Antibodies against H1N1 influenza virus cross-react with α-cells of pancreatic islets

The heterophilicic epitopes in conserved HA regions of human and avian influenza viruses can produce antibodies that bound to kidney tissue

Influenza virus infection can cause kidney damage. However, the link between influenza infection and disease is still unclear. The purpose of this study was to analyze the relationship between heterophilic epitopes on H5N1 hemagglutinin (HA) and disease. The monoclonal antibody (mAb) against H5N1 was prepared, mAbs binding to human kidney tissue were screened, and the reactivities of mAbs with five different subtypes of influenza virus were detected. Design and synthesize the peptides according to the common amino acid sequence of these antigens, and analyze the distribution of the epitope on the crystal structure of HA. Immunological methods were used to detect whether the heterophilic epitopes could induce the production of antibodies that cross-react with kidney tissue. The results showed that H5-30 mA b binding to human kidney tissue recognized the heterophilic epitope 191-LVLWGIHHP-199 on the head of HA. The key amino acid were V192, L193, W194 and I196, which were highly conserved in human and avian influenza virus HA. The heterophilic epitope could induce mice to produce different mAbs binding to kidney tissue. Such heterophilic antibodies were also detected in the serum of the patients. It can provide materials for the mechanism of renal diseases caused by influenza virus infection.

The distribution of heterophilic antigens and their relationship with autoimmune diseases

Introduction

Microbial infections are associated with the occurrence of autoimmune diseases, but the mechanisms of microbial infection inducing autoimmune diseases are not fully understood. The existence of heterophilic antigens between microorganisms and human tissues may explain part of the pathogenesis of autoimmune diseases. Here, we investigate the distribution of heterophilic antigens and its relationship with autoimmune diseases.

Methods

Monoclonal antibodies against a variety of microorganisms were prepared. The titer, subclass and reactivity of antibodies with microorganisms were identified, and heterophilic antibodies that cross-reacted with human tissues were screened by human tissue microarray. The reactivity of these heterophilic antibodies with different individuals and different species was further examined by immunohistochemistry.

Results

In this study, 21 strains of heterophilic antibodies were screened. The results showed that these heterophilic antibodies were produced due to the existence of heterophilic antigens between microorganism and human body and the distribution of heterophilic antigens had individual, tissue and species differences.

Conclusion

Our study showed that heterophilic antigens exist widely between microorganisms and human body, and the heterophilic antigens carried by microorganisms may break the immune tolerance of the body through carrier effect and initiate immune response, which may be one of the important mechanisms of infection inducing autoimmune diseases.

Diabetogenic viruses: linking viruses to diabetes mellitus

Diabetes Mellitus (DM) is a group of chronic metabolic diseases distinguished by elevated glycemia due to the alterations in insulin metabolism. DM is one of the most relevant diseases of the modern world, with high incidence and prevalence worldwide, associated with severe systemic complications and increased morbidity and mortality rates. Although genetic factors and lifestyle habits are two of the main factors involved in DM onset, viral infections, such as enteroviruses, cytomegalovirus, hepatitis C virus, human immunodeficiency virus, severe acute respiratory syndrome coronavirus 2, among others, have been linked as triggers of type 1 (T1DM) and type 2 (T2DM) diabetes. Over the years, various groups identified different mechanisms as to how viruses can promote these metabolic syndromes. However, this field is still poorly explored and needs further research, as millions of people live with these pathologies. Thus, this review aims to ex-plore the different processes of how viruses can induce DM and their contribution to the prevalence and incidence of DM worldwide.

