifestation of HFRS and HPS, and advances in our current understanding of the host immune response, treatment, and prevention.

Characterization of an Antisense Transcript Spanning the UL81-82 Locus of Human Cytomegalovirus

ABSTRACT In this study we present the characterization of a novel transcript, UL81-82ast, UL81-82 antisense transcript, and its protein product. The transcript was initially found in a cDNA library of monocytes from a seropositive donor. mRNA was obtained from monocytes isolated from a healthy donor with a high antibody titer against human cytomegalovirus (HCMV). The mRNAs were cloned into a lambda phage-derived vector to create the cDNA library. Using PCR, UL81-82ast was amplified from the library. The library was tested for the presence of numerous HCMV genes. Neither structural genes nor immediate-early genes were found. UL81-82ast was detected in five bone marrow samples from healthy antibody-positive donors. This same transcript was also found in in vitro-infected human fibroblasts early after infection but disappears at the same time that UL82 transcription begins. Not only was the transcript amplified using reverse transcription-PCR and sequenced but its protein product (UL82as protein) was detected by both Western blot and immunofluorescence. Phylogenetic studies using UL82as protein were conducted, showing a high degree of conservation in clinical isolates, laboratory strains of HCMV, and even in chimpanzee CMV. The transcript could be involved in the posttranscriptional regulation of the UL82 gene, affecting its mRNA stability or translation. Since the UL82 product, pp71, functions as an immediate-early transactivator, its posttranscriptional control could have some effect over latency reactivation and lytic replication.

Influence of omega-3 fatty acids on the growth of human colon carcinoma in nude mice

The present study investigated the influence of dietary omega-3 fatty acid supplementation on the growth of human colon carcinoma xenograft in athymic nude mice. Four diets were fed to evaluate the effect of levels and types of fat on colon tumor growth. Animals were maintained on a standard diet modified by addition of fats containing omega-3 and omega-6 fatty acids to represent high and low fat intakes for 53 days. The final mean estimated tumor weight for the high fat corn oil (24%) fed group was 2,302 mg, whereas the low fat (8% corn oil) group was 1,681 mg. The final mean tumor weight of the high fat menhaden oil fed group was 782 mg representing a 66% decrease in growth compared to the high fat corn oil group and a decrease of 54% compared to the low corn oil fed group. The high fat golden algae oil fed group resulted in a mean final tumor weight of 223 mg representing a 90% inhibition of tumor growth relative to the high fat corn oil fed group and 87% inhibition of growth compared to the low fat corn oil fed group. These findings indicate that dietary omega-3 fatty acids possess significant tumor suppressing properties and that the primary tumor suppressing fatty acid is docosahexaenoic acid. Histopathologic examination of control and treated tumors and expression array analyses (human cytokine and apoptosis arrays) support the tumor growth inhibition data and provide evidence for discussion of possible mechanisms for the observed growth inhibition.

Effects of Tumor Necrosis Factor Alpha on Sin Nombre Virus Infection In Vitro

ABSTRACT Previous data indicate that immune mechanisms may be involved in developing capillary leakage during Sin Nombre virus (SNV) infection. Therefore, we investigated production of tumor necrosis factor alpha (TNF-α) by human alveolar macrophages and human umbilical vein endothelial cells (HUVEC) after infection with SNV. In addition, we examined the effect of TNF-α on HUVEC monolayer leakage. Our results reveal that although TNF-α decreases accumulation of viral nucleoproteins, TNF-α levels do not change in SNV-infected cells. In addition, supernatants from SNV-infected human alveolar macrophages did not cause a significant increase in endothelial monolayer permeability.

Human cytomegalovirus persists in myeloid progenitors and is passed to the myeloid progeny in a latent form

CD34+ progenitor cells can harbour latent human cytomegalovirus (HCMV); however, the mechanisms of HCMV latency remain unclear. We have investigated the effects of the haematopoietic lineage restriction on the establishment and spread of the latent HCMV to progeny cells. In vitro‐infected and latently‐infected haematopoietic progenitor cells derived from HCMV seropositive donors were studied. The presence of HCMV DNA in bone marrow progenitor (BMP) cells was determined by single colony polymerase chain reaction and fluorescent in situ hybridization (FISH). The presence of CMV DNA was found to be restricted to myeloid progenitors and the percentage of HCMV‐infected cells was lower in naturally‐infected cells than in in vitro‐infected cells. Erythroid differentiation resulted in an abortive infection with persistence of the viral nucleic acids in red cell precursors. In BMP cells from HCMV seronegative donors, HCMV DNA was localized in the nucleus. Bone marrow progenitors in the presence of granulocyte‐macrophage colony stimulating factor (GMCSF) maintained HCMV DNA for extended periods of time. No viral production could be detected throughout the culture but the comparison of the numbers of latently‐infected cells prior to and after the culture suggests that proliferation of haematopoietic progenitor cells may lead to the expansion of latently‐infected cells.

