textabstractRabies is an important neglected disease, characterized by invariably fatal encephalitis. Several studies focus on understanding the pathogenic mechanisms of the prototype lyssavirus rabies virus (RABV) infection, and little is known about the pathogenesis of rabies caused by other lyssaviruses. We sought to characterize the host response to Duvenhage virus infection and compare it with responses observed during RABV infection by gene expression profiling of brains of mice with the respective infections. We found in both infections differentially expressed genes leading to increased expression of type I interferons (IFNs), chemokines, and proinflammatory cytokines. In addition several genes of the IFN signaling pathway are up-regulated, indicating a strong antiviral response and activation of the negative feedback mechanism to limit type I IFN responses. Furthermore we provide evidence that in the absence of significant neuronal apoptotic death, cell death of neurons is mediated via the pyroptotic pathway in both infections. Taken together, we have identified several genes and/or pathways for both infections that could be used to explore novel approaches for intervention strategies against rabies.

Influenza vaccination recommendations for swine While humans have taken the approach of annual vaccine strain updates in attempts to minimize influenza illness and death, control of influenza in swine herds has been less flexible. Vaccination of swine with killed virus vaccines has been employed with varying degrees of success since the mid-1990s. As more strains of SIV emerged, biological companies have added contemporary strains to their existing, commercially licensed vaccines, resulting in bivalent and trivalent vaccines carefully balanced to induce immunity to all subtypes of SIV in the vaccine. Alternatively, autogenous killed influenza virus vaccines have gained in popularity to better match the antigenic and genetic differences of new SIV strains when compared to the commercial vaccine virus strains. A change in vaccine strain is generally recommended when issues such as antigenic correctness, timing, adjuvant, and co-infections have been properly addressed. More often, the decision to use an autogenous vaccine is driven by a need to more immediately respond with a specific and rapid solution to the problems unsolved by the use of commercial vaccines.

Zusammenfassung Sereuze of mucopurulente neusuitvloed, passagebelemmering, minimale algemene verschijnselen; meestal geen koorts.

Human metapneumovirus (hMPV) was first described in Dutch children with acute respiratory symptoms. A prospective analysis of the epidemiology, clinical manifestation, and seroprevalence of hMPV and other respiratory viruses in South African children referred to hospital for upper or lower respiratory tract infection were carried out during a single winter season, by using RT-PCR, viral culture, and enzyme-linked immunosorbent assays. In nasopharyngeal aspirates from 137 children, hMPV was detected by RT-PCR in 8 (5.8%) children (2-43 months of age) as a sole viral pathogen, respiratory syncytial virus (RSV) in 21 (15%), influenza A virus in 18 (13%) and influenza B virus in 20 (15%). Pneumonia was diagnosed in seven children and upper respiratory tract infection in one of the hMPV-infected children. One hMPV-infected child was admitted to the intensive care unit in need of mechanical ventilation and one child was infected with human immunodeficiency virus (HIV). No statistically significant differences were found between hMPV, RSV, and influenza virus infected groups with regard to clinical signs and symptoms and chest radiograph findings. The seropositive rate of hMPV specific IgG antibodies was 92% in children aged 24-36 months, the oldest seronegative child in our study was 7 years and 6 months of age. In conclusion, hMPV contributes to upper and lower respiratory tract morbidity in South African children.

