Biological characterization of African swine fever virus genotype II strains from north-eastern Estonia in European wild boar

After the extensive spread of the African swine fever virus (ASFV) genotype II in Eastern Europe, the first case of African swine fever (ASF) in Estonia was diagnosed in September 2014. By the end of 2019, 3971 ASFV-positive wild boars were found, and 27 domestic pig outbreaks were reported. A selection of ASFV isolates from wild boar and domestic pigs (during the period of September 2014–2019) was molecularly characterized using standardized genotyping procedures. One of the proven markers to characterize this virus is the central variable region (CVR) within the B602L gene. In summer 2015, a new ASFV genotype II CVR variant 2 (GII-CVR2) was confirmed in Estonia. The results suggest that the GII-CVR2 variant was only confirmed in wild boar from a limited area in southern Estonia in 2015 and 2016. In addition to GII-CVR2, a single nucleotide polymorphism (SNP) that resulted in amino acid change was identified within the genotype II CVR variant 1 (GII-CVR1). The GII-CVR1/SNP1 strain was isolated in Estonia in November 2016. Additional GII-CVR1/SNP1 cases were confirmed in two neighbouring counties, as well as in one outbreak farm in June 2017. Based on the available data, no GII-CVR2 and GII-CVR1/SNP1 have been reported by other affected European countries. The spread of variant strains in Estonia has been limited over time, and restricted to a relatively small area.

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Comparative Pathology of Domestic Pigs and Wild Boar Infected with the Moderately Virulent African Swine Fever Virus Strain “Estonia 2014”

Pathogens ◽

10.3390/pathogens9080662 ◽

2020 ◽

Vol 9 (8) ◽

pp. 662

Author(s):

Julia Sehl ◽

Jutta Pikalo ◽

Alexander Schäfer ◽

Kati Franzke ◽

Katrin Pannhorst ◽

...

Keyword(s):

Wild Boar ◽

Viral Antigen ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus ◽

Kinetic Experiment ◽

Domestic Pigs ◽

Hunting Bag ◽

North Eastern ◽

The Baltic

Endemically infected European wild boar are considered a major reservoir of African swine fever virus in Europe. While high lethality was observed in the majority of field cases, strains of moderate virulence occurred in the Baltic States. One of these, “Estonia 2014”, led to a higher number of clinically healthy, antibody-positive animals in the hunting bag of North-Eastern Estonia. Experimental characterization showed high virulence in wild boar but moderate virulence in domestic pigs. Putative pathogenic differences between wild boar and domestic pigs are unresolved and comparative pathological studies are limited. We here report on a kinetic experiment in both subspecies. Three animals each were euthanized at 4, 7, and 10 days post infection (dpi). Clinical data confirmed higher virulence in wild boar although macroscopy and viral genome load in blood and tissues were comparable in both subspecies. The percentage of viral antigen positive myeloid cells tested by flow cytometry did not differ significantly in most tissues. Only immunohistochemistry revealed consistently higher viral antigen loads in wild boar tissues in particular 7 dpi, whereas domestic pigs already eliminated the virus. The moderate virulence in domestic pigs could be explained by a more effective viral clearance.

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The African swine fever virus isolate Belgium 2018/1 shows high virulence in European wild boar

Transboundary and Emerging Diseases ◽

10.1111/tbed.13503 ◽

2020 ◽

Vol 67 (4) ◽

pp. 1654-1659 ◽

Cited By ~ 8

Author(s):

Jutta Pikalo ◽

Marie‐Eve Schoder ◽

Julia Sehl ◽

Angele Breithaupt ◽

Maryléne Tignon ◽

...

Keyword(s):

Wild Boar ◽

Virus Isolate ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus ◽

European Wild Boar ◽

High Virulence

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Comparative Pathology of Domestic Pigs and Wild Boar Infected with the Moderately Virulent African Swine Fever Virus Strain “Estonia 2014”

10.20944/preprints202007.0747.v1 ◽

2020 ◽

Author(s):

Julia Sehl ◽

Jutta Pikalo ◽

Alexander Schäfer ◽

Kati Franzke ◽

Katrin Pannhorst ◽

...

Keyword(s):

Wild Boar ◽

Viral Antigen ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus ◽

Kinetic Experiment ◽

Domestic Pigs ◽

Hunting Bag ◽

North Eastern ◽

The Baltic

Endemically infected European wild boar are considered a major reservoir of African swine fever virus in Europe. While high lethality was observed in the majority of field cases, strains of moderate virulence occurred in the Baltic States. One of these, “Estonia 2014”, led to a higher number of clinically healthy, antibody-positive animals in the hunting bag of North-Eastern Estonia. Experimental characterization showed high virulence in wild boar but moderate virulence in domestic pigs. Putative pathogenic differences between wild boar and domestic pigs are unresolved and comparative pathological studies are limited. We here report on a kinetic experiment in both subspecies. Three animals each were euthanized at 4, 7 and 10 days post infection (dpi). Clinical data confirmed higher virulence in wild boar although macroscopy and viral genome load in blood and tissues were comparable in both subspecies. The percentage of viral antigen positive myeloid cells tested by flow cytometry did not differ significantly in most tissues. Only immunohistochemistry revealed consistently higher viral antigen loads in wild boar tissues in particular 7 dpi, whereas domestic pigs already eliminated the virus. The moderate virulence in domestic pigs could be explained by a more effective viral clearance.

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First-Time Presence of African Swine Fever Virus Genotype II in Nigeria

Microbiology Resource Announcements ◽

10.1128/mra.00350-21 ◽

2021 ◽

Vol 10 (26) ◽

Author(s):

Adeyinka J. Adedeji ◽

Pam D. Luka ◽

Rebecca B. Atai ◽

Toyin A. Olubade ◽

Dupe A. Hambolu ◽

...

Keyword(s):

Food Security ◽

West Africa ◽

African Swine Fever Virus ◽

African Swine Fever ◽

Fever Virus ◽

Control Measures ◽

Virus Genotype ◽

Partial Sequencing ◽

First Time ◽

Genotype Ii

A confirmed African swine fever (ASF) outbreak in Nigeria was further investigated by partial sequencing of B464L and E183L genes of the ASF virus (ASFV). Results revealed the first-time presence of ASFV genotype II in Nigeria and West Africa. This finding has serious implications for control measures and food security.

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