Molecular profile of African swine fever virus (ASFV) circulating in Vietnam during 2019-2020 outbreaks

Ngo²,

et al. 2021

Preprint

This study aimed to identify potential genetic diversity among African swine fever virus (ASFV) strains circulating in central and southern Vietnam. Thirty ASFV strains were collected from domestic pigs and convalescent pigs with ASFV-infected clinical signs from 19 different provinces of central and southern Vietnam during 2019–2021. A portion of the B646L (p72) gene and the entire E183L (p54), CP204L (p30), and B602L (CVR) genes were amplified, purified, and sequenced. Web-based BLAST and MEGA-X software were used for sequence analysis. Analysis of the partial B646L (p72) gene, the full-length E183L (p54) and CP204L (p30) genes, and the central hypervariable region (CVR) of the B602L gene sequence showed that all 30 ASFV isolates belonged to genotype II and were 100% identical to the previously identified strains in Vietnam and China. Analysis of the p72, p54, and p30 regions did not indicate any change in the nucleotide and amino acid sequences among these strains in 3 years of research. No novel variant was found in the CVR within the B602L gene. Analysis of the CVR showed that these ASFV strains belong to subgroup XXXII. The results of this study revealed that these ASFVs shared high homology with ASFV isolates detected previously in northern Vietnam and China. Taken together, the results of this study and a previous study in Vietnam showed high stability and no genetic diversity in the ASFV genome.

Section: Discussionsupporting

confidence: 47%

Section: Introductionmentioning

confidence: 99%

Genotypic Characteristics of African Swine Fever Virus Maintained in Various Outbreaks in Vietnam During 2019-2021

Ngo²,

et al. 2021

Preprint

Transbound. Emerg. Dis.

“…ASF is registered as one of the most important transboundary animal diseases (TADs), notifiable to OIE, and the wide recurrence of outbreaks in various regions of the world indicates that many questions are still poorly solved concerning the biology of this devastating disease. The ASFV strains circulating in Europe and Asia are of p72 genotype II (Gallardo et al., 2014; Ge et al., 2018; Kim et al., 2020; Mai et al., 2021; Malogolovkin et al., 2019; Rajukumar et al., 2021; Vilem et al., 2020), which are generally highly virulent both in domestic pigs and wild boar causing acute disease with almost 100% lethality in animals of all ages and sexes (Blome et al., 2020; Pikalo et al., 2019, 2020). However, one major concern is its increasing and continuous trend to appear and reappear in a clinically very mild or in a completely unapparent form in areas where the disease is endemic (Lamberga et al., 2018, 2020; Nurmoja et al., 2020; Sánchez‐Vizcaíno et al., 2012, 2015).…”

Section: Discussionmentioning

confidence: 99%

“…ASF is registered as one of the most important transboundary animal diseases (TADs), notifiable to OIE, and the wide recurrence of outbreaks in various regions of the world indicates that many questions are still poorly solved concerning the biology of this devastating disease. The ASFV strains circulating in Europe and Asia are of p72 genotype II (Gallardo et al, 2014;Ge et al, 2018;Kim et al, 2020;Mai et al, 2021;Malogolovkin et al, 2019;Rajukumar et al, 2021;Vilem et al, 2020), which are generally highly virulent both in domestic pigs and TA B L E 5 African swine fever virus (ASFV) comparative antibody detection in serum samples by ELISA and IPT indicated the first positive finding in days ± standard deviation (SD) and the percentage of positives domestic pigs 7± 0 (50%) 16 ± 0 (50%) 16 ± 0 (75%) Lv17/WB/Rie1 10 (100%) 7± 0 (100%) 19.5 ± 3.6 (100%) 19.5 ± 3.6 (100%) wild boar causing acute disease with almost 100% lethality in animals of all ages and sexes (Blome et al, 2020;Pikalo et al, 2019Pikalo et al, , 2020).…”

Section: Discussionmentioning

confidence: 99%

Dynamics of African swine fever virus (ASFV) infection in domestic pigs infected with virulent, moderate virulent and attenuated genotype II ASFV European isolates

Gallardo

Soler

Nurmoja

et al. 2021

This study aimed to compare the infection dynamics of three genotype II African swine fever viruses (ASFV) circulating in Europe. Eighteen domestic pigs divided into three groups were infected intramuscularly or by direct contact with two haemadsorbent ASFVs (HAD) from Poland (Pol16/DP/ OUT21) and Estonia (Est16/WB/Viru8), and with the Latvian non‐HAD ASFV (Lv17/WB/Rie1). Parameters, such as symptoms, pathogenicity, and distribution of the virus in tissues, humoral immune response, and dissemination of the virus by blood, oropharyngeal and rectal routes, were investigated. The Polish ASFV caused a case of rapidly developing fatal acute disease, while the Estonian ASFV caused acute to sub‐acute infections and two animals survived. In contrast, animals infected with the ASFV from Latvia developed a more subtle, mild, or even subclinical disease. Oral excretion was sporadic or even absent in the attenuated group, whereas in animals that developed an acute or sub‐acute form of ASF, oral excretion began at the same time the ASFV was detected in the blood, or even 3 days earlier, and persisted up to 22 days. Regardless of virulence, blood was the main route of transmission of ASFV and infectious virus was isolated from persistently infected animals for at least 19 days in the attenuated group and up to 44 days in the group of moderate virulence. Rectal excretion was limited to the acute phase of infection. In terms of diagnostics, the ASFV genome was detected in contact pigs from oropharyngeal samples earlier than in blood, independently of virulence. Together with blood, both samples could allow to detect ASFV infection for a longer period. The results presented here provide quantitative data on the spread and excretion of ASFV strains of different virulence among domestic pigs that can help to better focus surveillance activities and, thus, increase the ability to detect ASF introductions earlier.

“…The ASFV strain used in this study was VNUA/HY/Vietnam (Genotype II, GenBank accession no. MK554698), which had a 10-nucleotide insertion (5′-GGAATATATA-3′) [ 17 , 18 ]. Primary porcine alveolar macrophages in Dulbecco’s modified Eagle medium (supplemented with 5% fetal bovine serum) were used for culturing the ASFV strain.…”

Section: Methodsmentioning

confidence: 99%

Dynamic Variations in Infrared Skin Temperature of Weaned Pigs Experimentally Inoculated with the African Swine Fever Virus: A Pilot Study

Lee

Bui

et al. 2021

Veterinary Sciences

African swine fever (ASF) is a devastating viral disease in pigs and is therefore economically important for the swine industry. ASF is characterized by a short incubation period and immediate death, making the early identification of ASF-infected pigs essential. This pilot-scale study evaluates whether the infrared thermography (IRT) technique can be used as a diagnostic tool to detect changes in skin temperature (Tsk) during the early stages of disease development in experimentally ASF-infected pigs. Clinical symptoms and rectal temperatures (Tcore) were recorded daily, and IRT readings during the experimental ASF infection were analyzed. All infected pigs died at 5–8 days post inoculation (dpi), and the incubation period was approximately 4 dpi. The average Tcore increased from 0 dpi (38.9 ± 0.3 °C) to 7 dpi (41.0 ± 0.5 °C) and decreased by 8 dpi (39.8 ± 0 °C). The maximum Tsk of ASF-infected pigs increased from 2 (35.0 °C) to 3 dpi (38.5 °C). The mean maximum Tsk observed from three regions on the skin (ear, inguinal, and neck) significantly increased from 2 to 3 dpi. This study presents a non-contact method for the early detection of ASF in infected pigs using thermal imaging at 3 days after ASF infection.