Viremia and virus shedding in elk infected with type 1 and virulent type 2 bovine viral diarrhea virus

In order to determine whether elk (Cervus elaphus) could be infected with and shed bovine viral diarrhea virus (BVDV) and to determine whether BVDV could cause disease in elk, two groups of five yearling elk each and two control cattle were experimentally inoculated intranasally with type 1 Singer strain or a virulent type 2 isolate of BVDV, strain 24515. Virulence of the type 2 isolate was confirmed by inoculation of a control bovine cow which developed diarrhea, dehydration, severe thrombocytopenia, hemorrhages, and enteritis with intestinal necrosis. None of the elk inoculated with type 1 or type 2 BVDV developed clinical signs of illness. However, all elk became infected as demonstrated by viremia, nasal shedding, and/or seroconversion. One uninoculated, in-contact elk contracted type 1 BVDV and seroconverted. Thus, although BVDV does not appear capable of producing disease in nonpregnant elk, the species is susceptible to infection and can shed and transmit BVDV.     

Histone deacetylase 6 regulates human immunodeficiency virus type 1 infection

Efficient human immunodeficiency virus (HIV)-1 infection depends on multiple interactions between the viral gp41/gp120 envelope (Env) proteins and cell surface receptors. However, cytoskeleton-associated proteins that modify membrane dynamics may also regulate the formation of the HIV-mediated fusion pore and hence viral infection. Because the effects of HDAC6-tubulin deacetylase on cortical alpha-tubulin regulate cell migration and immune synapse organization, we explored the possible role of HDAC6 in HIV-1-envelope-mediated cell fusion and infection. The binding of the gp120 protein to CD4+-permissive cells increased the level of acetylated alpha-tubulin in a CD4-dependent manner. Furthermore, overexpression of active HDAC6 inhibited the acetylation of alpha-tubulin, and remarkably, prevented HIV-1 envelope-dependent cell fusion and infection without affecting the expression and codistribution of HIV-1 receptors. In contrast, knockdown of HDAC6 expression or inhibition of its tubulin deacetylase activity strongly enhanced HIV-1 infection and syncytia formation. These results demonstrate that HDAC6 plays a significant role in regulating HIV-1 infection and Env-mediated syncytia formation.     

Altered cytokine production after human herpes virus type 6 infection.

Several strategies allow viruses to elude the surveillance of the immune system and to establish persistent infection in the host. One of such mechanisms is the immunosuppression caused by the direct infection and functional impairment of immune cells. Human Herpes virus type 6 (HHV-6) is a typical immunosuppressive agent, as suggested by its tropism for both CD4+ and CD8+ T cells, B cells, monocytes/macrophages, megakaryocytes and NK cells. In this study the production of IL-10 and IL-12 by peripheral blood mononuclear cells (PBMC) was evaluated during HHV-6 infection "in vitro". Our results demonstrate that HHV-6 up-regulates IL-10 production by PBMC. Furthermore, our data suggest that rhIFN gamma addition counteracts the effect of HHV-6 in promoting IL-10 release. To gain more insight into the role of IFN gamma, anti-IFN gamma monoclonal antibodies were added to PBMC stimulated with LPS. Neutralization of endogenous IFN gamma upregulated IL-10 release. Furthermore, HHV-6 infection inhibited IFN gamma release induced by LPS in PBMC. No basal production of IL-12 was found in PBMC. Moreover, HHV-6 infection did not induce IL-12 release by PBMC. On the contrary, IL-12 was detected in the supernatants of PBMC treated with LPS with or without rhIFN gamma. In these experimental conditions the further addition of HHV-6 markedly impaired IL-12 production. Moreover, the neutralization of IL-10 resulted in a significant up-regulation of IL-12. Finally our data suggest that the immunodysregulation induced by HHV-6 could be accounted for by a shift from a Th-1 to a Th-2 type cytokine profile.     

