Bovine aortic endothelial cells are susceptible to hantavirus infection; a new aspect in hantavirus ecology

Biodefense Implications of New-World Hantaviruses

Hantaviruses, part of the Bunyaviridae family, are a genus of negative-sense, single-stranded RNA viruses that cause two major diseases: New-World Hantavirus Cardiopulmonary Syndrome and Old-World Hemorrhagic Fever with Renal Syndrome. Hantaviruses generally are found worldwide with each disease corresponding to their respective hemispheres. New-World Hantaviruses spread by specific rodent-host reservoirs and are categorized as emerging viruses that pose a threat to global health and security due to their high mortality rate and ease of transmission. Incidentally, reports of Hantavirus categorization as a bioweapon are often contradicted as both US National Institute of Allergy and Infectious Diseases and the Centers for Disease Control and Prevention refer to them as Category A and C bioagents respectively, each retaining qualitative levels of importance and severity. Concerns of Hantavirus being engineered into a novel bioagent has been thwarted by Hantaviruses being difficult to culture, isolate, and purify limiting its ability to be weaponized. However, the natural properties of Hantaviruses pose a threat that can be exploited by conventional and unconventional forces. This review seeks to clarify the categorization of Hantaviruses as a bioweapon, whilst defining the practicality of employing New-World Hantaviruses and their effect on armies, infrastructure, and civilian targets.

Performance assessment of the SAPS II and SOFA scoring systems in Hanta virus Hemorrhagic Fever with Renal Syndrome

BACKGROUND

Hemorrhagic Fever with Renal Syndrome (HFRS), caused by the hantavirus, is a natural infectious disease characterized by fever, hemorrhage and renal damage. China is the most severely endemic area for HFRS in the world. In recent years, critical scoring systems based on quantitative classification have become an important clinical tool for predicting and evaluating the prognosis of critical illness, and provide guidelines for clinical practice.

METHODS

The sample comprised 384 patients with HFRS treated in the Taizhou Hospital from January 2006 to February 2017. The patients were divided into the severe group and the mild group according to their clinical characteristics. By comparing the differences in clinical symptoms, signs and laboratory data between the two groups, the clinically relevant indicators of severe HFRS were explored. According to the previous studies, we incorporated the positive fecal occult blood test (FOBT) into the sepsis-related organ failure assessment (SOFA) tool and formulated a new scoring system specifically for HFRS, named H-SOFA. By comparing the simplified acute physiology score II (SAPS II), SOFA and H-SOFA scores of the two groups, their predictive values for the progression of HFRS were assessed.

RESULTS

Compared to the mild group, patients in the severe group had longer hospital stays; higher frequencies of nausea, vomiting, abdomen pain, signs of congestion and hemorrhage; and more pronounced impairment of liver and renal function. The levels of PLT, PCT, TB, and FOBT were positively correlated with the progression of HFRS (P<0.001). Patients with HFRS in the severe group got significantly higher scores on the SAPS II, SOFA, and H-SOFA scoring systems (P<0.001). The values of SAPS II, SOFA and H-SOFA, were significantly correlated with the severity of HFRS, and the AUC values were 0.90, 0.96, and 0.98, respectively.

CONCLUSION

PLT, PCT, TB, and FOBT were independent predictors of severe HFRS; SAPS II, SOFA, and H-SOFA had high predictive value for the progression of severe HFRS, with H-SOFA being the highest.

Factors predicting kidney damage in Puumala virus infected patients in Southern Denmark

In Europe, infections with Puumala hantavirus cause nephropathia epidemica. Presently the risk factors predicting severe kidney damage after Puumala virus infection are not well known. The objective of the study was to investigate environmental and individual factors predicting severe kidney damage caused by serologically established Puumala infections. In a nationwide cohort study we investigated all serologically established Puumala infections in Southern Denmark from 1996 to 2012. A total of 184 patients had serologically verified Puumala virus infection. In patients with Puumala virus infections the decrease of platelet counts preceded acute kidney failure. Multivariable logistic regression demonstrated that recent activities in the forest, platelet counts, and flu-like symptoms predicted estimated glomerular filtration rates less than 30 mL/min/1.73 m(²), but not age, gender, fever, nor abdominal pain. Severe kidney damage in Puumala infections in Southern Denmark is associated with the risk of recent activities in the forest.

