Spatiotemporally Orchestrated Interactions between Viral and Cellular Proteins Involved in the Entry of African Swine Fever Virus

African swine fever (ASF) is a highly contagious hemorrhagic disease in domestic pigs and wild boars with a mortality of up to 100%. The causative agent, African swine fever virus (ASFV), is a member of the Asfarviridae family of the nucleocytoplasmic large DNA viruses. The genome size of ASFV ranges from 170 to 194 kb, encoding more than 50 structural and 100 nonstructural proteins. ASFV virions are 260–300 nm in diameter and composed of complex multilayered structures, leading to an intricate internalization pathway to enter host cells. Currently, no commercial vaccines or antivirals are available, due to the insufficient knowledge of the viral receptor(s), the molecular events of ASFV entry into host cells, and the functions of virulence-associated genes. During the early stage of ASFV infection, the fundamental aspects of virus-host interactions, including virus internalization, intracellular transport through the endolysosomal system, and membrane fusion with endosome, are precisely regulated and orchestrated via a series of molecular events. In this review, we summarize the currently available knowledge on the pathways of ASFV entry into host cells and the functions of viral proteins involved in virus entry. Furthermore, we conclude with future perspectives and highlight areas that require further investigation. This review is expected to provide unique insights for further understanding ASFV entry and facilitate the development of vaccines and antivirals.

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Induction of Robust Immune Responses in Swine by Using a Cocktail of Adenovirus-Vectored African Swine Fever Virus Antigens

Clinical and Vaccine Immunology ◽

10.1128/cvi.00395-16 ◽

2016 ◽

Vol 23 (11) ◽

pp. 888-900 ◽

Cited By ~ 17

Author(s):

Shehnaz Lokhandwala ◽

Suryakant D. Waghela ◽

Jocelyn Bray ◽

Cameron L. Martin ◽

Neha Sangewar ◽

...

Keyword(s):

Immune Responses ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus ◽

Host Cells ◽

Hemorrhagic Disease ◽

Virulent Strains ◽

Challenge Study ◽

Cellular Immune

ABSTRACTThe African swine fever virus (ASFV) causes a fatal hemorrhagic disease in domestic swine, and at present no treatment or vaccine is available. Natural and gene-deleted, live attenuated strains protect against closely related virulent strains; however, they are yet to be deployed and evaluated in the field to rule out chronic persistence and a potential for reversion to virulence. Previous studies suggest that antibodies play a role in protection, but induction of cytotoxic T lymphocytes (CTLs) could be the key to complete protection. Hence, generation of an efficacious subunit vaccine depends on identification of CTL targets along with a suitable delivery method that will elicit effector CTLs capable of eliminating ASFV-infected host cells and confer long-term protection. To this end, we evaluated the safety and immunogenicity of an adenovirus-vectored ASFV (Ad-ASFV) multiantigen cocktail formulated in two different adjuvants and at two immunizing doses in swine. Immunization with the cocktail rapidly induced unprecedented ASFV antigen-specific antibody and cellular immune responses against all of the antigens. The robust antibody responses underwent rapid isotype switching within 1 week postpriming, steadily increased over a 2-month period, and underwent rapid recall upon boost. Importantly, the primed antibodies strongly recognized the parental ASFV (Georgia 2007/1) by indirect fluorescence antibody (IFA) assay and Western blotting. Significant antigen-specific gamma interferon-positive (IFN-γ+) responses were detected postpriming and postboosting. Furthermore, this study is the first to demonstrate induction of ASFV antigen-specific CTL responses in commercial swine using Ad-ASFV multiantigens. The relevance of the induced immune responses in regard to protection needs to be evaluated in a challenge study.

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An immortalized porcine macrophage cell line competent for the isolation of African swine fever virus

Scientific Reports ◽

10.1038/s41598-021-84237-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kentaro Masujin ◽

Tomoya Kitamura ◽

Ken -ichiro Kameyama ◽

Kota Okadera ◽

Tatsuya Nishi ◽

...

Keyword(s):

Viral Replication ◽

Cell Line ◽

Genetic Manipulation ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus ◽

Host Cells ◽

Hemorrhagic Disease ◽

Cytopathic Effects

AbstractAfrican swine fever virus (ASFV) is the etiological agent of African swine fever (ASF), a fatal hemorrhagic disease of domestic pigs and wild boar. The virus primarily infects macrophage and monocyte host cells, these do not grow in vitro. Many attempts have been made to establish sustainable ASFV-sensitive cell lines, but which supported only low viral replication levels of limited, mostly artificially attenuated strains of ASFV. Here, we examined the competence of a novel cell line of immortalized porcine kidney macrophages (IPKM) for ASFV infection. We demonstrated that IPKM cells can facilitate high levels (> 107.0 TCID50/mL) of viral replication of ASFV, and hemadsorption reactions and cytopathic effects were observed as with porcine alveolar macrophages when inoculated with virulent field isolates: Armenia07, Kenya05/Tk-1, and Espana75. These results suggested that IPKM may be a valuable tool for the isolation, replication, and genetic manipulation of ASFV in both basic and applied ASF research.

