A Semiquantitative Scoring System for Histopathological and Immunohistochemical Assessment of Lesions and Tissue Tropism in Avian Influenza

Landmann, Maria; Scheibner, David; Graaf, Annika; Gischke, Marcel; Koethe, Susanne; Fatola, Olanrewaju I.; Raddatz, Barbara B.; Mettenleiter, Thomas C.; Beer, Martin; Grund, Christian; Harder, Timm C.; Mostafa, Ahmed; Ulrich, Reiner

doi:10.3390/v13050868

Cited by 27 publications

(30 citation statements)

References 72 publications

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“…The tissues were examined under a light microscope (Axiolab, Zeiss, Jena, Germany) for evaluation of histopathological lesions in the H&E-stained sections and the detection of the immuno labelling of the viral antigen in the IHC-stained ones. For an assessment of histopathological lesions, the semiquantitative scoring system proposed by Landnann et al [ 22 ] was applied.…”

Section: Methodsmentioning

confidence: 99%

Homo- and Heterosubtypic Immunity to Low Pathogenic Avian Influenza Virus Mitigates the Clinical Outcome of Infection with Highly Pathogenic Avian Influenza H5N8 Clade 2.3.4.4.b in Captive Mallards (Anas platyrhynchos)

et al. 2023

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In this study, we investigated the clinical response, viral shedding, transmissibility, pathologic lesions, and tropism of HPAIV Gs/Gd H5N8 subtype (clade 2.3.4.4b), following experimental infection of three groups of captive mallards (Anas platyrhynchos): (i) fully susceptible, (ii) pre-exposed to low pathogenic avian influenza virus (LPAIV) H5N1 subtype, and (iii) pre-exposed to LPAIV H3N8 subtype. Infection of naïve mallards with HPAIV H5N8 resulted in ~60% mortality, neurological signs, abundant shedding, and transmission to contact ducks, who also became sick and died. High amounts of viral RNA were found in all collected organs, with the highest RNA load recorded in the brain. The IHC examinations performed on tissues collected at 4 and 14 days post-infection (dpi) revealed tropism to nervous tissue, myocardium, respiratory epithelium, and hepatic and pancreatic cells. The mallards pre-exposed to LPAIV H5N1 and challenged with HPAIV H5N8 were asymptomatic and showed a significant reduction of viral RNA shedding, yet still sufficient to cause infection (but no disease) in the contact ducks. The AIV antigen was not detected in organs at 4 and 14 dpi, and microscopic lesions were mild and scarce. Similarly, mallards previously inoculated with LPAIV H3N8 remained healthy after challenge with HPAIV H5N8, but viral RNA was detected in large quantities in swabs and organs, particularly in the early phase of infection. However, in contrast to mallards from group I, the IHC staining yielded negative results at the selected timepoints. The virus was transmitted to contact birds, which remained symptomless but demonstrated low levels of viral RNA shedding and mild- to moderate tissue damage despite negative IHC staining. The results indicate that naïve mallards are highly susceptible to HPAIV H5N8 clade 2.3.4.4b and that homo- and heterosubtypic immunity to LPAIV can mitigate the clinical outcomes of infection.

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Section: Methodsmentioning

confidence: 99%

Homo- and Heterosubtypic Immunity to Low Pathogenic Avian Influenza Virus Mitigates the Clinical Outcome of Infection with Highly Pathogenic Avian Influenza H5N8 Clade 2.3.4.4.b in Captive Mallards (Anas platyrhynchos)

et al. 2023

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“…Finally, tissue sections were counterstained with hematoxylin and examined microscopically. Recently proposed semiquantitative scoring system for lesions assessment was then applied [ 28 ].…”

Section: Methodsmentioning

confidence: 99%

Pathogenicity of highly pathogenic avian influenza H5N8 subtype for herring gulls (Larus argentatus): impact of homo- and heterosubtypic immunity on the outcome of infection