A new permanent cell line derived from the bank vole (Myodes glareolus) as cell culture model for zoonotic viruses

Background

Approximately 60% of emerging viruses are of zoonotic origin, with three-fourths derived from wild animals. Many of these zoonotic diseases are transmitted by rodents with important information about their reservoir dynamics and pathogenesis missing. One main reason for the gap in our knowledge is the lack of adequate cell culture systems as models for the investigation of rodent-borne (robo) viruses in vitro. Therefore we established and characterized a new cell line, BVK168, using the kidney of a bank vole, Myodes glareolus, the most abundant member of the Arvicolinae trapped in Germany.

Results

BVK168 proved to be of epithelial morphology expressing tight junctions as well as adherence junction proteins. The BVK168 cells were analyzed for their infectability by several arbo- and robo-viruses: Vesicular stomatitis virus, vaccinia virus, cowpox virus, Sindbis virus, Pixuna virus, Usutu virus, Inkoo virus, Puumalavirus, and Borna disease virus (BDV). The cell line was susceptible for all tested viruses, and most interestingly also for the difficult to propagate BDV.

Conclusion

In conclusion, the newly established cell line from wildlife rodents seems to be an excellent tool for the isolation and characterization of new rodent-associated viruses and may be used as in vitro-model to study properties and pathogenesis of these agents.

Hantavirus causing hemorrhagic fever with renal syndrome enters from the apical surface and requires decay-accelerating factor (DAF/CD55)

The Old World hantaviruses, members of the family Bunyaviridae, cause hemorrhagic fever with renal syndrome (HFRS). Transmission to humans occurs via inhalation of aerosols contaminated with the excreta of infected rodents. The viral antigen is detectable in dendritic cells, macrophages, lymphocytes, and, most importantly, microvascular endothelial cells. However, the site and detailed mechanism of entry of HFRS-causing hantaviruses in polarized epithelial cells have not yet been defined. Therefore, this study focused on the entry of the pathogenic hantaviruses Hantaan and Puumala into African green monkey kidney epithelial cells and primary human endothelial cells. The polarized epithelial and endothelial cells were found to be susceptible to hantavirus infection exclusively from the apical surface. Treatment with phosphatidylinositol-specific phospholipase C, which removes glycosylphosphatidylinositol (GPI)-anchored proteins from the cell surface, protects cells from infection, indicating that hantaviruses require a GPI-anchored protein as a cofactor for entry. Decay-accelerating factor (DAF)/CD55 is a GPI-anchored protein of the complement regulatory system and serves as a receptor for attachment to the apical cell surface for a number of viruses. Infection was reduced by the pretreatment of hantaviral particles with human recombinant DAF. Moreover, the treatment of permissive cells with DAF-specific antibody blocked infection. These results demonstrate that the Old World hantaviruses Hantaan and Puumala enter polarized target cells from the apical site and that DAF is a critical cofactor for infection.

Testing the Possibility to Protect Bovine PrPC Transgenic Swiss Mice Against Bovine PrPSc Infection by DNA Vaccination Using Recombinant Plasmid Vectors Harboring and Expressing the Complete or Partial cDNA Sequences of Bovine PrPc