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Computational Analysis of African Swine Fever Virus Protein Space for the Design of an Epitope-Based Vaccine Ensemble

Pathogens ◽

10.3390/pathogens9121078 ◽

2020 ◽

Vol 9 (12) ◽

pp. 1078 ◽

Cited By ~ 1

Author(s):

Albert Ros-Lucas ◽

Florencia Correa-Fiz ◽

Laia Bosch-Camós ◽

Fernando Rodriguez ◽

Julio Alonso-Padilla

Keyword(s):

T Cell ◽

Vaccine Development ◽

De Novo ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus ◽

Economic Losses ◽

Virus Protein ◽

Hemorrhagic Disease ◽

Starting Point

African swine fever virus is the etiological agent of African swine fever, a transmissible severe hemorrhagic disease that affects pigs, causing massive economic losses. There is neither a treatment nor a vaccine available, and the only method to control its spread is by extensive culling of pigs. So far, classical vaccine development approaches have not yielded sufficiently good results in terms of concomitant safety and efficacy. Nowadays, thanks to advances in genomic and proteomic techniques, a reverse vaccinology strategy can be explored to design alternative vaccine formulations. In this study, ASFV protein sequences were analyzed using an in-house pipeline based on publicly available immunoinformatic tools to identify epitopes of interest for a prospective vaccine ensemble. These included experimentally validated sequences from the Immune Epitope Database, as well as de novo predicted sequences. Experimentally validated and predicted epitopes were prioritized following a series of criteria that included evolutionary conservation, presence in the virulent and currently circulating variant Georgia 2007/1, and lack of identity to either the pig proteome or putative proteins from pig gut microbiota. Following this strategy, 29 B-cell, 14 CD4+ T-cell and 6 CD8+ T-cell epitopes were selected, which represent a starting point to investigating the protective capacity of ASFV epitope-based vaccines.

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Short and Long-Read Sequencing Survey of the Dynamic Transcriptomes of African Swine Fever Virus and the Host Cells

Frontiers in Genetics ◽

10.3389/fgene.2020.00758 ◽

2020 ◽

Vol 11 ◽

Author(s):

Ferenc Olasz ◽

Dóra Tombácz ◽

Gábor Torma ◽

Zsolt Csabai ◽

Norbert Moldován ◽

...

Keyword(s):

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus ◽

Host Cells ◽

Long Read

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Two African Swine Fever Virus Proteins Derived from a Common Precursor Exhibit Different Nucleocytoplasmic Transport Activities

Journal of Virology ◽

10.1128/jvi.78.18.9731-9739.2004 ◽

2004 ◽

Vol 78 (18) ◽

pp. 9731-9739 ◽

Cited By ~ 9

Author(s):

A. Eulálio ◽

I. Nunes-Correia ◽

A. L. Carvalho ◽

C. Faro ◽

V. Citovsky ◽

...

Keyword(s):

Nuclear Import ◽

Mammalian Cells ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Nucleocytoplasmic Transport ◽

Proteolytic Processing ◽

Fever Virus ◽

Hemorrhagic Disease ◽

Common Precursor ◽

Green Fluorescent

ABSTRACT African swine fever virus (ASFV), a large icosahedral deoxyvirus, is the causative agent of an economically relevant hemorrhagic disease that affects domestic pigs. The major purpose of the present study was to investigate the nuclear transport activities of the ASFV p37 and p14 proteins, which result from the proteolytic processing of a common precursor. Experiments were performed by using yeast-based nucleocytoplasmic transport assays and by analysis of the subcellular localization of different green fluorescent and Myc fusion proteins in mammalian cells. The results obtained both in yeast and mammalian cells clearly demonstrated that ASFV p14 protein is imported into the nucleus but not exported to the cytoplasm. The ability of p37 protein to be exported from the nucleus to the cytoplasm of both yeast and mammalian cells was also demonstrated, and the results clearly indicate that p37 nuclear export is dependent on the interaction of the protein with the CRM-1 receptor. In addition, p37 was shown to exhibit nuclear import activity in mammalian cells. The p37 protein nuclear import and export abilities described here constitute the first report of a nucleocytoplasmic shuttling protein encoded by the ASFV genome. Overall, the overlapping results obtained for green fluorescent protein fusions and Myc-tagged proteins undoubtedly demonstrate that ASFV p37 and p14 proteins exhibit nucleocytoplasmic transport activities. These findings are significant for understanding the role these proteins play in the replication cycle of ASFV.

