Journal of Microbiology

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Crystal structures of the μ2 subunit of clathrin-adaptor protein 2 in complex with peptides derived from human papillomavirus 16 E7: Sujin Jung, Dahwan Lim, Joon Sig Choi, Ho-Chul Shin, Seung Jun Kim, Bonsu Ku; J. Microbiol. 2025;63(8):e2505003. Published online August 31, 2025; DOI: https://doi.org/10.71150/jm.2505003

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Abstract PDF: Human papillomaviruses (HPVs) cause abnormal cellular proliferation, leading to malignant or benign lesions, such as cervical cancer and warts. The genome of HPV16, the most prevalent high-risk oncogenic genotype within the Alphapapillomavirus genus, encodes two oncoproteins. One of these proteins, E7, interacts with multiple host proteins and modulates their functions through distinct pathways. The CR2 domain of HPV16 E7 was recently reported to interact with the μ2 subunit of clathrin-adaptor protein 2 (AP2-μ2), an adaptor complex involved in cargo internalization during clathrin-mediated endocytosis. In this study, to provide molecular insights into their intermolecular interactions, we determined the crystal structures of AP2-μ2 in complex with the HPV16 E7-derived peptides. Subsequent biochemical analyses revealed that this interaction is primarily maintained by the Y-x-x-Φ motif and further supported by acidic cluster residues of HPV16 E7. Finally, sequence alignment of the E7 CR2 domains from various HPV genotypes showed that the AP2-μ2-binding motif is largely conserved in Alpha-, Beta-, and Mupapillomaviruses, but not in Nu- and Gammapapillomaviruses.

Mouse strain-dependent neutralizing antibody responses to Zika virus vaccines: Sang Hwan Seo, Jung-ah Choi, Eunji Yang, Hayan Park, Dae-Im Jung, Jae-Ouk Kim, Jae Seung Yang, Manki Song; J. Microbiol. 2025;63(8):e2504005. Published online August 31, 2025; DOI: https://doi.org/10.71150/jm.2504005

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Abstract PDF: The 2015 Zika virus (ZIKV) outbreak in Brazil and its global spread underscored the urgent need for effective and broadly protective vaccines. While C57BL/6 and BALB/c mice are widely used in preclinical vaccine research, direct comparisons of their ability to elicit ZIKV-specific neutralizing antibodies (nAbs) remain limited. This study aimed to systematically evaluate and compare the immunogenic potential of these two common mouse strains across diverse vaccine platforms, focusing on their capacity to generate functional neutralizing antibody responses. We assessed nAb and IgG responses following four vaccination strategies: (1) DNA vaccine encoding prMEΔTM followed by E protein domain III boost, (2) recombinant EΔTM protein expressed using baculovirus system, (3) formalin-inactivated ZIKV, and (4) live ZIKV. Although both strains generated detectable ZIKV- and E protein-specific IgG, the magnitude and quality of responses varied by vaccine platform and strain. Notably, C57BL/6 mice consistently mounted significantly higher nAb titers than BALB/c mice across all immunization groups, including subunit- and whole-virus-based vaccines. In contrast, BALB/c mice showed lower or undetectable nAb responses, despite comparable or higher total IgG levels in some cases. These findings show that host genetic background is a critical determinant of vaccine-induced neutralization and underscore the importance of selecting appropriate animal models in ZIKV vaccine development. C57BL/6 mice, due to their robust nAb responses, represent a reliable model for evaluating vaccine immunogenicity. Conversely, the limited nAb responses in BALB/c mice position them as a potential low-responder model, offering a stringent system to test the potency and breadth of protective immunity under suboptimal conditions.

