Table 1.
Origin and characteristics of monkey-derived and human-derived continuous cell lines used for ASFV in vitro studies.
| Cell Line | Species of Cell Origin | Tissue of Cell Origin | Mechanism of Immortalization | Susceptibility to Field Isolates | Susceptibility to Adapted Isolates | Advantages | Disadvantages |
|---|---|---|---|---|---|---|---|
| VERO | African green monkey: Chlorocebus sabaeus [103] | Kidney epithelial cells [103] | Spontaneous, unknown process [104] | Low susceptibility to virulent isolates (BA71, Tangani, Hinde, Huganda, Lisbon60) [61,65,66,80] | - Adapted strain from Tengani [65] - BA71V [66,67] - ASFV-G/V [61] - Lisbon60V [80] |
- Widely used to characterize function of several ASFV genes [68], proteomic analysis [68,69], mechanisms of viral entry [72,73,74], transcription and replication [69,70] - Titration by plaque formation [65,66] |
- Genomic mutation during adaptation → reduction of virulence and immunogenicity in pigs [61,67,79,80,81] |
| COS | African green monkey: Chlorocebus sabaeus [105] |
From CV1 (see below) [105] |
From CV1 (transformation with a mutant strain of Simian Virus 40 (SV40), which codes for the wild-type T-antigen) [105] |
- E70 [82] - Malawi 82 [82] - Uganda [82] - Lisbon57 [82] - Lisbon60 [20,82] - Mozam68 [82] - CC83 [82] |
- BA71V [20,30,82] - BA71ΔCD2 [81] - NH/P68 [82] - ΔEP153R [20,30,82] |
- Used for production of large amount of virus [20], and studies on virus entry mechanisms [87,88] - Plaque titration [66,82] - Construction of deleted ASFV mutants [81,89] - BA71ΔCD2 –> stability and integrity in its genome [81] - BA71 → no changes in virulence and immunogenity [81] |
- NH/P68 derived mutants → genomic mutations during passages relevant to protection [89] |
| MS | African green monkey [62,106] | Kidney [62,106] | Unknown process | - Low susceptibility to virulent to field isolate E70 [62] | - E70MS14, E70MS44, E70MS81 [62,63,90] | - Not plaque for titration [62] - Genomic mutation during adaptation → reduction of virulence and immunogenicity in pigs [62,90] |
|
| CV1 | African green monkey: Cercopithecus Aethiops [107] | Fibroblast-like cells derived from kidney tissue [107] | Transformation with a mutant strain of Simian Virus 40 (SV40), which codes for the wild-type T-antigen [107] |
- E75 [91] - Stavropol 01/80 [93] |
- E75CV1 [91] | - Plaque titration - E75CV1 → 100% protection against challenge with homologous E75 in pigs [91] but not against heterologous BA71 [92]. |
- Stavropol 01/80 → Genomic mutation, during adaptation, with reduction of virulence and immunogenicity in pigs [93] |
| Marc-145 | African green monkey Chlorocebus aethiops [94,108] | Fetal kidney epithelial cells, subpopulation of MA-104 [94,108] | MA-104 derived [94] | -D/ASF/POT/Vietnam/2019, D/ASF/POB/Vietnam/2019, although only three passages were monitored [95]. |
Unable to support the growth of ASFV Pol18/28298/Out111 [96] and ASFV-HLJ/18 [45]. | ||
| MA-104 | African green monkey: Cercopithecus aethiops [97,108] | Fetal kidney epithelial cells [97,108] | Spontaneously immortalized cell line [97] | - ASFV-G [97] - BA71 [97] - D/ASF/POT/Vietnam/2019, D/ASF/POB/Vietnam/2019 [95] - MW039157 [50] |
- MW287337 [50] | - Suitable for ASFV isolation → able to detect ASFV with a TCID50 sensitivity comparable to that of primary swine macrophages [97] - Hemadsorption [97] - Genome stability during 15 passages of a genotype II ASFV isolates [98]. |
More studies required its suitability to grow ASFV strains for large-scale vaccine production. |
| HEK293T | Human [45] | Kidney epithelial [45] | Transformation with sheared Adenovirus 5 DNA [109] | - Low susceptibility to OURT88/3 [102] and ASFV-HLJ/18 [45] | - Adapted strain from ASFV-HLJ/18 (ASFV-P121) [45] - OURT 88/3-ΔTK-GFP [102] |
- Efficiently and high replication of the attenuated virus [45] - Hemadsorption [45] - Clear cytopathic effect [45] |
ASFV-HLJ/18 → Genomic mutation during adaptation (mainly at the MGF genes) [45] → potential reduction of virulence and immunogenicity in pigs [45] |
Candidate ASFV LAVs passaged non porcine continuous cell lines and their impact in vivo are highlihted in red (promising results) or blue (unsucessful results). E70: España70; E75: España75; TCID50: 50% Tissue Culture Infectious Dose; and MGF: multiple multigene family.