During the outbreak of highly pathogenic avian influenza (HPAI) A(H7N7) in the Netherlands in 2003, human infection occurred in unexpectedly high numbers. Initially, all those involved in the culling of poultry were advised to wear protective clothing, goggles, and nose–mouth masks, and to wash their hands after work. In a later stage, vaccination and antiviral prophylaxis of all poultry workers and antiviral treatment of all cases was initiated. Case finding was implemented immediately. Conjunctival and nose/throat swabs were collected from 453 persons. Eighty-nine persons were A(H7) positive, 78 with conjunctivitis only, 5 with conjunctivitis and influenza-like illness (ILI), 2 with ILI only and 4 did not fit the case definitions. Nine A(H7) cases had both positive conjunctival and nose/throat swabs. One A(H7) case had an A(H7) positive nose/throat swab only. Of the two A(H7) cases presenting with ILI only, a veterinarian who developed a respiratory distress syndrome died. Three contacts of two A(H7) positive poultry workers developed A(H7) conjunctivitis. One of these, the 12-year-old daughter of a poultry worker, additionally developed ILI. Since they had no direct exposure to infected poultry, these observations strongly suggest human-to-human transmission. No simultaneous infection with A(H7) and human influenza virus in one patient was detected.

RATIONALE:The Dutch VIGALL (virally mediated allergy) study investigates the role of viral upper respiratory tract infections (URTI) on maturation of the immune system and development of allergic disease.Here we investigate the prevalence of viral respiratory pathogens and changes in the immune response related to the age of children.METHODS: Hundred twenty-six infants were included at birth.Nasal brush samples were taken during routine visits every 6 months and during URTI up to the age of the two years.The type of virus, number of effector cells (macrophages, T-lymphocytes), and mediators cells (Th 1 and Th2 cytokine positive) in relation to the age of the child were determined.RESULTS: The most common viral pathogens during URTI were rhinovirus (-40%), RSV (~20%), and coronavirus (~10%).Surprisingly, 20% of infants without nasal symptoms were rhinovirns positive.Numbers of macrophages (CD68) in healthy controls remained constant with age, where the numbers increased during RSV or rhinovirus URTI.Numbers of T-lymphocytes (CD3) increased with age, both during viral infection and in healthy controls.Additionally, a decrease in numbers of IL-4 and IL-10 positive cells (Th2) was observed with increasing age of healthy controls, while the number of IL-12 positive cells (Th 1) remained constant.T-lymphocyte and IL-4 responses remained related to the age when adjusted for the number of respiratory infections.CONCLUSIONS: Our data show the maturation of the nasal immune system in children.Based on initial data we suggest that the maturation is ' age-related rather than infection-related.

The first sign of influenza activity in the Netherlands during the 2005-2006 influenza season was the isolation of influenza viruses in the last week of 2005. From Week 1 of 2006 onwards, an increase in clinical influenza activity was also observed that did not return to baseline levels until Week 15. Two waves of influenza activity were observed with peak incidences of 13.8 and 9.8 influenza-like illnesses per 10,000 inhabitants on Weeks 7 and 12, respectively. The first wave of influenza was caused primarily by influenza B viruses, whereas the second wave was caused predominantly by influenza A/H3N2 viruses. The influenza B viruses appeared to belong to two different phylogenetic lineages and were antigenically distinguishable from the vaccine strain. The isolated influenza A/H3N2 viruses were closely related to the vaccine strain for this subtype and only minor antigenic differences with the vaccine strain were observed for a limited number of isolates. Only a small number of influenza A/H1N1 viruses were isolated, which all closely resembled the H1N1 vaccine strain. For the 2006-2007 influenza season, the World Health Organization has recommended the following vaccine composition: A/Wisconsin/67/05 (H3N2), A/New Caledonia/20/99 (H1N1) and B/Malaysia/2506/05.

Virus-associated mass mortalities among seals inhabiting northwestern Europe have generated an interest in immunotoxicology in this species. A morbillivirus has been isolated from victims, but a contribution of immunotoxic contaminants to the severity of the outbreaks could not be ruled out. Fish-eating seals occupy high trophic levels in the aquatic food chain, and accumulate high levels of contaminants including polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs). Such chemicals have been found to be immunotoxic at low doses in studies of laboratory animals. We carried out an immunotoxicological study, in which captive harbor seals (Phoca vitulina) were fed herring from either relatively uncontaminated sites of the Atlantic Ocean, or from the highly contaminated Baltic Sea. In this report we summarize the contaminant-related immunosuppression observed in the captive group of seals fed herring from the Baltic Sea. In addition, we describe two parallel studies, in which laboratory rats are exposed as adults or perinatally to the contaminants in the Baltic Sea herring, exhibiting immunotoxicity. On the basis of these studies we conclude that complex mixtures of environmental contaminants including PCBs, PCDFs, and PCDDs may represent a real immunotoxic risk to free-ranging seals. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.