Tarasiuk

Kycko

Knitter

et al. 2022

Vet Res

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To improve understanding of the pathobiology of highly pathogenic avian influenza virus (HPAIV) infections in wild birds, pathogenicity and transmissibility of HPAIV H5N8 subtype clade 2.3.4.4b was evaluated in ~ 8-week-old herring gulls (Larus argentatus) divided into 3 groups: naïve birds (group A), birds previously exposed to low pathogenic avian influenza virus (LPAIV) H5N1 (group B) and LPAIV H13N6 (group C). The HPAIV H5N8 virus was highly virulent for naïve gulls, that showed early morbidity, high mortality, a broad spectrum of clinical signs, including violent neurological disorders, systemic distribution of the virus in organs accompanied by high level of shedding and transmission to contact birds. Pre-exposure to homologous and heterologous LPAIV subtypes conferred only partial protection: we observed increased survival rate (statistically significant only in group B), nervous signs, pantropic distribution of virus in organs, shedding (significantly reduced in gulls of group C in the early phase of disease and asymptomatic shedding in the late phase), transmission to contact gulls (more pronounced in group B) and near-complete seroconversion in survivors. Histopathological and immunohistochemical results indicate virus tropism for the neural, respiratory and myocardial tissues. In conclusion, we demonstrate that HPAIV H5N8 clade 2.3.4.4b is highly virulent and lethal for fully susceptible herring gulls and that pre-exposure to homo- and heterosubtypic LPAIV only partially modulates the disease outcome.

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“…For histopathological examination, half of each trachea, lung, intestine, pancreas, spleen, bursa, and kidney was fixed in 10% neutral buffered formalin and processed by paraffin embedding techniques [ 24 ]. The scoring of histopathology was accomplished according to Landmann et al, 2021 [ 25 ]. Briefly, each organ was collected from birds in each group at 2, 4, and 7 dpi.…”

Section: Methodsmentioning

confidence: 99%

Genetic Variations among Different Variants of G1-like Avian Influenza H9N2 Viruses and Their Pathogenicity in Chickens

Adel

Abdelmagid

Mohamed

et al. 2022

Viruses

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Since it was first discovered, the low pathogenic avian influenza (LPAI) H9N2 subtype has established linages infecting the poultry population globally and has become one of the most prevalent influenza subtypes in domestic poultry. Several different variants and genotypes of LPAI H9N2 viruses have been reported in Egypt, but little is known about their pathogenicity and how they have evolved. In this study, four different Egyptian LPAI H9N2 viruses were genetically and antigenically characterized and compared to representative H9N2 viruses from G1 lineage. Furthermore, the pathogenicity of three genetically distinct Egyptian LPAI H9N2 viruses was assessed by experimental infection in chickens. Whole-genome sequencing revealed that the H9N2 virus of the Egy-2 G1-B lineage (pigeon-like) has become the dominant circulating H9N2 genotype in Egypt since 2016. Considerable variation in virus shedding at day 7 post-infections was detected in infected chickens, but no significant difference in pathogenicity was found between the infected groups. The rapid spread and emergence of new genotypes of the influenza viruses pinpoint the importance of continuous surveillance for the detection of novel reassortant viruses, as well as monitoring the viral evolution.

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A Semiquantitative Scoring System for Histopathological and Immunohistochemical Assessment of Lesions and Tissue Tropism in Avian Influenza

Cited by 27 publications

References 72 publications

Homo- and Heterosubtypic Immunity to Low Pathogenic Avian Influenza Virus Mitigates the Clinical Outcome of Infection with Highly Pathogenic Avian Influenza H5N8 Clade 2.3.4.4.b in Captive Mallards (Anas platyrhynchos)

Homo- and Heterosubtypic Immunity to Low Pathogenic Avian Influenza Virus Mitigates the Clinical Outcome of Infection with Highly Pathogenic Avian Influenza H5N8 Clade 2.3.4.4.b in Captive Mallards (Anas platyrhynchos)

Pathogenicity of highly pathogenic avian influenza H5N8 subtype for herring gulls (Larus argentatus): impact of homo- and heterosubtypic immunity on the outcome of infection

Genetic Variations among Different Variants of G1-like Avian Influenza H9N2 Viruses and Their Pathogenicity in Chickens

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