Astrocytes evoke a robust IRF7-independent type I interferon response upon neurotropic viral infection.

BACKGROUND: Type I interferons (IFN-I) are fundamental in controlling viral infections but fatal interferonopathy is restricted in the immune-privileged central nervous system (CNS). In contrast to the well-established role of Interferon Regulatory Factor 7 (IRF7) in the regulation of IFN-I response in the periphery, little is known about the specific function in the CNS. METHODS: To investigate the role for IRF7 in antiviral response during neurotropic virus infection, mice deficient for IRF3 and IRF7 were infected systemically with Langat virus (LGTV). Viral burden and IFN-I response was analyzed in the periphery and the CNS by focus formation assay, RT-PCR, immunohistochemistry and in vivo imaging. Microglia and infiltration of CNS-infiltration of immune cells were characterized by flow cytometry. RESULTS: Here, we demonstrate that during infection with the neurotropic Langat virus (LGTV), an attenuated member of the tick-borne encephalitis virus (TBEV) subgroup, neurons do not rely on IRF7 for cell-intrinsic antiviral resistance and IFN-I induction. An increased viral replication in IRF7-deficient mice suggests an indirect antiviral mechanism. Astrocytes rely on IRF7 to establish a cell-autonomous antiviral response. Notably, the loss of IRF7 particularly in astrocytes resulted in a high IFN-I production. Sustained production of IFN-I in astrocytes is independent of an IRF7-mediated positive feedback loop. CONCLUSION: IFN-I induction in the CNS is profoundly regulated in a cell type-specific fashion.

Contact-dependent transmission of Langat and tick-borne encephalitis virus in type I interferon receptor-1 deficient mice.

Tick-borne encephalitis virus (TBEV) is primarily transmitted to humans through tick bites or oral consumption of accordingly contaminated unpasteurized milk or milk products. The detection of TBEV RNA in various body fluids in immunosuppressed human patients is documented. However, the risk of direct contact exposure remains unclear. Interferon-alpha receptor-1 deficient (Ifnar1-/- ) mice, which are lacking the interferon-α/ß responses, develop neurologic manifestations after infection with TBEV and Langat virus (LGTV). We showed that subcutaneous, intranasal, and peroral infection of LGTV lead to disease, whereas mice with intragastric application of LGTV showed no disease signs. With LGTV infected mice exhibit seroconversion and significant viral RNA levels was detected in saliva, eye smear, feces and urine. As a result, TBEV and LGTV are transmitted between mice from infected to naïve co-caged sentinel animals. Although intranasal inoculation of LGTV is entirely sufficient to establish the disease in mice, the virus is not transmitted by aerosols. These pooled results from animal models highlight the risks of exposure to TBEV contaminants and the possibility for close contact transmission of TBEV in interferon-alpha receptor-1 deficient laboratory mice.Importance Tick-borne encephalitis is a severe disease of the central nervous system caused by the tick-borne encephalitis virus (TBEV). Every year between 10,000-12,000 people become infected with this flavivirus. The TBEV is usually transmitted to humans via the bite of a tick, but infections due to consumption of infectious milk products are increasingly being reported. Since there is no therapy for an TBEV infection and mechanisms of virus persistence in reservoir animals are unclear, it is important to highlight the risk of exposure to TBEV contaminants and know possible routes of transmission of this virus. The significance of our research is in identifying other infection routes of TBEV and LGTV, and the possibility of close contact transmission.

Langat virus infection affects hippocampal neuron morphology and function in mice without disease signs.

BACKGROUND: Tick-borne encephalitis virus (TBEV) is an important human pathogen that can cause the serious illness tick-borne encephalitis (TBE). Patients with clinical symptoms can suffer from severe meningoencephalitis with sequelae that include cognitive disorders and paralysis. While less than 30% of patients with clinical symptoms develop meningoencephalitis, the number of seropositive individuals in some regions indicates a much higher prevalence of TBEV infections, either with no or subclinical symptoms. The functional relevance of these subclinical TBEV infections and their influence on brain functions, such as learning and memory, has not been investigated so far. METHODS: To compare the effect of low and high viral replication in the brain, wildtype and Irf-7-/- mice were infected with Langat virus (LGTV), which belongs to the TBEV-serogroup. The viral burden was analyzed in the olfactory bulb and the hippocampus. Open field, elevated plus maze, and Morris water maze experiments were performed to determine the impact on anxiety-like behavior, learning, and memory formation. Spine density of hippocampal neurons and activation of microglia and astrocytes were analyzed. RESULTS: In contrast to susceptible Irf-7-/- mice, wildtype mice showed no disease signs upon LGTV infection. Detection of viral RNA in the olfactory bulb revealed CNS infections in wildtype and Irf-7-/- mice. Very low levels of viral replication were detectable in the hippocampus of wildtype mice. Although wildtype mice develop no disease signs, they showed reduced anxiety-like behavior and impaired memory formation, whereas Irf-7-/- mice were not affected. This impairment was associated with a significant decrease in spine density of neurons in the hippocampal CA1 region of wildtype mice. Microglia activation and astrogliosis were detected in the hippocampus. CONCLUSION: In this study, we demonstrate that subclinical infections by viruses from the TBEV-serogroup affected anxiety-like behavior. Virus replication in the olfactory bulb induced far-reaching effects on hippocampal neuron morphology and impaired hippocampus-dependent learning and memory formation.