We have used the mouse model to monitor the acquisition of virulence of a non-pathogenic influenza A virus upon adaptation to a new mammalian host. An avian strain, A/Mallard duck/Pennsylvania/10218/84 (H5N2) (Mld/PA/84) was adapted to mice by 23 serial lung-to-lung passages until a highly virulent mouse-adapted (MA) variant (Mld/PA/84-MA) emerged. This MA variant was characterized and compared to the parental strain as well as some of its intermediate passage variants. MA variant caused bronchopneumonia in mice with a high mortality rate (the virulence of Mld/PA/84-MA measured as log (EID50/LD50) was 1.75), while the parental, avirulent strain Mld/PA/84 did not cause illness and mortality in mice (log (EID50/LD50) was 7.25). Hemagglutination-inhibition (HAI) test with a set of hemagglutinin- (HA) specific monoclonal antibodies (MAbs) revealed antigenic differences between the parental strain and MA variant. Mld/PA/84-MA reacted with HA-specific MAbs in higher titers than the parental strain. The HA genes of the parental strain Mld/PA/84, the 1st, 3rd, 8th, and 15th intermediate passage variants, and Mld/PA/84-MA were sequenced. Three amino acid changes at positions 203, 273 and 320 were determined in the HA of MA variant. The first of them, Leu-->Pro (320), appeared in the HA stem region at the 8th passage. Two other in the HA1 globular region (Ser-->Phe (203) and Glu-->Gly (273)) appeared at the 15th passage. All of these substitutions were associated with the increase of viral infectivity for mouse lungs and changes in the HA antigenicity. The potential role of these changes in HA with respect to the process of viral interspecies transmission and acquisition of virulence for new host is discussed.

OBJECTIVE:To assess the source of HIV-1 production in lymphoid tissue biopsies from HIV-infected patients, with no prior anti-retroviral protease inhibitor treatment, with a CD4 cell count > 150 x 10(6)/l (group I) or < 50 x 10(6)/l (group II), co-infected with Mycobacterium tuberculosis or Mycobacterium avium complex.DESIGN AND METHODS:Lymphoid tissue biopsies from 11 HIV-1-infected patients, taken for diagnostic purposes, were studied by HIV-1 RNA in situ hybridization and immunohistochemistry.RESULTS:Patients of group I showed well organized granulomas, in contrast with patients of group II, in which granuloma formation was absent. HIV-1 RNA-positive cells in group I patients were found mainly around the granulomas, whereas in group II HIV-1-producing cells were confined to areas with remaining intact lymphoid tissue. Despite the abundant presence of macrophages, the productively infected HIV-1-positive cells in both groups were almost exclusively CD4 T cells.CONCLUSION:In contrast with previously published data, CD4 T cells appear to remain the major source of HIV-1 production in end-stage disease.

In this paper we describe the effect of depletion of splenic macrophages on the uptake, and immune response against, different formulations of rabies virus antigen. Splenic macrophages were removed by intravenous injection with clodronate liposomes. β‐propiolacton inactivated rabies virus (RV‐BPL) and immune‐stimulating complexes (iscom) containing these antigens were given to macrophage‐depleted and control mice. In the absence of phagocytic cells in the spleen, antigen is still trapped in the red pulp and to a lesser extent in the peri‐arteriolar lymphocyte sheaths (PALS) for both antigen formulations. The localization pattern in the main area of immune response induction, namely the follicles, was unaltered after macrophage depletion. Functionally, the depletion of splenic and liver macrophages had no influence on the induction of specific antibody responses in both RV‐BPL or RV‐iscom immunized mice, even though the latter presentation form was clearly associated with specific localization in the marginal metallophillic macrophages. In RV‐BPL immunized mice, macrophage depletion had no influence on proliferative T‐cell responses. However, macrophage‐depleted mice that were immunized with RV‐iscom showed a significant decrease in proliferative T‐cell responses. These results confirm existing ideas on the spleen as a physical filter rather than an induction site for humoral responses and shed new light on the efficient role of iscoms as antigen‐presenting moieties in relation to their specific in vivo localization patterns and partial macrophage dependency.

