Recombinant African swine fever virus Uncharacterized protein F165R (Mal-054)

Basic Characterization and Properties

• What is the F165R protein of African swine fever virus and how is it classified?

  F165R is an uncharacterized protein encoded by the African swine fever virus (ASFV) genome. It is found in multiple ASFV isolates, including Tick/Malawi/Lil 20-1/1983 (UniProt ID: P0CA67) and Warthog/Namibia/Wart80/1980 (UniProt ID: P0CA69) . F165R is classified as a transmembrane protein based on predictions using tools such as TMHMM . Despite its presence in the ASFV genome, the specific function of F165R remains largely unknown, hence its designation as "uncharacterized." Current research efforts are focused on determining its role in viral replication, host interactions, and potential involvement in virulence.

• How conserved is the F165R protein sequence across different ASFV isolates?

  The F165R protein shows a high degree of conservation across various ASFV isolates, suggesting functional importance. Sequence alignments between F165R from different isolates (such as Malawi and Namibia strains) reveal considerable homology . This conservation is particularly significant given the genomic diversity observed in ASFV, especially in the variable regions of the genome. The preservation of F165R sequence across geographically distinct isolates suggests evolutionary pressure to maintain its structure and potential function, making it a target of interest for understanding conserved viral mechanisms.

• What expression patterns does F165R exhibit during ASFV infection?

  Studies using CAGE-seq to map transcription start sites across the ASFV genome have revealed that F165R exhibits specific temporal expression patterns during infection. When examining differentially expressed ASFV genes during early and late infection, research has shown that some viral genes including F165R are regulated in a time-dependent manner . These expression patterns can provide insights into when F165R functions during the viral lifecycle. Generally, genes expressed early in infection often contribute to viral replication machinery or immune evasion, while late genes typically encode structural proteins or those involved in virion assembly.

Functional Roles and Interactions

Applications in Diagnostics and Vaccine Development

• Can F165R be used in diagnostic assays for ASFV detection?

  The potential of F165R as a diagnostic target depends on its immunogenicity and consistent expression during infection. Based on screening studies with ASFV-positive pig sera, F165R shows some reactivity but appears less immunodominant than proteins like E146L . For diagnostic development:

  1. ELISA-based assays: Purified recombinant F165R could be evaluated as a capture antigen for antibody detection.

  2. Multiplex assays: F165R could be included in panels with other ASFV antigens to improve sensitivity and specificity.

  3. Validation studies: Any diagnostic application would require extensive validation with diverse sera samples to determine sensitivity, specificity, and cross-reactivity profiles.

  A comprehensive diagnostic approach might combine F165R with other ASFV antigens that demonstrate stronger immunoreactivity, such as E146L, to enhance assay performance.

• What is the potential of F165R as a component in ASFV vaccine development?

  The potential of F165R as a vaccine component must be evaluated in the context of:

  1. Immunogenicity: Current evidence suggests moderate immunogenicity based on screening with pig sera .

  2. Conservation: High sequence conservation across isolates makes F165R potentially valuable for broad protection.

  3. Subunit vaccine approach: F165R could be included in multicomponent subunit vaccines alongside more immunodominant proteins like p30, p54, p72, and CD2v .

  Given the complex nature of ASFV and the challenges in developing effective vaccines, a combinatorial approach incorporating multiple viral antigens, including potentially F165R, may be more promising than single-antigen approaches. Any vaccine development would require rigorous immunogenicity and protection studies in appropriate animal models.