@conference{
author = "Glišić, Dimitrije and Milićević, Vesna and Krnjaić, Dejan and Prodanović, Radiša and Toplak, Ivan and Radojičić, Sonja",
year = "2023",
abstract = "Afrička kuga svinja (AKS) je virusno hemoragično oboljenje domaćih i divljih
svinja visokog stepena letaliteta, koje uzrokuje enormne ekonomske gubitke u
industriji svinja. Uzročnik afričke kuge je istoimeni virus, jedini pripadnik familije
Asfarviride i roda Asfivirus (Alonso i sar., 2018). Bolest je prvi put zabeležena u Srbiji
2019. godine u populaciji domaćih svinja, a od 2020. godine i u populaciji divljih svinja.
Od tada do danas broj svinja je smanjen za 7% što je više od prosečnog pada broja
svinja u Evropi od 4%. Genom virusa AKS je dvolančana linearna DNK dužine 170-190
kbp u zavisnosti od genotipa, podgenotipa i broja ponavljajućih segmenata i kodira
sintezu 170 virusnih proteina (Blome i sar., 2020). Održavanje virusa u prirodi zavisi
od faktora sredine, prisustva prijemčivih jedinki (divljih svinja) i otpornosti virusa.
Jedan od ključnih uslova za održavanje i cirkulaciju virusa je i visoka prevalencija
infekcije kod domaćih svinja (>5%) jer se na taj način omogućava prelivanje infekcije
na divlje svinje i zatvaranje kruga prenošenja (Aguilar-Vega i sar., 2023). Letalitet kod
divljih svinja inficiranih visoko virulentnim sojem iznosi 100%. Virus ostaje infektivan
3 meseca u leševima divljih svinja koje, ukoliko nisu uklonjene, dugotrajno
predstavljaju izvor infekcije. Brzina širenja infekcije u populaciji divljih svinja u Evropi
iznosi 4-17 km godišnje (Anette i sar., 2020). Širenje AKS na veće razdaljine uslovljeno
je antropogenim faktorom. Čovek kontaktom sa zaraženim ili uginulim divljim
svinjama, hranjenjem svinja kontaminiranim proizvodima animalnog porekla,
transportom zaraženih domaćih svinja iz jednog područija u drugo predstavlja
mehanički vektor za širenje virusa. Na afričkom kontinentu zabeležena su 24 genotipa
virusa koja cirkulišu između populacija bradavičastih svinja, mekih krpelja iz roda
Ornithodorus spp. i domaćih svinja. Van Afrike zabeleženi su samo genotip I i genotip
II virusa AKS. Za trenutnu epizootiju odgovoran je genotip II virusa. Autori Gallardo i
sar. (2023) su na osnovu analize genoma virusa AKS zabaležili 24 genogrupe u okviru genotipa II virusa na tlu Evrope. Na osnovu analize B646L i E183L gena opisan je jedan
genotip virusa (genotip II). Daljom analizom B602L gena definisana su dva
podgenotipa (CVR1 i 2) sa većim brojem varijacija koje zavise od broja tačkastih
mutacija. Na osnovu analize intergenskog segmenta (I73L - I329L), mogu se opisati
četiri podgenotipa (I-IV) (Gallardo i sar., 2023).
Laboratorijska dijagnostika afričke kuge se vrši primenom molekularnih metoda.
Cilj ovog rada je bila analiza cikulišućih sojeva virusa AKS u Srbiji. Trijažna testiranja
su vršena real-time PCR testom. Dok je dalja analiza vršena primenom klasičnog PCR
testa i Sanger sekvenciranja. Za detaljnu karakterizaciju lokalnih sojeva virusa AKS
odabrano je 95 uzoraka poreklom od domacih i divljih svinja obolelih od AKS u
periodu od 2019-2023 godine. Amplifikovana su i sekvencirana četiri segmenta
virusnog genoma (B646L, E183L, B602L i intergenski region između I73L - I329L). Na
osnovu analize ovih delova genoma utvrđeno je prisustvo više različitih sojeva virusa
u Srbiji. Istovremena cirkulacija nekoliko sojeva može biti posledica spontanih
mutacija ili reintrodukcije virusa iz drugih zaraženih područja. Utvrđivanje promena
u genskom materijalu smatraju se veoma značajnim informacijama jer mogu ukazivati
na adaptaciju virusa i modifikaciju virulentnosti. Praćenje promena u genomu virusa,
porsedno daje uvid u strukturu virusnih proteina. Dugotrajna cirkulacija virusa u
populaciji divljih svinja može dovesti do pojave srednje i niskovirulentnih sojeva što
predstavlja izazov za eradikaciju bolesti. Kod domaćih svinja, srednje i niskovirulentni
sojevi mogu izazvati atipične kliničke znakove i produženi tok bolesti što otežava
postavljanje sumnje, odlaže dijagnostiku i povećava rizik od širenja bolesti.
