Sex disparities in influenza: A multiscale network analysis

Transmission of a human isolate of clade 2.3.4.4b A(H5N1) virus in ferrets

Since 2020, there has been unprecedented global spread of highly pathogenic avian influenza A(H5N1) in wild bird populations with spillover into a variety of mammalian species and sporadically humans1. In March 2024, clade 2.3.4.4b A(H5N1) virus was first detected in dairy cattle in the USA, with subsequent detection in numerous states2, leading to more than a dozen confirmed human cases3,4. In this study, we used the ferret, a well-characterized animal model that permits concurrent investigation of viral pathogenicity and transmissibility5, in the evaluation of A/Texas/37/2024 (TX/37) A(H5N1) virus isolated from a dairy farm worker in Texas6. Here we show that the virus has a remarkable ability for robust systemic infection in ferrets, leading to high levels of virus shedding and spread to naive contacts. Ferrets inoculated with TX/37 rapidly exhibited a severe and fatal infection, characterized by viraemia and extrapulmonary spread. The virus efficiently transmitted in a direct contact setting and was capable of indirect transmission through fomites. Airborne transmission was corroborated by the detection of infectious virus shed into the air by infected animals, albeit at lower levels compared to those of the highly transmissible human seasonal and swine-origin H1 subtype strains. Our results show that despite maintaining an avian-like receptor-binding specificity, TX/37 exhibits heightened virulence, transmissibility and airborne shedding relative to other clade 2.3.4.4b virus isolated before the 2024 cattle outbreaks7, underscoring the need for continued public health vigilance.

Characterization of H5N1 avian influenza virus isolated from bird in Russia with the E627K mutation in the PB2 protein

Currently A(H5Nx) avian influenza viruses are globally widespread and continue to evolve. Since their emergence in 2020 novel highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b reassortant viruses have become predominant in the world and caused multiple infections in mammals. It was shown that some of A(H5N1) viruses mostly isolated from mammals contain an E627K mutation in the PB2 protein which can lead to adaptation of influenza viruses to mammalian cells. In 2023 in Russia we have isolated two highly pathogenic avian influenza A(H5N1) clade 2.3.4.4b viruses from birds one of which contained an E627K mutation in the PB2 protein. This virus had increased virulence in mice. Limited airborne transmission of the virus with the PB2-E627K mutation was observed between ferrets, in which infectious virus was detected in the nasal washings of the three of the twelve recipient ferrets, and clinical symptoms of the disease were observed in one case. Both viruses showed dominant binding to avian-type sialoside receptors, which was most likely the reason for the limited transmissibility. Thus, this study indicates a possible limited increase in the pandemic potential of A(H5N1) 2.3.4.4b viruses and highlights the importance of continuous avian influenza surveillance for pandemic preparedness and response.

Modulation of endoplasmic reticulum stress response pathways by respiratory viruses

Acute respiratory infections (ARIs) are amongst the leading causes of death and disability, and the greatest burden of disease impacts children, pregnant women, and the elderly. Respiratory viruses account for the majority of ARIs. The unfolded protein response (UPR) is a host homeostatic defence mechanism primarily activated in response to aberrant endoplasmic reticulum (ER) resident protein accumulation in cell stresses including viral infection. The UPR has been implicated in the pathogenesis of several respiratory diseases, as the respiratory system is particularly vulnerable to chronic and acute activation of the ER stress response pathway. Many respiratory viruses therefore employ strategies to modulate the UPR during infection, with varying effects on the host and the pathogens. Here, we review the specific means by which respiratory viruses affect the host UPR, particularly in association with the high production of viral glycoproteins, and the impact of UPR activation and subversion on viral replication and disease pathogenesis. We further review the activation of UPR in common co-morbidities of ARIs and discuss the therapeutic potential of modulating the UPR in virally induced respiratory diseases.

An aggregated dataset of serial morbidity and titer measurements from influenza A virus-infected ferrets

Data from influenza A virus (IAV) infected ferrets provides invaluable information towards the study of novel and emerging viruses that pose a threat to human health. This gold standard model can recapitulate many clinical signs of infection present in IAV-infected humans, support virus replication of human, avian, swine, and other zoonotic strains without prior adaptation, and permit evaluation of virus transmissibility by multiple modes. While ferrets have been employed in risk assessment settings for >20 years, results from this work are typically reported in discrete stand-alone publications, making aggregation of raw data from this work over time nearly impossible. Here, we describe a dataset of 728 ferrets inoculated with 126 unique IAV, conducted by a single research group under a uniform experimental protocol. This collection of morbidity, mortality, and viral titer data represents the largest publicly available dataset to date of in vivo-generated IAV infection outcomes on a per-ferret level.

Sex- and species-associated differences in complement-mediated immunity in humans and rhesus macaques

The complement system can be viewed as a "moderator" of innate immunity, "instructor" of humoral immunity, and "regulator" of adaptive immunity. While sex is known to affect humoral and cellular immune systems, its impact on complement in humans and rhesus macaques, a commonly used non-human primate model system, has not been well studied. To address this knowledge gap, we analyzed serum samples from 90 humans and 72 rhesus macaques for the abundance and activity of the complement system components. While sequences of cascade proteins were highly conserved, dramatically different levels were observed between species. Whereas the low levels detected in rhesus samples raised questions about the suitability of the test for use with macaque samples, differences in levels of complement proteins were observed in male and female humans. Levels of total and antibody-dependent deposition of C1q and C3b on a glycosylated antigen differed between humans and rhesus, suggesting differential recognition of glycans and balance between classical and alternative activation pathways. Functional differences in complement-mediated lysis of antibody-sensitized cells were observed in multiple assays and showed that human females frequently exhibited higher lytic activity than human males or rhesus macaques, which typically did not exhibit such sex-associated differences. Other differences between species and sexes were observed in more narrow contexts-for only certain antibodies, antigens, or assays. Collectively, these results expand knowledge of sex-associated differences in the complement system in humans, identifying differences absent from rhesus macaques.IMPORTANCEThe complement system is a critical part of host defense to many bacterial, fungal, and viral infections. In parallel, rich epidemiological, clinical, and biomedical research evidence demonstrates that sex is an important biological variable in immunity, and many sex-specific differences in immune system are intimately tied with disease outcomes. This study focuses on the intersection of these two factors to define the impact of sex on complement pathway components and activities. This work expands our knowledge of sex-associated differences in the complement system in humans and also identifies the differences that appear to be absent in rhesus macaques, a popular non-human primate model. Whereas differences between species suggest potential limitations in the ability of macaque model to recapitulate human biology, knowledge of sex-based differences in humans has the potential to inform clinical research and practice.

