[Antiviral effects of the combination of glycyrrhizin and ribavirin against influenza A H1N1 virus infection in vivo].

Ribavirin is a broad-spectrum antiviral agent and glycyrrhizin has activities of anti-inflammation, immunoregulation and anti-viral infections. To enhance antiviral efficacy and weaken side-effects of ribavirin, antiviral effects of the combination of glycyrrhizin and ribavirin were studied in the present study. Firstly, a mouse model of viral pneumonia was established by inoculation of influenza H1N1 virus. Protective effects of glycyrrhizin and ribavirin used alone or in combination against H1N1 virus infection in mice were evaluated based on the survival rate, lung index and virus titer in lungs of mice. Results showed that the combination of glycyrrhizin and ribavirin significantly inhibited the lung consolidation with a 36% inhibition ratio on the lung swell of infected mice. The combination of the two drugs exhibited synergetic effects on survival of infected mice. The combination of 50 mg · kg(-1) · d(-1) glycyrrhizin and 40 mg · kg(-1) · d(-1) ribavirin resulted a 100% protection for infected mice with a synergetic value of 36, which was significantly higher than the control group and each drug alone. This combination also resulted a significant drop of lung virus titer (P < 0.01), as well as inhibition on the production of proinflammatory cytokines IL-6 (P < 0.01), TNF-α (P < 0.01) and IL-1ß (P < 0.05) induced by virus infection compared to the control. The treatment of ribavirin plus glycyrrhizin was more effective in influenza A infection in mice than either compound used alone, which suggested a potential clinical value of the combination of the two agents.

Tissue distribution of sialic acid-linked influenza virus receptors in beagle dogs.

Reports of influenza A virus infections in dogs has received considerable attention from veterinarians, virologists, and epidemiologists. Interaction between influenza viral hemagglutinin and cell oligosaccharides containing sialic acid residues results in infection. Sialic acids have an α-2,3-linkage to the penultimate galactose in the avian influenza virus receptor and an α-2,6-linkage in the human receptor. To date, there are no detailed data on the tissue distribution or histological features of either type of sialic acid-linked influenza virus receptors in beagle dogs, which are common laboratory animals and pets. We conducted the current study to visualize the in situ tissue distribution of both sialic acid-linked influenza virus receptors in various organs of beagle dogs using Maackia amurensis lectin II and Sambucus nigra agglutinin. Both α-2,3- and α-2,6-sialic acid-linked receptors were detected in the endothelial cells of the respiratory tract and other organs. Endothelial cells of most gastrointestinal organs were negative for α-2,3-sialic acid-linked receptors in the dogs. Our results suggested that these canine organs may be affected by influenza virus infection. The findings from our study will also help evaluate the occurrence and development of influenza virus infections in dogs.

Na+/H+ exchanger 1 gene expression in tissues of yellow chicken.

The Na(+)/H(+) exchanger 1 (NHE1) transmembrane protein regulates intracellular pH, cell survival, cell growth, cell differentiation and plays a critical role in the progression of some diseases, including the pathogenesis of J avian leukosis. The chicken is an ideal model to study the function of NHE1 because it has developed highly efficient Na(+)-absorptive mechanisms in its small and large intestines. To date, there has been no detailed expression analysis to determine NHE1 expression in various tissues of the chicken. We determined the mRNA and protein expression levels of avian NHE1 by real-time quantitative PCR and immunohistochemical analysis. NHE1 mRNA was detected in all chicken tissues examined. Protein expression levels varied widely among tissues and did not always correlate with mRNA expression. Determining the mRNA and protein of NHE1 expression patterns in chicken should help to delineate the NHE1 role in different tissues and its contribution to physiological and pathological processes. These data provide the basis for examining the distinct function of chicken NHE1 compared with its mammalian counterpart.

An ALV-J isolate is responsible for spontaneous haemangiomas in layer chickens in China.

Subgroup J avian leukosis virus (ALV-J), first isolated in 1989, mainly induces tumours of myeloid leukosis (ML) in meat-type chickens. In 2006, ALV-J strain SCAU-HN06 was isolated from commercial layer hens with spontaneous haemangiomas in China. To confirm its role in the induction of haemangioma, we constructed a full-length copy of the proviral genome from SCAU-HN06, recovered virus from DF-1 cells detected by enzyme-linked immunosorbent assay, characterized its growth property and investigated its pathogenicity. The recovered virus appeared to be identical to SCAU-HN06 analysed by both blast gene sequences and indirect immunofluorescence assay. It also showed similarities in growth to the parental wild-type virus in vitro. The pathogenicity of the rescued and parental virus in specific-pathogen-free White Leghorn chickens was investigated. Both SCAU-HN06 and rSCAU-HN06 could induce haemangioma, with incidence of 52% and 42.8% respectively. Overall, our findings indicated that the ALV-J strain SCAU-HN06 was the causal agent inducing haemangiomas rather than ML in certain layer chickens.