The objective of this study was to investigate the molecular mechanisms of neurobiological processes involved in the degeneration of the central nervous system. The bovine spongiform encephalopathy (BSE) was used as experimental model system for investigation of transmissible spongiform encephalopathy (TSE). The experimental strategy was to evaluate the possibility for protection of bovine PrP(C) transgenic mice against a bovine PrP(Sc) infection by DNA vaccination using the complete or partial cDNA sequences of the bovine prion protein. Three recombinant plasmids pCR3.1-EX-PrP-BSE-C20 (C20), pCR3.1-EX-PrP-BSE-90-235-C4 (C4), and pCR3.1-EX-PrP-BSE-106-131-C14 (C14) were constructed. These mammalian expression vectors harbor complete (C20) or partial (C4 and C14) cDNA sequences of the Bos taurus PrP(C) (BTPrP(C)) encoding for amino acid residues 1-264 (C20), 90-235 (C4), and 106-131 (C14) of the BTPrP(C). Transgenic mice harboring and expressing BTPrP(C) were generated using the donor strain C57/CBA, receptor strain Swiss mouse, and recombinant plasmid MoPrPXho-boPrP. Crossing of positive transgenic mice to bovine PrP and negative to murine PrP with 129/OLA (murine PrP-/-) and C57BL6x129/OLA (murine PrP+/-) mice was carried out to amplify the colony of transgenic mice termed bovine PrP(C) transgenic Swiss mice (BTPrP-TgM). The capabilities of C20, C4, and C14 to express the corresponding cDNA sequence of BTPrP(C) in vitro and in vivo were confirmed prior to DNA vaccination of the BTPrP-TgM using NIH 3T3 cells and BALB/c mice, respectively. In order to prove the capability of the constructed expression vectors to protect BTPrP-TgM in vivo against a BSE infection 80 female BTPrP-TgM were vaccinated intramuscularly and subcutaneously with DNA of the plasmids C20, C4, C14, and parental vector pCR3.1 (100 microg DNA corresponding to about 26-30 pmol DNA/animal and application) in four groups (each consists of 20 animals). DNA vaccination was followed by three additional boosters. The vaccinated animals (15 animals of each group) were challenged twice per oral with homogenates of brain material obtained from BSE cattle containing the infectious PrP(Sc) (100 microl/animal which corresponds to 15 mg of a 15% brain homogenate). The first and second challenge experiments were performed 76-83 and 181 days post DNA vaccination, respectively. A part of the vaccinated animals (3-5 animals of each group) that served as internal negative control were mock infected using the brain homogenate of healthy cattle or Phosphate saline buffer (PBS). A variety of symptoms and clinical pictures were observed during the monitoring of DNA vaccinated animals. However, the observed diseases seem to be similar in all experimental animal groups. After an observation period of 14 months post the second challenge experiment the remaining animals (some animals died or were sacrificed when moribund during the study) were sacrificed after expiration of the experimental schedule. The right hemisphere of the brain and a half of the spleen tissue of the individual animals were used for detection of PrP(Sc) by Western blot analysis. The misfolded bovine PrP(Sc) was not detected in the brain or spleen tissues of those animals that were vaccinated with DNA of C20, which was able to express the complete bovine PrP(C) protein in vitro and in vivo. In contrast, the bovine PrP(Sc) was detected in the brain or spleen tissues of animals that were DNA vaccinated with DNA of the parental vector pCR3.1, with DNA of C4, or with DNA of C14. The results of these studies underline that the constructed expression vector C20 possesses the protective capacity to inhibit the formation of misfolded bovine PrP(Sc) in BTPrP-TgM under the conditions used. A delay of occurrence of TSE-specific symptoms in the majority of the vaccinated animals seems to be due to the prolonged incubation time of BSE infection.

