Bats belong to the order Chiroptera that represents the second largest order of mammals with more than 1200 species and an almost global distribution. Environmental changes and deforestation have severely influenced many ecosystems, intensifying the contact between wildlife and humans. In recent years, bats have been found to harbor a number of different viruses with zoonotic potential, as well as a great diversity of astroviruses, for which the question of zoonotic potential remains unanswered to date. Human astroviruses have been identified as the causative agent for diarrhea in children and immunocompromised patients. For a long time, astroviruses have been considered to be strictly species-specific. However, a great genetic diversity has recently been discovered among animal and human astroviruses that might indicate the potential of these viruses to cross species barriers. Furthermore, our knowledge about the tissue tropism of astroviruses has been expanded to some neurotropic strains that have recently been shown to be responsible for encephalitis in humans and livestock. This review gives an overview on what is known about astroviruses in bats, humans and livestock, especially bovines and pigs. Future research activities are suggested to unravel astrovirus infection dynamics in bat populations to further assess the zoonotic potential of these viruses.

Influenza during pregnancy can affect the health of offspring in later life, among which neurocognitive disorders are among the best described. Here, we investigate whether maternal influenza infection has adverse effects on immune responses in offspring. We establish a two-hit mouse model to study the effect of maternal influenza A virus infection (first hit) on vulnerability of offspring to heterologous infections (second hit) in later life. Offspring born to influenza A virus infected mothers are stunted in growth and more vulnerable to heterologous infections (influenza B virus and MRSA) than those born to PBS- or poly(I:C)-treated mothers. Enhanced vulnerability to infection in neonates is associated with reduced haematopoetic development and immune responses. In particular, alveolar macrophages of offspring exposed to maternal influenza have reduced capacity to clear second hit pathogens. This impaired pathogen clearance is partially reversed by adoptive transfer of alveolar macrophages from healthy offspring born to uninfected dams. These findings suggest that maternal influenza infection may impair immune ontogeny and increase susceptibility to early life infections of offspring.

Hendra virus (HeV) and Nipah virus (NiV) belong to the genus Henipavirus in the family Paramyxoviridae. Henipavirus infections were first reported in the 1990’s causing severe and often fatal outbreaks in domestic animals and humans in Southeast Asia and Australia. NiV infections were observed in humans in Bangladesh, India and in the first outbreak in Malaysia, where pigs were also infected. HeV infections occurred in horses in the North-Eastern regions of Australia, with singular transmission events to humans. Bats of the genus Pteropus have been identified as the reservoir hosts for henipaviruses. Molecular and serological indications for the presence of henipa-like viruses in African fruit bats, pigs and humans have been published recently. In our study, truncated forms of HeV and NiV attachment (G) proteins as well as the full-length NiV nucleocapsid (N) protein were expressed using different expression systems. Based on these recombinant proteins, Enzyme-linked Immunosorbent Assays (ELISA) were developed for the detection of HeV or NiV specific antibodies in porcine serum samples. We used the NiV N ELISA for initial serum screening considering the general reactivity against henipaviruses. The G protein based ELISAs enabled the differentiation between HeV and NiV infections, since as expected, the sera displayed higher reactivity with the respective homologous antigens. In the future, these assays will present valuable tools for serosurveillance of swine and possibly other livestock or wildlife species in affected areas. Such studies will help assessing the potential risk for human and animal health worldwide by elucidating the distribution of henipaviruses.

The trichomycterid catfish species Trichomycterus alternatus (Eigenmann, 1917) and Trichomycterus zonatus (Eigenmann, 1918) are reportedly among the most pervasive species in mid- to high-elevation coastal streams of Southeastern Brazil. Despite their apparent abundance and ecological ubiquity, the applicability of their names is still uncertain. Examination of the type material of the two species reveals that part of the confusion stems from a mixing of species in the T. zonatus type series. Other issues relate to reports of character conditions in the respective species that do not actually correspond to the situation in their type specimens. Such situation triggered a long-lasting chain of taxonomic misinterpretations and erroneous identification protocols and traditions so that even the taxonomic distinctiveness of the two species is nebulous. That situation is disentangled in detail on the basis of new information on the holotypes and remaining type specimens of each species by classical and new (stereo triplet radiography) morphology analyses for data acquisition. Results show that the type specimens of T. alternatus and T. zonatus differ pronouncedly in several traits of internal and external morphology and represent markedly distinct taxa. The latter species does not correspond to most identifications in the literature and is, in fact, endemic to the region of its type locality. We also clarify and map the reported localities of the type material and offer comments on the validity of T. alternatus and T. zonatus, along with that of possibly related forms.

SARS-CoV-2 infection is associated with increased morbidities in men compared to women. Androgens are believed to play an important role in SARS-CoV-2 pathogenesis in men due to the postulated androgen-dependency of ACE2 and TMPRSS2. However, it is yet unclear whether the sex bias is mediated by SARS-CoV-2 infection itself or by other confounding factors. Here, using the golden hamster model, we show that SARS-CoV-2 infection attacks reproductive organs, causes massive dysregulation of sex hormones and induces elevated transcription of the androgen-to-estrogen converting enzyme aromatase CYP19A1 in the lung. In male hamsters, SARS-CoV-2 infection causes severely depleted testosterone and highly elevated estradiol levels. In female hamsters, SARS-CoV-2 infection causes reduced estradiol levels. Hormonal dysregulation in infected animals is followed by severe weight loss compared to control groups treated with poly(I:C) or PBS. Lungs of SARS-CoV-2 infected animals present abundant CYP19A1 expression in the endothelium and in macrophages, particularly in males. Prominent CYP19A1 expression in endothelial cells and macrophages was verified in lung sections of deceased Covid-19 males compared to females. Our results demonstrate that SARS-CoV-2 infection leads to massive dysregulation of sex hormones, which may increase the risk for sex-specific disease outcome particularly in combination with comorbidities. These findings provide insights into the complex metabolic cross talk between SARS-CoV-2 infection and sex hormones.