Characterization of Influenza A and B Viruses Circulating in Southern China During the 2017-2018 Season

The trivalent seasonal influenza vaccine was the only approved and available vaccine during the 2016–2018 influenza seasons. It did not include the B/Yamagata strain. In this study, we report an acute respiratory disease outbreak associated with influenza B/Yamagata infections in Guangzhou, Southern China (January through March, 2018). Among the 9914 patients, 2241 (22.6%) were positive for the influenza B virus, with only 312 (3.1%) positive for the influenza A virus. The influenza B/Yamagata lineage dominated during this period in Southern China. The highest incidence of influenza A virus infection occurred in the children aged 5–14 years. In contrast, populations across all age groups were susceptible to the influenza B virus. Phylogenetic, mutations, and 3D structure analyses of hemagglutinin (HA) genes were performed to assess the vaccine-virus relatedness. The recommended A/H1N1 vaccine strain (A/Michigan/45/2015) during both 2017–2018 and 2018–2019 was antigen-specific for these circulating isolates (clade 6B.1) in Spring 2018. An outbreak of influenza B/Yamagata (clade 3) infections in 2018 occurred during the absence of the corresponding vaccine during 2016–2018. The recommended influenza B/Yamagata vaccine strain (B/Phuket/3073/2013) for the following season (2018–2019) was antigen-specific. Although there were only a few influenza B/Victoria infections in Spring 2018, five amino acid mutations were identified in the HA antigenic sites of the 19 B/Victoria isolates (clade 1A), when compared with the 2016–2018 B/Victoria vaccine strain. The number was larger than expected and suggested that the influenza B HA gene may be more variable than previously thought. One of the mutations (K180N) was noted to likely alter the epitope and to potentially affect the viral antigenicity. Seven mutations were also identified in the HA antigenic sites of 2018–2020 B/Victoria vaccine strain, of which some or all may reduce immunogenicity and the protective efficacy of the vaccine, perhaps leading to more outbreaks in subsequent seasons. The combined epidemiological, phylogenetic, mutations, and 3D structural analyses of the HA genes of influenza strains reported here contribute to the understanding and evaluation of how HA mutations affect vaccine efficacy, as well as to providing important data for screening and selecting more specific, appropriate, and effective influenza vaccine candidate strains.

Comparative review of respiratory diseases caused by coronaviruses and influenza A viruses during epidemic season

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to sweep the world, causing infection of millions and death of hundreds of thousands. The respiratory disease that it caused, COVID-19 (stands for coronavirus disease in 2019), has similar clinical symptoms with other two CoV diseases, severe acute respiratory syndrome and Middle East respiratory syndrome (SARS and MERS), of which causative viruses are SARS-CoV and MERS-CoV, respectively. These three CoVs resulting diseases also share many clinical symptoms with other respiratory diseases caused by influenza A viruses (IAVs). Since both CoVs and IAVs are general pathogens responsible for seasonal cold, in the next few months, during the changing of seasons, clinicians and public heath may have to distinguish COVID-19 pneumonia from other kinds of viral pneumonia. This is a discussion and comparison of the virus structures, transmission characteristics, clinical symptoms, diagnosis, pathological changes, treatment and prevention of the two kinds of viruses, CoVs and IAVs. It hopes to provide information for practitioners in the medical field during the epidemic season.

Pandemic influenza and subsequent risk of type 1 diabetes: a nationwide cohort study

AIMS/HYPOTHESIS

Case reports have linked influenza infections to the development of type 1 diabetes. We investigated whether pandemic and seasonal influenza infections were associated with subsequent increased risk of type 1 diabetes.

METHODS

In this population-based registry study, we linked individual-level data from national health registries for the entire Norwegian population under the age of 30 years for the years 2006-2014 (2.5 million individuals). Data were obtained from the National Registry (population data), the Norwegian Patient Registry (data on inpatient and outpatient specialist care), the Primary Care Database, the Norwegian Prescription Database and the Norwegian Surveillance System for Communicable Diseases. Pandemic influenza was defined as either a clinical influenza diagnosis during the main pandemic period or a laboratory-confirmed test. Seasonal influenza was defined by a clinical diagnosis of influenza between 2006 and 2014. We used Cox regression to estimate HRs for new-onset type 1 diabetes after an influenza infection, adjusted for year of birth, sex, place of birth and education.

RESULTS

The adjusted HR for type 1 diabetes after pandemic influenza infection was 1.19 (95% CI 0.97, 1.46). In the subgroup with laboratory-confirmed influenza A (H1N1), influenza was associated with a twofold higher risk of subsequent type 1 diabetes before age 30 years (adjusted HR: 2.26, 95% CI 1.51, 3.38).