Efficient CRISPR-based genome editing for inducible degron systems to enable temporal control of protein function in large double-stranded DNA virus genomes: Kihye Shin, Eui Tae Kim; J. Microbiol. 2025;63(9):e2504008. Published online August 29, 2025; DOI: https://doi.org/10.71150/jm.2504008

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Abstract PDF: CRISPR-Cas9-based gene editing enables precise genetic modifications. However, its application to human cytomegalovirus (HCMV) remains challenging due to the large size of the viral genome and the essential roles of key regulatory genes. Here, we establish an optimized CRISPR-Cas9 system for precise labeling and functional analysis of HCMV immediate early (IE) genes. By integrating a multifunctional cassette encoding an auxin-inducible degron (AID), a self-cleaving peptide (P2A), and GFP into the viral genome via homology-directed repair (HDR), we achieved efficient knock-ins without reliance on bacterial artificial chromosome (BAC) cloning, a labor-intensive and time-consuming approach. We optimized delivery strategies, donor template designs, and component ratios to enhance HDR efficiency, significantly improving knock-in success rates. This system enables real-time fluorescent tracking and inducible protein degradation, allowing temporal control of essential viral proteins through auxin-mediated depletion. Our approach provides a powerful tool for dissecting the dynamic roles of viral proteins throughout the HCMV life cycle, facilitating a deeper understanding of viral pathogenesis and potential therapeutic targets.

Efficient and modular reverse genetics system for rapid generation of recombinant severe acute respiratory syndrome coronavirus 2: Sojung Bae, Jinjong Myoung; J. Microbiol. 2025;63(7):e2504015. Published online July 21, 2025; DOI: https://doi.org/10.71150/jm.2504015

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Abstract PDF: The global spread of COVID-19 has underscored the urgent need for advanced tools to study emerging coronaviruses. Reverse genetics systems have become indispensable for dissecting viral gene functions, developing live-attenuated vaccine candidates, and identifying antiviral targets. In this study, we describe a robust and efficient reverse genetics platform for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The system is based on the assembly of a full-length infectious cDNA clone from seven overlapping fragments, each flanked by homologous sequences to facilitate seamless assembly using the Gibson assembly method. Individual cloning of each fragment into plasmids enables modular manipulation of the viral genome, allowing rapid site-directed mutagenesis by fragment exchange. Infectious recombinant virus was successfully recovered from the assembled cDNA, exhibiting uniform plaque morphology and genetic homogeneity compared to clinical isolates. Additionally, fluorescent reporter viruses were generated to enable real-time visualization of infection, and the effects of different mammalian promoters on viral rescue were evaluated. This reverse genetics platform enables efficient generation and manipulation of recombinant SARS-CoV-2, providing a valuable resource for virological research and the development of preventive and therapeutic antiviral measures.

Inhibiting kinesin family member 20A disrupts Zika virus entry by blocking internalization: Jeonghyeon Lee, Younghyun Lim, Hyeong-Rae Kim, Yong-Bin Cho, In-Gu Lee, Young-Jin Seo; J. Microbiol. 2025;63(6):e2503008. Published online June 30, 2025; DOI: https://doi.org/10.71150/jm.2503008

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Abstract PDF Supplementary Material: Zika virus, a mosquito-borne virus, is associated with congenital birth defects and neurological complications. However, despite its significant public health threat, no approved vaccines or antiviral treatments are currently available. Therefore, this study aims to identify kinesin family member 20A as a key host factor promoting Zika virus life cycle. The elevated expression of kinesin family member 20A following Zika virus infection suggests its role in the viral life cycle. Suppressing its expression through gene silencing or inhibiting its function with a small-molecule inhibitor significantly reduced viral infectivity in host cells. Furthermore, kinesin family member 20A is essential for facilitating viral internalization, a key step in the entry step. These findings suggest its significance in the Zika virus life cycle and highlight its potential as a novel therapeutic target for the Zika virus.

