91桃色

Immunohistochemistry; Infectious diseases; Tissue diagnostics; pathogen detection; Nucleic acid probes; Antigen detection; Histopathology; Molecular pathology; Formalin-fixed paraffin-embedded tissues

Introduction

Accurate and timely detection of infectious agents within tissue samples is critical for effective diagnosis and management of infectious diseases [1]. Two cornerstone techniques in situ hybridization (ISH) and immunohistochemistry (IHC) have emerged as powerful tools in the diagnostic pathology arsenal, offering both sensitivity and spatial resolution. ISH enables the direct localization of pathogen-specific nucleic acids within tissue sections using labeled complementary probes, while IHC detects pathogen-associated proteins or host immune markers through specific antigen-antibody interactions. Together, these techniques bridge the gap between traditional histopathology and modern molecular diagnostics. They not only confirm the presence of pathogens but also provide contextual insight into tissue architecture, inflammation, and host response [2]. Their applicability across a wide range of infectious agents including viruses, bacteria, fungi, and parasites makes them invaluable in cases where culture methods are insufficient or infeasible, such as in formalin-fixed, paraffin-embedded (FFPE) tissues or when dealing with fastidious organisms. As infectious disease challenges evolve with emerging pathogens and increasing immunosuppressed populations, ISH and IHC continue to play an essential role in diagnostic precision. Their integration into routine practice not only enhances diagnostic accuracy but also supports personalized treatment strategies and deeper understanding of host-pathogen dynamics at the tissue level [3].

Discussion

The application of in situ hybridization (ISH) and immunohistochemistry (IHC) in infectious disease diagnostics represents a significant advancement in the visualization and identification of pathogens within tissue specimens. Unlike conventional culture-based methods or PCR, which often lack spatial context, ISH and IHC allow clinicians and pathologists to detect infectious agents in situ within their native tissue environments while preserving crucial morphological and architectural details [4]. ISH has become increasingly valuable for detecting viral and bacterial nucleic acids directly within tissue sections. The specificity of nucleic acid probes permits the differentiation of closely related organisms, a capability that is particularly useful in distinguishing between similar viral strains or identifying co-infections. This technique has proven instrumental in identifying human papillomavirus (HPV) in cervical tissues, Epstein-Barr virus (EBV) in lymphomas, and Mycobacterium tuberculosis in granulomatous inflammation when culture results are inconclusive or delayed [5].

IHC, on the other hand, enables the detection of pathogen-derived proteins and host immune responses. Its relatively straightforward workflow and compatibility with FFPE samples have made it a routine diagnostic tool. IHC is frequently used to identify fungal elements in invasive infections, cytomegalovirus (CMV) antigens in transplant recipients, and viral antigens in encephalitis cases [6]. Furthermore, dual-staining approaches combining IHC with cell-type markers offer insights into the cell tropism and pathogenesis of the infectious agent. The combined use of ISH and IHC provides a complementary diagnostic strategy. ISH confirms the presence of genetic material, whereas IHC highlights protein expression, enabling correlation of pathogen replication with host immune activation. This dual approach strengthens diagnostic confidence, particularly in complex or chronic infections [7].

Despite their strengths, these techniques are not without limitations. ISH can be technically demanding and time-consuming, requiring optimized probe design and signal amplification systems. IHC, while more accessible, may sometimes suffer from cross-reactivity or limited availability of high-quality antibodies [8]. Both methods rely heavily on the quality of tissue preservation and the expertise of the interpreting pathologist. With the advent of automated staining platforms and multiplexed assays, the diagnostic capabilities of ISH and IHC are rapidly evolving. Newer platforms now allow for simultaneous detection of multiple pathogens and host biomarkers in a single tissue section, offering more comprehensive diagnostic insights [9]. The integration of digital pathology and artificial intelligence further enhances the potential of these methods by enabling standardized, reproducible interpretation and quantification. In summary, ISH and IHC remain indispensable tools in infectious disease pathology. Their ability to detect and localize pathogens in the histological context of tissue inflammation and damage offers a unique advantage in diagnostic precision. As molecular techniques continue to evolve, the future of tissue-based infectious disease diagnostics will likely involve the convergence of ISH, IHC, and other omics-based methods to deliver highly sensitive, specific, and spatially resolved diagnostic data [10].

Conclusion

In situ hybridization (ISH) and immunohistochemistry (IHC) have established themselves as vital components in the diagnostic evaluation of infectious diseases. Their ability to detect and localize pathogens directly within tissue contexts provides a unique advantage over conventional diagnostic methods, especially in complex or atypical clinical presentations. By preserving tissue architecture while identifying nucleic acids or protein markers, these techniques offer both sensitivity and spatial resolution enhancing diagnostic accuracy and guiding clinical decision-making. As the landscape of infectious diseases continues to shift with the emergence of novel pathogens and growing immunocompromised populations, the need for reliable, tissue-based diagnostics becomes even more critical. The ongoing refinement of ISH and IHC technologies coupled with advancements in automation, multiplexing, and digital pathology promises to further expand their utility in both routine diagnostics and research. Ultimately, the integration of ISH and IHC into comprehensive diagnostic strategies supports the goals of precision medicine by enabling tailored treatment approaches and deeper understanding of host-pathogen interactions. As we continue to bridge traditional histopathology with modern molecular tools, these techniques will remain at the forefront of infectious disease diagnostics, ensuring timely, targeted, and effective patient care.

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