CONCLUSIONS/INTERPRETATION

Overall, we could not demonstrate a clear association between clinically reported pandemic influenza infection and incident type 1 diabetes. However, we found a twofold excess of incident diabetes in the subgroup with laboratory-confirmed pandemic influenza A (H1N1).

Respiratory virus-induced heterologous immunity: Part of the problem or part of the solution?

Purpose

To provide current knowledge on respiratory virus-induced heterologous immunity (HI) with a focus on humoral and cellular cross-reactivity. Adaptive heterologous immune responses have broad implications on infection, autoimmunity, allergy and transplant immunology. A better understanding of the mechanisms involved might ultimately open up possibilities for disease prevention, for example by vaccination.

Methods

A structured literature search was performed using Medline and PubMed to provide an overview of the current knowledge on respiratory-virus induced adaptive HI.

Results

In HI the immune response towards one antigen results in an alteration of the immune response towards a second antigen. We provide an overview of respiratory virus-induced HI, including viruses such as respiratory syncytial virus (RSV), rhinovirus (RV), coronavirus (CoV) and influenza virus (IV). We discuss T cell receptor (TCR) and humoral cross-reactivity as mechanisms of HI involving those respiratory viruses. Topics covered include HI between respiratory viruses as well as between respiratory viruses and other pathogens. Newly developed vaccines, which have the potential to provide protection against multiple virus strains are also discussed. Furthermore, respiratory viruses have been implicated in the development of autoimmune diseases, such as narcolepsy, Guillain-Barré syndrome, type 1 diabetes or myocarditis. Finally, we discuss the role of respiratory viruses in asthma and the hygiene hypothesis, and review our recent findings on HI between IV and allergens, which leads to protection from experimental asthma.

Conclusion

Respiratory-virus induced HI may have protective but also detrimental effects on the host. Respiratory viral infections contribute to asthma or autoimmune disease development, but on the other hand, a lack of microbial encounter is associated with an increasing number of allergic as well as autoimmune diseases. Future research might help identify the elements which determine a protective or detrimental outcome in HI-based mechanisms.

Respiratory virus-induced heterologous immunity: Part of the problem or part of the solution?

Purpose

To provide current knowledge on respiratory virus-induced heterologous immunity (HI) with a focus on humoral and cellular cross-reactivity. Adaptive heterologous immune responses have broad implications on infection, autoimmunity, allergy and transplant immunology. A better understanding of the mechanisms involved might ultimately open up possibilities for disease prevention, for example by vaccination.

Methods

A structured literature search was performed using Medline and PubMed to provide an overview of the current knowledge on respiratory-virus induced adaptive HI.

Results

In HI the immune response towards one antigen results in an alteration of the immune response towards a second antigen. We provide an overview of respiratory virus-induced HI, including viruses such as respiratory syncytial virus (RSV), rhinovirus (RV), coronavirus (CoV) and influenza virus (IV). We discuss T cell receptor (TCR) and humoral cross-reactivity as mechanisms of HI involving those respiratory viruses. Topics covered include HI between respiratory viruses as well as between respiratory viruses and other pathogens. Newly developed vaccines which have the potential to provide protection against multiple virus strains are also discussed. Furthermore, respiratory viruses have been implicated in the development of autoimmune diseases, such as narcolepsy, Guillain–Barré syndrome, type 1 diabetes or myocarditis. Finally, we discuss the role of respiratory viruses in asthma and the hygiene hypothesis, and review our recent findings on HI between IV and allergens, which leads to protection from experimental asthma.

Conclusion

Respiratory-virus induced HI may have protective but also detrimental effects on the host. Respiratory viral infections contribute to asthma or autoimmune disease development, but on the other hand, a lack of microbial encounter is associated with an increasing number of allergic as well as autoimmune diseases. Future research might help identify the elements which determine a protective or detrimental outcome in HI-based mechanisms.