Successful management of the first reported case in Austria of COVID-19 with ARDS.

We report the successful management of a patient with severe respiratory failure due to COVID-19 admitted to an intensive care unit complicated by secondary catheter-related infection of Candida glabrata. We are discussing some of the clinical challenges and the pitfalls in molecular diagnosis of SARS-CoV-2, including the fact that a positive PCR result may not always reflect infectiousness.

Quantitative determination of IgM antibodies reduces the pitfalls in the serodiagnosis of tick-borne encephalitis.

BACKGROUND: Tick-borne encephalitis (TBE) is the most important arbovirus disease in parts of Europe and Asia. Its laboratory diagnosis depends on the detection of specific IgM antibodies which can be impeded by (1) long-time persistence of IgM antibodies after infection, (2) vaccine-induced IgM antibodies, and (3) cross-reactive IgM antibodies from other flavivirus infections. OBJECTIVES: To assess the extent of interference factors in the serodiagnosis of TBE that might lead to the false positive assignment of a recent infection. STUDY DESIGN: We quantified TBE virus-specific IgM and IgG antibodies in sera collected at different time points from cohorts of (1) 61 TBE patients, (2) 131 TBE vaccinees, and (3) 42 patients with recent dengue or West Nile virus infections. RESULTS: All of the TBE patients were IgM- and IgG-positive upon hospitalization and 87% of acute TBE sera had IgM antibody titers of >500 Arbitrary Units (AU). These titers rapidly declined and only 16% of TBE patients had low IgM titers ≥9 months after infection. Vaccine-induced as well as flavivirus cross-reactive IgM antibodies were rarely detectable and of low titer. CONCLUSIONS: Most of the potential problems of TBE serodiagnosis can be resolved by the quantification of IgM antibodies in a single serum sample taken upon hospitalization. High IgM values (>500 AU in our assay) are indicative of a recent infection. Lower IgM values, however, may require the analysis of a follow-up sample and/or a specific neutralization assay to exclude the possibilities of IgM persistence, vaccine-induced IgM antibodies or heterologous flavivirus infections.

Human cytomegalovirus infection in lung transplant recipients triggers a CXCL-10 response.

Human cytomegalovirus (HCMV) causes significant morbidity in lung transplant recipients (LTRs). The clinical effects of HCMV replication are determined partly by a type 1 T-helper cell (Th1) response. Because the chemokine interferon-inducible protein of 10 kilodaltons (IP-10, CXCL-10) induces a Th1 response, we investigated whether HCMV triggers IP-10 in LTRs. The IP-10 concentration and HCMV DNA load were determined in 107 plasma and 46 bronchoalveolar lavage fluid (BALF) samples from 36 LTRs. Initial HCMV detection posttransplantation was significantly associated with increased plasma IP-10, regardless of whether the patients showed HCMV DNAemia (p = 0.001) or HCMV replication only in the allograft (p < 0.0001). In subsequent episodes of HCMV detection, plasma IP-10 increased regardless of whether HCMV was detected in blood (p = 0.0078) or only in BALF (p < 0.0001) and decreased after successful antiviral therapy (p = 0.0005). Furthermore, levels of HCMV DNA and IP-10 correlated statistically (p = 0.0033). Increased IP-10 levels in HCMV-positive BALF samples were significantly associated with severe airflow obstruction, as indicated by a decrease in forced expiratory volume in one second (FEV1). Our data indicate that HCMV replication in LTRs evokes a plasma IP-10 response and that, when an IP-10 response is observed in BALF, it is associated with inflammatory airway obstruction in the allograft.

Decreased interferon-gamma response in respiratory syncytial virus compared to other respiratory viral infections in infants.

An inappropriate interferon-gamma response has been implicated in the pathogenesis of severe respiratory syncytial virus (RSV) lower respiratory tract illness (LRTI). To assess whether this is unique for RSV primary LRTI compared to a first non-RSV LRTI, intracellular interferon-gamma was determined by flow cytometry in peripheral blood mononuclear cells from 32 infants with a primary RSV infection, 28 with a first non-RSV LRTI due to adenoviral, parainfluenzaviral and rhinoviral infection and 13 healthy infants. Interferon-gamma responses were increased significantly during adenoviral, parainfluenzaviral and the majority of the rhinoviral infections, but remained low during RSV and severe rhinoviral infection. Low interferon-gamma responses were associated with a more severe clinical course of LRTI. This indicates that depending on the nature of the viral pathogen, respiratory virus infections in infants differ significantly with regard to the quantity of the interferon-gamma production and that this may contribute to the clinical course of the disease.

A DNA immunization model study with constructs expressing the tick-borne encephalitis virus envelope protein E in different physical forms.