Antiviral effects of heme oxygenase-1 against canine coronavirus and canine influenza virus in vitro: Jae-Hyeong Kim, Dong-Hwi Kim, Kyu-Beom Lim, Joong-Bok Lee, Seung-Yong Park, Chang-Seon Song, Sang-Won Lee, Dong-Hun Lee, Do-Geun Kim, Hun-Young Yoon, In-Soo Choi; J. Microbiol. 2025;63(5):e2501029. Published online May 27, 2025; DOI: https://doi.org/10.71150/jm.2501029

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Abstract PDF Supplementary Material: Heme oxygenase-1 (HO-1) has antioxidant, anti-apoptotic, and anti-inflammatory properties. Emerging evidence shows that HO-1 also exhibits antiviral activity against severe acute respiratory syndrome coronavirus 2, human immunodeficiency virus, hepatitis B virus, and Ebola virus. Its antiviral effects are mediated not only by its enzymatic function but also through the modulation of interferon-related pathways, thereby inhibiting viral replication. In this study, we investigated the antiviral effects of HO-1 on canine coronavirus (CCoV) and canine influenza virus (CIV) H3N2 using cell-based assays. To determine whether HO-1 suppresses CCoV and CIV, cells were treated with hemin to induce HO-1 expression. Hemin treatment successfully induced HO-1 expression in A72 and Madin-Darby canine kidney cells, resulting in the suppression of CCoV and CIV replication. The canine HO-1 gene was cloned into an expression vector and transfected into cells to achieve transient overexpression. Recombinant canine HO-1 protein was expressed in Escherichia coli and purified using an expression vector. HO-1 overexpression suppressed CCoV and CIV replication in cells. Following viral infection, treatment with purified HO-1 protein led to a reduction in viral protein levels. Therefore, both HO-1 expression and exogenous protein treatment effectively inhibited CCoV and CIV replication. Elevated HO-1 protein levels consistently reduced viral RNA and protein expression in vitro. These findings suggest that HO-1 could serve as a potential therapeutic agent for managing viral infections in dogs.

The key pathways and genes related to oncolytic Newcastle disease virus-induced phenotypic changes in ovarian cancer cells: Wei Song, Yuan Yuan, Fangfang Cao, Huazheng Pan, Yaqing Liu; J. Microbiol. 2025;63(4):e2411018. Published online April 29, 2025; DOI: https://doi.org/10.71150/jm.2411018

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Abstract PDF Supplementary Material

The poor prognosis and high recurrence rate of ovarian cancer highlight the urgent need to develop new therapeutic strategies. Oncolytic Newcastle disease virus (NDV) can kill cancer cells directly and regulate innate and adaptive immunity. In this study, ovarian cancer cells infected with or without velogenic NDV-BJ were subjected to a CCK-8 assay for detecting cell proliferation, flow cytometry for detecting the cell cycle and apoptosis, and wound healing and transwell assays for detecting cell migration and invasion. Transcriptomic sequencing was conducted to identify the differentially expressed genes (DEGs). GO and KEGG enrichment analyses were performed to explore the mechanism underlying the oncolytic effect of NDV on ovarian cancer cells. The results showed that infection with NDV inhibited ovarian cancer cell proliferation, migration, and invasion; disrupted the cell cycle; and promoted apoptosis. Compared with those in negative control cells, the numbers of upregulated and downregulated genes in ovarian cancer cells infected with NDV were 1,499 and 2,260, respectively. Thirteen KEGG pathways related to cell growth and death, cell mobility, and signal transduction were significantly enriched. Among these pathways, 48 DEGs, especially SESN2, HLA B/C/E, GADD45B, and RELA, that may be involved in the oncolytic process were screened, and qPCR analysis verified the reliability of the transcription data. This study discovered some key pathways and genes related to oncolytic NDV-induced phenotypic changes in ovarian cancer cells, which will guide our future research directions and help further explore the specific mechanisms by which infection with NDV suppresses ovarian cancer development.

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Newcastle Disease Virus Vaccine Strain H as a Potential Oncolytic Agent in Ovarian Cancer Therapy
V. A. Sarkisova, S. Sh. Karshieva, A. A Makarova, D. O. Neymysheva, P. M. Chumakov
Molecular Biology.2025; 59(6): 1055. CrossRef

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Advancements in dengue vaccines: A historical overview and pro-spects for following next-generation candidates: Kai Yan, Lingjing Mao, Jiaming Lan, Zhongdang Xiao; J. Microbiol. 2025;63(2):e2410018. Published online February 27, 2025; DOI: https://doi.org/10.71150/jm.2410018

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