Regulation of Cellular Gene Expression in Endothelial Cells by Sin Nombre and Prospect Hill Viruses

Mechanisms of hantavirus-induced vascular leakage remain unknown. This study was initiated to determine whether hantavirus-induced changes in endothelial cell gene expression may provide insight into disease mechanisms. Additionally, by using pathogenic Sin Nombre virus (SNV) and non-pathogenic Prospect Hill virus (PHV), we wanted to identify cellular responses that are likely to differentiate pathogenic from nonpathogenic hantaviruses. Using the Affymetrix DNA Array, we found that PHV and SNV did not significantly differ in the number of activated genes (18 versus 14 genes) in infected endothelial cells at 4 h PI. However, a smaller group of genes (36) were up-regulated by PHV compared to SNV (175) at 12 h PI. Only two genes were down-regulated in SNV-infected cells. Expression of the functionally diverse group of genes was altered at an early stage of infection (4 and 12 h PI). The genes affected include putative anti-viral factors, transcription factors, growth factors, chemokines, receptors, structural proteins, metabolism, and kinases. Although many genes were activated in cells infected with SNV and PHV, overall cellular transcriptional responses were more altered by pathogenic SNV compared to non-pathogenic PHV.

Cytokine expression provides clues to the pathophysiology of Gulf War illness and myalgic encephalomyelitis

Gulf War illness (GWI) is a chronic disease of unknown etiology characterized by persistent symptoms such as cognitive impairment, unexplained fatigue, pervasive pain, headaches, and gastrointestinal abnormalities. Current reports suggest that as many as 200,000 veterans who served in the 1990-1991 Persian Gulf War were afflicted. Several potential triggers of GWI have been proposed including chemical exposure, toxins, vaccines, and unknown infectious agents. However, a definitive cause of GWI has not been identified and a specific biological marker that can consistently delineate the disease has not been defined. Myalgic encephalomyelitis (ME) is a disease with similar and overlapping symptomology, and subjects diagnosed with GWI typically fit the diagnostic criteria for ME. For these reasons, GWI is often considered a subgroup of ME. To explore this possibility and identify immune parameters that may help to understand GWI pathophysiology, we measured 77 serum cytokines in subjects with GWI and compared these data to that of subjects with ME as well as healthy controls. Our analysis identified a group of cytokines that identified ME and GWI cases with sensitivities of 92.5% and 64.9%, respectively. The five most significant cytokines in decreasing order of importance were IL-7, IL-4, TNF-α, IL-13, and IL-17F. When delineating GWI and ME cases from healthy controls, the observed specificity was only 33.3%, suggesting that with respect to cytokine expression, GWI cases resemble control subjects to a greater extent than ME cases across a number of parameters. These results imply that serum cytokines are representative of ME pathology to a greater extent than GWI and further suggest that the two diseases have distinct immune profiles despite their overlapping symptomology.

Plasmacytoid dendritic cells of the gut: relevance to immunity and pathology.

Plasmacytoid dendritic cells (pDCs) are bone marrow-derived immune cells with the ability to express copious amounts of type I and III interferon (IFN) and can differentiate into antigen-presenting dendritic cells as a result of stimulation by pathogen-derived nucleic acid. These powerful combined functionalities allow pDCs to bridge the innate and adaptive immune systems resulting in a concerted pathogen response. The contribution of pDCs to gastrointestinal immunity is only now being elucidated and is proving to be a critical component in systemic immunity. This review will explore the immunology of pDCs and will discuss their involvement in human disease and tolerance with an emphasis on those in the gastrointestinal lymphoid tissue.

Elevated Levels of Proinflammatory Cytokines in Cerebrospinal Fluid of Multiple Sclerosis Patients

Multiple sclerosis (MS) is an autoimmune neurodegenerative disease characterized by chronic brain inflammation. Leukocyte infiltration of brain tissue causes inflammation, demyelination, and the subsequent formation of sclerotic plaques, which are a hallmark of MS. Activation of proinflammatory cytokines is essential for regulation of lymphocyte migration across the blood–brain barrier. We demonstrate increased levels of many cytokines, including IL-2RA, CCL5, CCL11, MIF, CXCL1, CXCL10, IFNγ, SCF, and TRAIL, were upregulated in cerebrospinal fluid (CSF), whereas IL-17, CCL2, CCL3, CCL4, and IL-12(p40) were activated in MS serum. Interaction analysis of cytokines in CSF demonstrated a connection between IFNγ and CCL5 as well as MIF. Many cells can contribute to production of these cytokines including CD8 and Th1 lymphocytes and astrocytes. Therefore, we suggest that IFNγ released by Th1 lymphocytes can activate astrocytes, which then produce chemoattractants, including CCL5 and MIF. These chemokines promote an inflammatory milieu and interact with multiple chemokines including CCL27 and CXCL1. Of special note, upregulation of CCL27 was found in CSF of MS cases. This observation is the first to demonstrate CCL27 as a potential contributor of brain pathology in MS. Our data suggest that CCL27 may be involved in activation and migration of autoreactive encephalitogenic immune effectors in the brain. Further, our data support the role of Th1 lymphocytes in the pathogenesis of brain inflammation in MS, with several cytokines playing a central role.

Plasmacytoid dendritic cells, a role in neoplastic prevention and progression.

Plasmacytoid dendritic cells (pDCs) are multifunctional bone‐marrow‐derived immune cells that are key players in bridging the innate and adaptive immune systems. Activation of pDCs through toll‐like receptor agonists has proven to be an effective treatment for some neoplastic disorders.