1
|
Sakai Y, Mura S, Kuwabara Y, Kagimoto S, Sakurai M, Morimoto M, Park ES, Shimojima M, Nagata N, Ami Y, Yoshikawa T, Iwata-Yoshikawa N, Fukushi S, Watanabe S, Kurosu T, Okutani A, Kimura M, Imaoka K, Saijo M, Morikawa S, Suzuki T, Maeda K. Lethal severe fever with thrombocytopenia syndrome virus infection causes systemic germinal centre failure and massive T cell apoptosis in cats. Front Microbiol 2024; 14:1333946. [PMID: 38249467 PMCID: PMC10796997 DOI: 10.3389/fmicb.2023.1333946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 12/19/2023] [Indexed: 01/23/2024] Open
Abstract
Introduction Severe fever with thrombocytopenia syndrome (SFTS) is a fatal viral disease characterized by high fever, thrombocytopenia, leukopenia, and multi-organ haemorrhage. Disruption of the humoral immune response and decreased lymphocyte numbers are thought to contribute to the disease severity. These findings have been obtained through the analysis of peripheral blood leukocytes in human patients, whereas analysis of lymph nodes has been limited. Thus, in this study, we characterized the germinal centre response and apoptosis in the lymph nodes of cats with fatal SFTS, because SFTS in cats well mimics the pathology of human SFTS. Methods Lymph node tissue sections collected during necropsy from seven fatal SFTS patients and five non-SFTS cases were used for histopathological analysis. Additionally, lymph node tissue sections collected from cats with experimental infection of SFTS virus (SFTSV) were also analysed. Results In the lymphoid follicles of cats with SFTS, a drastic decrease in Bcl6- and Ki67-positive germinal centre B cells was observed. Together, the number of T cells in the follicles was also decreased in SFTS cases. In the paracortex, a marked increase in cleaved-caspase3 positivity was observed in T cells. These changes were independent of the number of local SFTS virus-positive cell. Furthermore, the analysis of cats with experimental SFTSV infection revealed that the intrafollicular Bcl6- and CD3-positive cell numbers in cats with low anti-SFTSV antibody production were significantly lower than those in cats with high anti-SFTSV antibody production. Discussion These results suggest that dysfunction of the humoral response in severe SFTS was caused by the loss of germinal centre formation and massive apoptosis of T cells in the lymph nodes due to systemically circulating viruses.
Collapse
Affiliation(s)
- Yusuke Sakai
- Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Serina Mura
- Laboratory of Veterinary Pathology, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Yuko Kuwabara
- Laboratory of Veterinary Pathology, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Saya Kagimoto
- Laboratory of Veterinary Pathology, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Masashi Sakurai
- Laboratory of Veterinary Pathology, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Masahiro Morimoto
- Laboratory of Veterinary Pathology, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Eun-sil Park
- Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan
| | - Masayuki Shimojima
- Department of Virology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Noriyo Nagata
- Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Yasushi Ami
- Management Department of Biosafety and Laboratory Animal, National Institute of Infectious Diseases, Tokyo, Japan
| | - Tomoki Yoshikawa
- Department of Virology I, National Institute of Infectious Diseases, Tokyo, Japan
| | | | - Shuetsu Fukushi
- Department of Virology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Shumpei Watanabe
- Faculty of Veterinary Medicine, Okayama University of Science, Ehime, Japan
| | - Takeshi Kurosu
- Department of Virology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Akiko Okutani
- Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan
| | - Masanobu Kimura
- Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan
| | - Koichi Imaoka
- Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan
| | - Masayuki Saijo
- Department of Virology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Shigeru Morikawa
- Faculty of Veterinary Medicine, Okayama University of Science, Ehime, Japan
| | - Tadaki Suzuki
- Department of Pathology, National Institute of Infectious Diseases, Tokyo, Japan
| | - Ken Maeda
- Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan
| |
Collapse
|
2
|
Abstract
Pathogens vary in their antigenic complexity. While some pathogens such as measles present a few relatively invariant targets to the immune system, others such as malaria display considerable antigenic diversity. How the immune response copes in the presence of multiple antigens, and whether a trade-off exists between the breadth and efficacy of antibody (Ab)-mediated immune responses, are unsolved problems. We present a theoretical model of affinity maturation of B-cell receptors (BCRs) during a primary infection and examine how variation in the number of accessible antigenic sites alters the Ab repertoire. Naive B cells with randomly generated receptor sequences initiate the germinal centre (GC) reaction. The binding affinity of a BCR to an antigen is quantified via a genotype-phenotype map, based on a random energy landscape, that combines local and distant interactions between residues. In the presence of numerous antigens or epitopes, B-cell clones with different specificities compete for stimulation during rounds of mutation within GCs. We find that the availability of many epitopes reduces the affinity and relative breadth of the Ab repertoire. Despite the stochasticity of somatic hypermutation, patterns of immunodominance are strongly shaped by chance selection of naive B cells with specificities for particular epitopes. Our model provides a mechanistic basis for the diversity of Ab repertoires and the evolutionary advantage of antigenically complex pathogens.
Collapse
Affiliation(s)
- Lauren M Childs
- Center for Communicable Disease Dynamics, Harvard T.H. Chan School of Public Health, Boston, MA, USA Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | | | - Sarah Cobey
- Ecology and Evolution, University of Chicago, Chicago, IL, USA
| |
Collapse
|