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African swine fever virus infects macrophages, the natural host cells, via clathrin- and cholesterol-dependent endocytosis

Virus Research ◽

10.1016/j.virusres.2015.01.022 ◽

2015 ◽

Vol 200 ◽

pp. 45-55 ◽

Cited By ~ 31

Author(s):

Inmaculada Galindo ◽

Miguel Angel Cuesta-Geijo ◽

Karolina Hlavova ◽

Raquel Muñoz-Moreno ◽

Lucía Barrado-Gil ◽

...

Keyword(s):

African Swine Fever Virus ◽

African Swine Fever ◽

Natural Host ◽

Fever Virus ◽

Host Cells

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Pathogenesis of African swine fever virus inOrnithodorosticks

Animal Health Research Reviews ◽

10.1079/ahrr200133 ◽

2001 ◽

Vol 2 (2) ◽

pp. 121-128 ◽

Cited By ~ 39

Author(s):

Steven B. Kleiboeker ◽

Glen A. Scoles

Keyword(s):

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus ◽

Sub Saharan Africa ◽

Hemorrhagic Disease ◽

Sylvatic Cycle ◽

Infectious Dose ◽

Domestic Pigs ◽

Ornithodoros Porcinus Porcinus ◽

Sub Saharan

AbstractAfrican swine fever virus (ASFV) is the only known DNA arbovirus and the sole member of the family Asfarviridae. It causes a lethal, hemorrhagic disease in domestic pigs. ASFV is enzootic in sub-Saharan Africa and is maintained in a sylvatic cycle by infecting both wild members of the Suidae (e.g. warthogs) and the argasid tickOrnithodoros porcinus porcinus. The pathogenesis of ASFV inO. porcinus porcinusticks is characterized by a low infectious dose, lifelong infection, efficient transmission to both pigs and ticks, and low mortality until after the first oviposition. ASFV pathogenesis in warthogs is characterized by an inapparent infection with transient, low viremic titers. ThusO. porcinus porcinusticks probably constitute the most important natural vector of ASFV, although both the mammalian and tick hosts are probably required for the maintenance of ASFV in the sylvatic cycle. The mechanism of ASFV transmission from the sylvatic cycle to domestic pigs is probably through infected ticks feeding on pigs. In addition toO. porcinus porcinus, a number of North American, Central American and Caribbean species ofOrnithodoroshave been shown to be potential vectors of ASFV.

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African Swine Fever Virus Protein p17 Is Essential for the Progression of Viral Membrane Precursors toward Icosahedral Intermediates

Journal of Virology ◽

10.1128/jvi.00600-10 ◽

2010 ◽

Vol 84 (15) ◽

pp. 7484-7499 ◽

Cited By ~ 20

Author(s):

Cristina Suárez ◽

Javier Gutiérrez-Berzal ◽

Germán Andrés ◽

María L. Salas ◽

Javier M. Rodríguez

Keyword(s):

Early Stage ◽

African Swine Fever Virus ◽

Transmembrane Protein ◽

African Swine Fever ◽

Integral Membrane Protein ◽

Proteolytic Processing ◽

Fever Virus ◽

Morphological Evidence ◽

Virus Protein

ABSTRACT The first morphological evidence of African swine fever virus (ASFV) assembly is the appearance of precursor viral membranes, thought to derive from the endoplasmic reticulum, within the assembly sites. We have shown previously that protein p54, a viral structural integral membrane protein, is essential for the generation of the viral precursor membranes. In this report, we study the role of protein p17, an abundant transmembrane protein localized at the viral internal envelope, in these processes. Using an inducible virus for this protein, we show that p17 is essential for virus viability and that its repression blocks the proteolytic processing of polyproteins pp220 and pp62. Electron microscopy analyses demonstrate that when the infection occurs under restrictive conditions, viral morphogenesis is blocked at an early stage, immediately posterior to the formation of the viral precursor membranes, indicating that protein p17 is required to allow their progression toward icosahedral particles. Thus, the absence of this protein leads to an accumulation of these precursors and to the delocalization of the major components of the capsid and core shell domains. The study of ultrathin serial sections from cells infected with BA71V or the inducible virus under permissive conditions revealed the presence of large helicoidal structures from which immature particles are produced, suggesting that these helicoidal structures represent a previously undetected viral intermediate.

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