Natural killer (NK) activity, an important non-specific defense mechanism against viral infections and tumors, was demonstrated in beluga whales using two different methods: 51Cr release and flow cytometry. Using the 51Cr release assay, NK activity in belugas was shown to be higher against K-562 than against YAC-1 cell lines. Moreover, it was enhanced by the addition of human recombinant interleukin-2 with both cell lines. NK activity evaluated by flow cytometry in the peripheral blood of eight belugas increased when the effector:target cell (E:T) ratio increased, and averaged 13.9% ± 3.8% (range 9.9% to 17.8%) at an E:T ratio of 100:1. While NK activity could be readily detected using both methods, the lack of radio-isotopes and related laboratory room make the flow cytometric method a viable and safe alternative. The evaluation of this function in cetaceans could lead to better understanding of the early events that lead to viral epizootics in populations of marine mammals in different parts of the world, as well as to the high prevalence of neoplasms in St. Lawrence beluga whales.

Recently, conflicting data have been published about the ability of antibodies which efficiently neutralize T cell-adapted human immunodeficiency virus type 1 (HIV-1) strains to neutralize primary HIV-1 strains in vitro and in vivo. Here we present data indicating that such antibodies fail to neutralize primary HIV-1 strains in vivo. To this end, a newly developed chimeric human-to-mouse model was used, in which several aspects of primary HIV-1 infection are mimicked. Poly- and monoclonal anti-bodies protected the grafted human cells, in a dose-dependent way, from infection with T cell-adapted HIV-1 in this system. A human monoclonal antibody specific for the CD4 binding domain that efficiently neutralizes HIV-1 IIIB in vitro did not protect the human graft from HIV-1 IIIB infection. None of the antibodies provided protection in the in vivo model against infection with primary HIV-1 strains, although they were able to neutralize these same strains in vitro.

Potency control of inactivated rabies vaccines for human and veterinary application is usually undertaken by vaccination-challenge tests (e.g. the mouse potency test). For practical and ethical reasons there is an urgent need to replace in vivo potency control procedures, at least in part, by reliable methods of in vitro potency testing. Quantitative ELISA systems for potency control were developed using monoclonal antibodies (MAbs) directed to the glycoprotein (GP) and to the nucleoprotein (NP) of the virus. Although immuno-capture and competition ELISAs for GP measurement had almost equal sensitivity (detection level GP < 0.1 IU), the competition data showed the best correlation with potency values when a panel of rabies vaccines for human use was tested (r = 0.88, n = 10). The NP values for this panel of vaccines in the competition system (detection level NP < 1 IU) also correlated well with potency values (r = 0.90, n = 10). The competition system proved to be best also with liquid adjuvanted veterinary rabies vaccines of LEP, PM, PV and SAD origin. The implementation of ELISA systems for potency control of rabies vaccines is discussed.

Sequence analysis of the haemagglutinin protein (H) gene of the morbillivirus (PDV-2) isolated from a Siberian seal (Phoca sibirica) during the 1987/1988 epizootic in Lake Baikal revealed that it was most closely related to two recent isolates of canine distemper virus (CDV) from Germany and different from CDV vaccines currently in use in that region. The virus continued to circulate in seals in Lake Baikal after the 1987/1988 epizootic since sera collected from culled seals in the spring of 1992 were positive in morbillivirus ELISA tests, reacting most strongly with the CDV antigen.