African swine fever virus (ASFV) was first described by Montgomery in Kenya in 1921. Since then, many African, European and American countries have been affected by the disease. It is a very complex and large enveloped DNA virus with a genome of 170–190 kbp. It is classified as a unique member of the Asfarviridae family, genus Asfivirus. The virus presents high genetic and antigenic variability, with 22 different genotypes described based on the p72 sequences. African swine fever is considered a haemorrhagic disease due to the typical haemorrhagic symptoms of the hyperacute and acute forms of the diseases. However, chronic and asymptomatic forms of the disease may also be presented without these characteristic symptoms. African swine fever clinical signs may vary from a hyperacute form, with 100% mortality from days 4–7 post-infection and typical haemorrhagic symptoms, to a less common asymptomatic and chronic form that can turn animals into carriers (Sanchez-Vizcaino et al., 2012).
Protective immunity against ASFV is not fully understood. Although ASFV infection induces small proportion of neutralizing antibodies against some virion proteins, this protection is not enough for viral challenge. Cellular immunity also plays an important role in immune protection against ASFV infection, specifically, cell activity of CD8 lymphocytes and natural killer cells (NK). Cross-protection has been also demonstrated by challenging infected animals with homologous isolates (Sanchez-Vizcaino et al., 2012). A safe and effective commercial vaccine does not exist yet.
II. Vaccine Related Pathogen Genes
1. 9GL
Gene Name :
9GL
Sequence Strain (Species/Organism) :
African swine fever virus Mal
>gi|6759635|gb|AAF27970.1|AF081174_1 Mal-9GL protein [African swine fever virus]
MLHWGPKFWRTLHLYAIFFSDTPGWKEKYEAIQWILNFIESLPCTMCRHHAFSYLTKNPLTLNNSEDFQY
WTFAFHNNVNKRLNKKIISWSEYKNIYEQSILNTIEYGKTDFIGAWSSL
Molecule Role :
Virmugen
Molecule Role Annotation :
A 9GL mutant of African Swine Fever Virus is attenuated in swine and induces significant protection from challenge with wild type ASFV (Lewis et al., 2000).
Efficacy:
A 9GL mutant induces significant protection in swine from challenge with wild type ASFV (Lewis et al., 2000).
2. African Swine Fever Virus HLJ/18-7GD
a. Type:
Live, attenuated vaccine
b. Status:
Research
c. Host Species for Licensed Use:
None
d. Antigen
HLJ/18 (the first ASFV isolated in China, Pig/ Heilongjiang/2018) with genes encoding MGF505- 1R, MGF505-2R, MGF505-3R, MGF360-12L, MGF360- 13L, MGF360-14L, and CD2v deleted. (Chen et al., 2020)
e. Immunization Route
Intramuscular injection (i.m.)
f. Description
A seven-gene-deleted African swine fever virus is safe and effective as a live attenuated vaccine in pigs. (Chen et al., 2020)
3. ASFV-G-∆I177L
a. Type:
Live, attenuated vaccine
b. Status:
Research
c. Host Species for Licensed Use:
None
d. Antigen
The virus antigen was produced from Vero cells infected with a Vero-adapted ASFV strain.(Borca et al., 2021)
e. Gene Engineering of
I177L Gene
Type:
Deletion
Description:
Deletion of the I177L gene from the genome of the highly virulent ASFV strain Georgia(Borca et al., 2021)
ASFV-G-∆I177L Is alive attenuated vaccine candidate developed by deleting the I177L gene from the genome of the highly virulent pandemic ASFV strain Georgia. (Borca et al., 2021)
Efficacy:
The protective potential of this recombinant vaccine candidate was tested by a homologous sublethal challenge with ASFV following immunization. Four out of six immunized pigs remained viremia-free after ASFV infection, while the other two pigs showed similar viremic titres to control animals (Argilaguet et al., 2013).
5. NAVET-ASFVAC
a. Type:
Live, attenuated vaccine
b. Status:
Licensed
c. Location Licensed:
Vietnam
d. Host Species for Licensed Use:
Pig
e. Immunization Route
Intramuscular injection (i.m.)
f. Description
NAVET-ASFVAC Is a live attenuated vaccine licensed for restricted use only in Vietnam.(McDowell et al., 2022)
3. Burmakina et al., 2016: Burmakina G, Malogolovkin A, Tulman ER, Zsak L, Delhon G, Diel DG, Shobogorov NM, Morgunov YP, Morgunov SY, Kutish GF, Kolbasov D, Rock DL. African swine fever virus serotype-specific proteins are significant protective antigens for African swine fever. The Journal of general virology. 2016; 97(7); 1670-1675. [PubMed: 27114233].
4. Giménez-Lirola et al., 2016: Giménez-Lirola LG, Mur L, Rivera B, Mogler M, Sun Y, Lizano S, Goodell C, Harris DL, Rowland RR, Gallardo C, Sánchez-Vizcaíno JM, Zimmerman J. Detection of African Swine Fever Virus Antibodies in Serum and Oral Fluid Specimens Using a Recombinant Protein 30 (p30) Dual Matrix Indirect ELISA. PloS one. 2016; 11(9); e0161230. [PubMed: 27611939].
5. Heimerman et al., 2018: Heimerman ME, Murgia MV, Wu P, Lowe AD, Jia W, Rowland RR. Linear epitopes in African swine fever virus p72 recognized by monoclonal antibodies prepared against baculovirus-expressed antigen. Journal of veterinary diagnostic investigation : official publication of the American Association of Veterinary Laboratory Diagnosticians, Inc. 2018; 30(3); 406-412. [PubMed: 29327672].
6. Lewis et al., 2000: Lewis T, Zsak L, Burrage TG, Lu Z, Kutish GF, Neilan JG, Rock DL. An African swine fever virus ERV1-ALR homologue, 9GL, affects virion maturation and viral growth in macrophages and viral virulence in swine. Journal of virology. 2000; 74(3); 1275-1285. [PubMed: 10627538].
7. Lokhandwala et al., 2016: Lokhandwala S, Waghela SD, Bray J, Martin CL, Sangewar N, Charendoff C, Shetti R, Ashley C, Chen CH, Berghman LR, Mwangi D, Dominowski PJ, Foss DL, Rai S, Vora S, Gabbert L, Burrage TG, Brake D, Neilan J, Mwangi W. Induction of Robust Immune Responses in Swine by Using a Cocktail of Adenovirus-Vectored African Swine Fever Virus Antigens. Clinical and vaccine immunology : CVI. 2016; 23(11); 888-900. [PubMed: 27628166].
8. Sanchez-Vizcaino et al., 2012: Sanchez-Vizcaino JM, Mur L, Martinez-Lopez B. African Swine Fever: An Epidemiological Update. Transboundary and emerging diseases. 2012; ; . [PubMed: 22225967].