Sex and species associated differences in Complement-mediated immunity in Humans and Rhesus macaques

The complement system can be viewed as a 'moderator' of innate immunity, 'instructor' of humoral immunity, and 'regulator' of adaptive immunity. While sex and aging are known to affect humoral and cellular immune systems, their impact on the complement pathway in humans and rhesus macaques, a commonly used non-human primate model system, have not been well-studied. To address this knowledge gap, we analyzed serum samples from 90 humans and 75 rhesus macaques for the abundance and activity of the complement system components. While sequences of cascade proteins were highly conserved, dramatically different levels were observed between species. Whereas the low levels detected in rhesus samples raised questions about the suitability of the test, differences in levels of complement proteins were observed in male and female humans. Levels of total and antibody-dependent deposition of C1q and C3b on a glycosylated antigen differed between human and rhesus, suggesting differential recognition of glycans. Functional differences in complement-mediated lysis of antibody-sensitized cells were observed in multiple assays and showed that human females frequently exhibited higher lytic activity than human males or rhesus macaques, which typically did not exhibit such sexual dimorphism. Other differences between species and sexes were observed in more narrow contexts-for only certain antibodies, antigens, or assays. Collectively, these results expand our knowledge of sexual dimorphism in the complement system in humans, identifying differences that appear to be absent from rhesus macaques.

Disease parameters following ocular herpes simplex virus type 1 infection are similar in male and female BALB/C mice

Sex related differences in the incidence or severity of infection have been described for multiple viruses. With herpes simplex viruses, the best example is HSV-2 genital infection where women have a higher incidence of infection and can have more severe infections than men. HSV-1 causes several types of infections including skin and mucosal ulcers, keratitis, and encephalitis in humans that do not appear to have a strong biological sex component. Given that mouse strains differ in their MHC loci it is important to determine if sex differences occur in multiple strains of mice. Our goal was to answer two questions: Are virus related sex differences present in BALB/C mice and does virulence of the viral strain have an effect? We generated a panel of recombinant HSV-1 viruses with differing virulence phenotypes and characterized multiple clinical correlates of ocular infection in BALB/c mice. We found no sex-specific differences in blepharitis, corneal clouding, neurovirulence, and viral titers in eye washes. Sex differences in neovascularization, weight loss and eyewash titers were observed for some recombinants, but these were not consistent across the phenotypes tested for any recombinant virus. Considering these findings, we conclude that there are no significant sex specific ocular pathologies in the parameters measured, regardless of the virulence phenotype following ocular infection in BALB/c mice, suggesting that the use of both sexes is not necessary for the bulk of ocular infection studies.

Sex-biased expression of the TLR7 gene in severe COVID-19 patients: Insights from transcriptomics and epigenomics

There is abundant epidemiological data indicating that the incidence of severe cases of coronavirus disease (COVID-19) is significantly higher in males than females worldwide. Moreover, genetic variation at the X-chromosome linked TLR7 gene has been associated with COVID-19 severity. It has been suggested that the sex-biased incidence of COVID-19 might be related to the fact that TLR7 escapes X-chromosome inactivation during early embryogenesis in females, thus encoding a doble dose of its gene product compared to males. We analyzed TLR7 expression in two acute phase cohorts of COVID-19 patients that used two different technological platforms, one of them in a multi-tissue context including saliva, nasal, and blood samples, and a third cohort that included different post-infection timepoints of long-COVID-19 patients. We additionally explored methylation patterns of TLR7 using epigenomic data from an independent cohort of COVID-19 patients stratified by severity and sex. In line with genome-wide association studies, we provide supportive evidence indicating that TLR7 has altered CpG methylation patterns and it is consistently downregulated in males compared to females in the most severe cases of COVID-19.

iMS2Net: A multiscale networking methodology to decipher metabolic synergy of organism

The metabolic responses of organism to external stimuli are characterized by the multicellular- and multiorgan-based synergistic regulation. Network analysis is a powerful tool to investigate this multiscale interaction. The imaging mass spectrometry (iMS)-based spatial omics provides multidimensional and multiscale information, thus offering the possibility of network analysis to investigate metabolic response of organism to environmental stimuli. We present iMS dataset-sourced multiscale network (iMS2Net) strategy to uncover prenatal environmental pollutant (PM2.5)-induced metabolic responses in the scales of cell and organ from metabolite abundances and metabolite-metabolite interaction using mouse fetal model, including metabotypic similarity, metabolic vulnerability, metabolic co-variability and metabolic diversity within and between organs. Furthermore, network-based analysis results confirm close associations between lipid metabolites and inflammatory cytokine release. This networking methodology elicits particular advantages for modeling the dynamic and adaptive processes of organism under environmental stresses or pathophysiology and provides molecular mechanism to guide the occurrence and development of systemic diseases.