Quantification of prion gene expression in brain and peripheral organs of golden hamster by real-time RT-PCR.

Determination of tissue-specific expression of cellular prion protein (PrPc) is essential for understanding its poorly explained role in organisms. Herein we report on quantification of PrP mRNA in golden hamsters, a popular experimental model for studying mechanisms of transmissible spongiform encephalopathies (TSE), by real-time RT-PCR. Total RNA was isolated from four different regions of the brain and six peripheral organs of eight golden hamsters. PrP mRNA copy numbers were determined using absolute standard curve method with real-time quantitative PCR instrument. It was found that high mRNA levels were present in all four regions of the brain examined, including obex, neocortex, cerebellum, and thalamus. In peripheral organs examined, inguinal lymph node showed high level of the expression similar to that in overall brain; spleen, heart, liver, and lung showed moderate levels of the expression; and kidney showed the lowest expression. Our result is consistent with the potential involvement of different organs in prion diseases and offers essential data for further study of TSE mechanism in this animal model.

Comparative analysis of the prion protein open reading frame nucleotide sequences in peacock and parakeet.

The open reading frame of peacock and parakeet prion protein (PrP) genes was cloned and sequenced. The peacock and parakeet PrP genes consisted of 833 and 866 nucleotides encoding 266 and 277 amino acids, respectively (GenBank Accession numbers AY365065 and AY365066). Sequence analysis showed that the peacock and parakeet PrP genes had 93.67% homology to each other, 94.04% and 99.64% homology to the chicken PrP gene and 46.0% and 42.1% similarity to the mammalian PrP genes, respectively. The structural features of all known mammalian and avian PrPs, including N-terminal signal peptides, tandem repeats, conserved hydrophobic region, disulfide bridges and glycoinositol phospholipid anchor, were also found in peacock and parakeet PrPs. The parakeet and peacock PrPs, however, differed in the hexarepeat region, with the peacock having six and the parakeet having seven hexarepeats. The phylogenetic analysis showed that the PrP genes in 52 species were clustered into 2 distinct lineages, the avian and the mammalian. The peacock and parakeet PrP genes belonged to the same lineage but the peacock PrP was sub-classed with the pigeon PrP and the parakeet PrP was sub-classed with the duck and chicken PrPs. The present work added two more species data to the collection of the PrP genes and supported the previous findings that the PrP genes are highly conserved across species.

Altered expression of the prion gene in rat astrocyte and neuron cultures treated with prion peptide 106-126.

Neuronal degeneration and astrogliosis are hallmarks of prion disease. Synthetic prion protein (PrP) peptide 106-126 (PrP106-126) can induce death of neurons and proliferation of astrocytes in vitro and this neurotoxic effect depends on the expression of cellular PrP (PrPC) and is hence believed to be PrP(C) -mediated. To further elucidate the involvement of PrPC in PrP106-126-induced neurotoxicity, we determined the expression of PrP mRNA in primary culture of rat cortical neuron cells, cerebellar granule cells, and astrocytes following treatment with 50 microM of PrP106-126 scrambled PrP106-126 by quantitative real-time RT-PCR. As shown by MTT test, PrP106-126 induced significant death of neuron cells and marked proliferation of astrocytes after 10 days of treatment. Under the same treatment regimens, the level of PrP gene expression was significantly down-regulated in cortical neuron cell cultures and cerebellar granule cell cultures and was up-regulated in astrocyte cultures. The altered PrP gene expression occurred as early as 3 days after the treatment. After 10 days of treatment, while the cultured cortical neurons underwent further apoptosis, their expression of PrP gene started to recover gradually. These findings indicate that PrP 106-126 regulates transcription of the PrP gene and this activity is associated with its neurotoxicity in primary rat neuronal cultures.

[A study on pathological changes of brain after high +Gx exposure in rhesus monkey].

OBJECTIVE: To study the pathological morphological changes of cerebral cortex and hippocampi in rhesus monkey caused by +Gx exposure, and to explore the relation between +Gx level and pathological changes. METHOD: Healthy rhesus monkeys were randomly divided into one control group and three experimental groups (+15 Gx, +18 Gx, +21 Gx). Monkeys in each group were exposed to the corresponding level of +Gx, after that, the required tissue was qualitatively studied on the basis of pathological morphology. RESULT: 1) Different morphology changes were observed in pyramidal neurons and astrocytes in the cerebral cortex and hippocampi by light microscopy. The higher the +Gx level, the more the changes were observed. In addition, the trauma was more serious in the hippocampi. 2) Chromatin marginating, karyotheca fold, apoptosis body and swollen mitochondria with blurred cristae were observed in pyramidal cell under electron microscope after +Gx exposure, and degenerative changes were also observed in some cases after higher +Gx. CONCLUSION: High level of +Gx causes acute pathological trauma of brain tissues in rhesus monkey, and consanguineous relationship exists between pathological changes and level of +Gx.