The envelope protein of tick-borne encephalitis virus influences neuron entry, pathogenicity, and vaccine protection.

BACKGROUND: Tick-borne encephalitis virus (TBEV) is considered to be the medically most important arthropod-borne virus in Europe. The symptoms of an infection range from subclinical to mild flu-like disease to lethal encephalitis. The exact determinants of disease severity are not known; however, the virulence of the strain as well as the immune status of the host are thought to be important factors for the outcome of the infection. Here we investigated virulence determinants in TBEV infection. METHOD: Mice were infected with different TBEV strains, and high virulent and low virulent TBEV strains were chosen. Sequence alignment identified differences that were cloned to generate chimera virus. The infection rate of the parental and chimeric virus were evaluated in primary mouse neurons, astrocytes, mouse embryonic fibroblasts, and in vivo. Neutralizing capacity of serum from individuals vaccinated with the FSME-IMMUN® and Encepur® or combined were evaluated. RESULTS: We identified a highly pathogenic and neurovirulent TBEV strain, 93/783. Using sequence analysis, we identified the envelope (E) protein of 93/783 as a potential virulence determinant and cloned it into the less pathogenic TBEV strain Torö. We found that the chimeric virus specifically infected primary neurons more efficiently compared to wild-type (WT) Torö and this correlated with enhanced pathogenicity and higher levels of viral RNA in vivo. The E protein is also the major target of neutralizing antibodies; thus, genetic variation in the E protein could influence the efficiency of the two available vaccines, FSME-IMMUN® and Encepur®. As TBEV vaccine breakthroughs have occurred in Europe, we chose to compare neutralizing capacity from individuals vaccinated with the two different vaccines or a combination of them. Our data suggest that the different vaccines do not perform equally well against the two Swedish strains. CONCLUSIONS: Our findings show that two amino acid substitutions of the E protein found in 93/783, A83T, and A463S enhanced Torö infection of neurons as well as pathogenesis and viral replication in vivo; furthermore, we found that genetic divergence from the vaccine strain resulted in lower neutralizing antibody titers in vaccinated individuals.

Correlation of Severity of Human Tick-Borne Encephalitis Virus Disease and Pathogenicity in Mice.

We compared 2 tick-borne encephalitis virus strains isolated from 2 different foci that cause different symptoms in tick-borne encephalitis patients, from neurologic to mild gastrointestinal symptoms. We compared neuroinvasiveness, neurovirulence, and proinflammatory cytokine response in mice and found unique differences that contribute to our understanding of pathogenesis.

Evaluation of the Parasight Platform for Malaria Diagnosis.

The World Health Organization estimates that nearly 500 million malaria tests are performed annually. While microscopy and rapid diagnostic tests (RDTs) are the main diagnostic approaches, no single method is inexpensive, rapid, and highly accurate. Two recent studies from our group have demonstrated a prototype computer vision platform that meets those needs. Here we present the results from two clinical studies on the commercially available version of this technology, the Sight Diagnostics Parasight platform, which provides malaria diagnosis, species identification, and parasite quantification. We conducted a multisite trial in Chennai, India (Apollo Hospital [n = 205]), and Nairobi, Kenya (Aga Khan University Hospital [n = 263]), in which we compared the device to microscopy, RDTs, and PCR. For identification of malaria, the device performed similarly well in both contexts (sensitivity of 99% and specificity of 100% at the Indian site and sensitivity of 99.3% and specificity of 98.9% at the Kenyan site, compared to PCR). For species identification, the device correctly identified 100% of samples with Plasmodium vivax and 100% of samples with Plasmodium falciparum in India and 100% of samples with P. vivax and 96.1% of samples with P. falciparum in Kenya, compared to PCR. Lastly, comparisons of the device parasite counts with those of trained microscopists produced average Pearson correlation coefficients of 0.84 at the Indian site and 0.85 at the Kenyan site.

Same but different? A qualitative analysis of the influence of COVID-19 on law enforcement and organized crime in Germany.

Criminological research on COVID-19 and its repercussions on crimes, criminals and law enforcement agencies is still in its infancy. This paper fills that void with regard to the influence of COVID-19 on organized crime and the work of law enforcement agencies' investigations of organized crime in Germany by presenting empirical findings from a nationwide qualitative interview study. Through the methodological combination of Grounded Theory and Situational Analysis, we find three central narratives (us vs. them, nationalization vs. internationalization, conservatism vs. innovation) that were provided by law enforcement personnel in terms of the way in which COVID-19 influenced both organized crime groups and their work in the investigation thereof. Following a reflexive approach, the implications of COVID-19 on the research process itself are also discussed.

The brain-immune cells axis controls tissue specific immunopathology.

During viral infections, cell death can be induced as a direct result of cytopathic virus replication in various cell types and tissues or as an immune response of the host to the infectious agent. This leads to an infiltration of inflammatory cells, causing subsequent tissue damage. The balance between effective elimination of the pathogen and prevention of fatal tissue damage is decisive for life. The host has developed various mechanisms to inhibit excessive immune responses.