New Ecological Aspects of Hantavirus Infection: A Change of A Paradigm and a Challenge of Prevention- A Review

In the last decades a significant number of so far unknown or underestimated pathogens have emerged as fundamental health hazards of the human population despite intensive research and exceptional efforts of modern medicine to embank and eradicate infectious diseases. Almost all incidents caused by such emerging pathogens could be ascribed to agents that are zoonotic or expanded their host range and crossed species barriers. Many different factors influence the status of a pathogen to remain unnoticed or evolves into a worldwide threat. The ability of an infectious agent to adapt to changing environmental conditions and variations in human behavior, population development, nutrition, education, social, and health status are relevant factors affecting the correlation between pathogen and host. Hantaviruses belong to the emerging pathogens having gained more and more attention in the last decades. These viruses are members of the family Bunyaviridae and are grouped into a separate genus known as Hantavirus. The serotypes Hantaan (HTN), Seoul (SEO), Puumala (PUU), and Dobrava (DOB) virus predominantly cause hemorrhagic fever with renal syndrome (HFRS), a disease characterized by renal failure, hemorrhages, and shock. In the recent past, many hantavirus isolates have been identified and classified in hitherto unaffected geographic regions in the New World (North, Middle, and South America) with characteristic features affecting the lungs of infected individuals and causing an acute pulmonary syndrome. Hantavirus outbreaks in the United States of America at the beginning of the 10th decade of the last century fundamentally changed our knowledge about the appearance of the hantavirus specific clinical picture, mortality, origin, and transmission route in human beings. The hantavirus pulmonary syndrome (HPS) was first recognized in 1993 in the Four Corners Region of the United States and had a lethality of more than 50%. Although the causative virus was first termed in connection with the geographic name of its outbreak region the analysis of the individual viruses indicate that the causing virus of HPS was a genetically distinct hantavirus and consequently termed as Sin Nombre virus. Hantaviruses are distributed worldwide and are assumed to share a long time period of co-evolution with specific rodent species as their natural reservoir. The degree of relatedness between virus serotypes normally coincides with the relatedness between their respective hosts. There are no known diseases that are associated with hantavirus infections in rodents underlining the amicable relationship between virus and host developed by mutual interaction in hundreds of thousands of years. Although rodents are the major reservoir, antibodies against hantaviruses are also present in domestic and wild animals like cats, dogs, pigs, cattle, and deer. Domestic animals and rodents live jointly in a similar habitat. Therefore the transmission of hantaviruses from rodents to domestic animals seems to be possible, if the target organs, tissues, and cell parenchyma of the co-habitat domestic animals possess adequate virus receptors and are suitable for hantavirus entry and replication. The most likely incidental infection of species other than rodents as for example humans turns hantaviruses from harmless to life-threatening pathogenic agents focusing the attention on this virus group, their ecology and evolution in order to prevent the human population from a serious health risk. Much more studies on the influence of non-natural hosts on the ecology of hantaviruses are needed to understand the directions that the hantavirus evolution could pursue. At least, domestic animals that share their environmental habitat with rodents and humans particularly in areas known as high endemic hantavirus regions have to be copiously screened. Each transfer of hantaviruses from their original natural hosts to other often incidental hosts is accompanied by a change of ecology, a change of environment, a modulation of numerous factors probably influencing the pathogenicity and virulence of the virus. The new environment exerts a modified evolutionary pressure on the virus forcing it to adapt and probably to adopt a form that is much more dangerous for other host species compared to the original one.

Bovine aortic endothelial cells are susceptible to Hantaan virus infection

Hantavirus serotype Hantaan (HTN) is one of the causative agents of hemorrhagic fever with renal syndrome (HFRS, lethality up to 10%). The natural host of HTN is Apodemus agrarius. Recent studies have shown that domestic animals like cattle are sporadically seropositive for hantaviruses. In the present study, the susceptibility of bovine aortic endothelial cells (BAEC) expressing alpha(V)beta(3)-integrin to a HTN infection was investigated. Viral nucleocapsid protein and genomic RNA segments were detected in infected BAEC by indirect immunofluorescence assay, Western blot analysis, and reverse transcription-polymerase chain reaction (RT-PCR), respectively. The results of this study strongly support our previous observation on Puumala virus (PUU) that has been propagated efficiently in BAEC. These findings open a new window to contemplate the ecology of hantavirus infection and transmission route from animal to man.