We have conducted a DNA immunization study to evaluate how the immune response is influenced by the physical structure and secretion of the expressed Ag. For this purpose, we used a series of plasmid constructs encoding different forms of the envelope glycoprotein E of the flavivirus tick-borne encephalitis virus. These included a secreted recombinant subviral particle, a secreted carboxyl-terminally truncated soluble homodimer, a nonsecreted full-length form, and an inefficiently secreted truncated form. Mice were immunized using both i.m. injection and Gene Gun-mediated application of plasmids. The functional immune response was evaluated by determining specific neutralizing and hemagglutination-inhibiting Ab activities and by challenging the mice with a lethal dose of the virus. As a measure for the induction of a Th1 and/or Th2 response, we determined specific IgG subclasses and examined IFN-gamma, Il-4, and Il-5 induction. The plasmid construct encoding a secreted subviral particle, which carries multiple copies of the protective Ag on its surface, was superior to the other constructs in terms of extent and functionality of the Ab response as well as protection against virus challenge. As expected, the type of Th response was largely dependent on the mode of application (i.m. vs Gene Gun), but our data show that it was also strongly influenced by the properties of the Ag. Most significantly, the plasmid encoding the particulate form was able to partially overcome the Th2 bias imposed by the Gene Gun, resulting in a balanced Th1/Th2 response.

Reduced interferon-gamma expression in peripheral blood mononuclear cells of infants with severe respiratory syncytial virus disease.

We examined the in vivo cell-mediated immune response in infants with respiratory syncytial virus (RSV) infection in order to gain information about the pathogenesis of severe RSV disease in infancy. Semiquantitative reverse transcription-polymerase chain reaction and three-color flow cytometry were used to determine the levels of messenger RNA (mRNA) for interferon (IFN)-gamma in peripheral blood mononuclear cells, and the distribution of lymphocyte subsets in infants with acute RSV infection. The findings were correlated with the severity of the patients' illness and the production of RSV-specific IgE antibodies (RSV-IgE). Significantly lower IFN-gamma levels and T-lymphocyte counts in the acute phase of illness were observed in infants with severe RSV disease than in those with a milder clinical course of illness. The induction of RSV-IgE was not related to IFN-gamma levels in the acute phase of illness, but rather correlated with IFN-gamma expression during convalescence. The data indicate that reduced IFN-gamma expression may be an important factor in the pathogenesis of severe RSV disease in infancy.

Nephropathia epidemica and Puumala virus in Austria.

To study the epidemiology of hantavirus infections in Austria, 1215 humans and 596 rodents of different species were tested for the presence of antibodies against Puumala and Hantaan virus. Direct virus identification by polymerase chain reaction in lung tissue of serologically positive rodents was performed to verify antibody results and to determine the genetic identity of viral RNA by phylogenetic analysis of a part of the hantavirus M segment. For 32 of the 37 cases of nephropathia epidemica diagnosed in Austria, the location where transmission took place could be traced to specific areas in the Austrian federal states of Carinthia and Styria. The overall seroprevalence in humans was 1.2% and ranged from 0.02% in Villach, Carinthia, to 0.8% in Korneuburg, Lower Austria, and 1.8% in Wolfsberg, Carinthia. Virus RNA could be amplified from three Clethrionomys glareolus voles collected in Klippitztörl, Carinthia, and from one collected in Ernstbrunn, Lower Austria. The sequences were all identified as Puumala virus by phylogenetic analysis and were found to be most closely related to the western European Puumala viruses from Germany and France. No evidence of the existence of Hantaan-like infections and viruses in Austria was found.

In vitro-synthesized infectious RNA as an attenuated live vaccine in a flavivirus model.

Live virus vaccines have in many cases proven to be an extremely effective tool for the prevention of viral diseases. However, the production of conventional live vaccines in eukaryotic cell cultures has many disadvantages, including the potential for contamination with adventitious agents and genetic alterations during propagation, making it necessary to do extensive testing before distribution. Based on results obtained with a flavivirus (tick-borne encephalitis virus) in an experimental animal system, we propose a novel live attenuated virus vaccination strategy consisting of the application of in vitro-synthesized infectious RNA instead of the live virus itself. When administered using the GeneGun, less than 1 ng of RNA was required to initiate replication of virus that was attenuated by a specifically engineered deletion and this induced a protective immunity in laboratory mice. Because this approach uses RNA, it does not have the potential drawbacks of DNA vaccines and thus combines the advantages of conventional live virus vaccines (for example, mimicking natural infection and inducing long-lasting immunity) with those of nucleic acid-based vaccines (for example, ease of production without a requirement for eukaryotic cell culture, stability and purity).