Viremia and serum antibodies in Syrian hamster after inapparent infection with European tick-borne encephalitis virus

1.) Adult Syrian hamsters (Cricetus auratus) are relatively insusceptible to the lethal affect of the ETBE virus after peripheral inoculation. After subcutaneous infection with 10(3) i. cer. mouse LD50 of the virus they manifest 25 per cent mortality. 2) In subcutaneously infected hamsters the virus is demonstrable in the CNS of only 20 per cent of the animals. CF- and VN-antibodies can be found in the blood from the 10th day; CF--antibodies culminate on the 20th-30th day receding relatively quickly, whereas VN-antibodies peak after the 28th day, dropping only partly and persisting. 3) The dynamics of CF- and VN-antibodies and a high number of clinically inapparent hamster infections resemble the situation in humans infected with ETBE under natural conditions.     

Viremia and serum antibodies in Macacus rhesus monkey after inapparent infection with European tick-borne encephalitis virus.

1. Inapparent infection was called forth in M. rhesus monkeys by means of subcutaneous inoculation of ETBE virus. 2. Viremia was found in 18 (86 per cent) of 21 monkeys. In all the 18 monkeys, specific virus-neutralizing antibodies were found; in 17 of them complement-fixing antibodies developed in addition. 3. Neutralizing antibodies (N greater than or equal to 1.7 log10) were first recorded on 10th day with a peak on 32nd day, retaining, after a small decrease, a relatively high level in all reacting animals. 4. Complement-fixing antibodies were first found on 18th day, showing a peak on 22nd day whereafter they dropped considerably or even disappeared so that on 150th day they were present in a low titre in only 35 per cent of the originally reacting monkeys. 5. The findings were compared with the situation in naturally infected humans and in hamsters infected inapparently (experimentally) with ETBE virus.     

Hepatitis B virus type 2 infection in France

Hepatitis B type 2 infection was observed in 96 French soldiers. A recent stay overseas was reported by 65% of them and an HBsAg chronic carrier state was observed in eight individuals. Anti-pre-S1 and anti-pre-S2 antibodies were not detected after recovery, but HBV DNA was detected in 58 % of sera tested.     

外泌体在人类免疫缺陷病毒1型感染中的研究进展

外泌体(exosome)是动物细胞在生理或病理条件下分泌到胞外的内生性纳米微囊,在疾病发生机制和药物运输载体等研究领域成为新宠。近年来发现,外泌体在人类免疫缺陷病毒1型(human immunodeficiency virus type 1,HIV-1)感染者体内能转移病毒组分和病毒相关免疫分子,与HIV-1感染密切相关。本文以外泌体介导的HIV-1感染机制为重点,围绕外泌体与HIV-1感染的关系进行综述。     

Dengue type 2 virus infection in human peripheral blood monocyte cultures

Dengue type 2 virus (D2V) infection in cultured human monocytes was studied. D2V permissiveness of the monocytes was enhanced when the cells were inoculated with D2V in the presence of either polyclonal or type-specific monoclonal anti-dengue antibody. The enhancement of D2V permissiveness mediated by the antibodies was more clearly demonstrated when the monocytes had been treated with trypsin before virus inoculation, though treatment of the cells with trypsin alone decreased D2V permissiveness. The enhancement of infection by type-specific neutralizing monoclonal antibody suggests that the D2V particles possess at least two antigenic determinants closely associated with virus infectivity. Infectious center assays revealed that the infection enhancement in the presence of the antibodies was due primarily to an increase in the number of D2V-infected cells, and that only a small proportion of the monocyte population supported D2V replication. The virus-permissive monocytes did not bear HLA-DR antigens on their cell surface. The presence of nonadherent lymphocytes in the monocyte cultures before D2V inoculation did not affect the D2V permissiveness of the monocytes. Treatment of cultured monocytes with the synthetic adjuvants N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) and its lipophilic derivative, [B30]-MDP, did not significantly affect the D2V permissiveness of the cells.     

Alkaline protease activity associated with iridescent virus type 6

Abstract An alkaline protease activity has been found to be associated with Iridovirus type 6. The enzyme showed a pH optimum of 10–10.5 with azocoll and hemoglobin but was essentially inactive on casein. From inhibitor studies the enzyme behaved like a serine protease. An M _r value of about 11500 was determined by SDS-PAGE.