Potencijalne promene u konzerviranom delu genoma mogu otežati dijagnostiku
virusa. Stoga su izolacija i genska karakterizacija virusa afričke kuge svinja od
izuzetnog značaja za razumevanje epizootiologije ove bolesti. Poznavanje genskih
karakteristika lokalnih sojeva virusa omogućava praćenje njihovog evolutivnog
razvoja i identifikaciju novih sojeva. Na osnovu ovih podataka treba vršiti procenu
efikasnosti preduzetih mera za suzbijanje i kontrolu bolesti. Usled nedostatka
komercijalno dostupne vackcine, primena rigoroznih biosigurnostih mera je od
najvećeg značaja za sprečavanje unosa uzročnika u populaciju domaćih svinja. Stroge
kontrole na granicama su neophodne radi sprečavanja reintrodukcije virusa iz drugih
zaraženih područija, kao i brza reakcija u aktivnim žarištima radi sprečavanja daljeg
širenja bolesti i većih ekonomskih gubitaka., African Swine Fever (ASF) is a highly lethal viral hemorrhagic disease affecting
domestic and wild pigs, causing significant economic losses in the swine industry. The
causative agent of ASF is a virus of the Asfarviridae family and Asfivirus genus (Alonso
et al., 2018). The disease was first recorded in Serbia in 2019 in domestic pig
populations, and since 2020, it has also been found in wild pig populations. Since then,
the number of pigs has decreased by 7%, which is higher than the average decline in
pig numbers in Europe (4%). The genome of the ASF virus is a double-stranded linear
DNA, ranging from 170-190 kbp in length, depending on the genotype, subgenotype,
and number of repetitive segments, encoding the synthesis of 170 viral proteins
(Blome et al., 2020). The maintenance of the virus in the environment depends on
environmental factors, the presence of susceptible individuals (wild pigs), and the
virus's ability to survive in that environment. A key condition for the maintenance and
circulation of the virus is a high prevalence of infection in domestic pigs (>5%), as it
enables the spill-over of infection to wild pigs, completing the transmission cycle
(Aguilar-Vega et al., 2023). The case fatality rate in wild pigs infected with highly
virulent strains is 100%. The virus remains infectious for 3 months in carcasses of wild
pigs, which, if not removed, serve as a long-term source of infection. The spread of
infection in the wild pig population in Europe is estimated at 4-17 km per year, with
anthropogenic factors playing a significant role in long-distance transmission (Anette
et al., 2020). Human contact with infected or dead wild pigs, feeding pigs with
contaminated animal-derived products, and the transport of infected domestic pigs
from one area to another act as mechanical vectors for virus spread. In Africa, 24
genotypes of the virus have been recorded, circulating among populations of bush
pigs, soft ticks of the Ornithodorus spp. genus, and domestic pigs. Outside of Africa,
only genotype I and genotype II of the ASF virus have been identified. The current epidemic is caused by the genotype II virus. Based on the genome analysis of the ASF
virus Gallardo et al. (2023), identified 24 genogroups within the genotype II virus in
Europe. From the analysis of the B646L and E183L genes, one virus strain (genotype
II) was described. Further analysis of the B602L gene defined two subgenotypes
(CVR1 and 2) with a higher number of variations depending on the number of point
mutations. Based on the analysis of the intergenic segment (I73L - I329L), four
subgenotypes (I-IV) can be described (Gallardo et al., 2023). Laboratory diagnostics of
African Swine Fever are conducted using molecular methods. The aim of this study
was to analyze circulating strains of ASF virus in Serbia. Screening tests were
performed using real-time PCR, while further analysis was conducted using
conventional PCR and Sanger sequencing. For a detailed characterization of local
strains of ASF virus, 95 samples from diseased domestic and wild pigs with ASF
between 2019 and 2023 were selected. Four segments of the viral genome (B646L,
E183L, B602L, and the intergenic region between I73L - I329L) were amplified and
sequenced. Based on the analysis of these genome segments, the presence of multiple
different strains of the virus was identified in Serbia. Simultaneous circulation of
several strains may result from spontaneous mutations or virus reintroduction from
other infected areas. Determining changes in the genetic material is considered highly
significant as they can indicate virus adaptation and modification of virulence.
Monitoring changes in the virus genome provides insight into the structure of viral
proteins. Prolonged circulation of the virus in the wild pig population can lead to the
emergence of moderately and low-virulent strains, posing challenges for disease
eradication. In domestic pigs, these strains can cause atypical clinical signs and
prolonged disease courses, complicating suspicion, delaying diagnosis, and increasing
the risk of disease spread. Potential changes in conserved regions of the genome can
hinder virus diagnostics. Therefore, the isolation and genetic characterization of ASF
virus strains are of utmost importance for understanding the epizootiology of this
disease. Knowledge of the genetic characteristics of local virus strains allows for
monitoring their evolutionary development and identification of new strains. Based
on these data, an assessment of the effectiveness of control measures should be
conducted. Due to the lack of commercially available vaccines, the implementation of
rigorous biosecurity measures is of paramount importance to prevent the
introduction of the pathogen into the domestic pig population. Strict controls at
borders are necessary to prevent the reintroduction of the virus from other infected
areas, along with swift responses in active outbreak areas to prevent further disease
spread and mitigate significant economic losses.",
publisher = "Beograd : Srpsko veterinarsko društvo",
journal = "34. Savetovanje veterinara Srbije, Zlatibor, 07 - 10. septembar 2023",
title = "Genska varijabilnost virusa afričke kuge svinja u Srbiji, Genetic variability of African Swine Fever virus in Serbia",
pages = "24-28",
url = "https://hdl.handle.net/21.15107/rcub_veterinar_3208"
}
