Biology subjects

Rathakrishnan, A.

Publications and source records attributed to Rathakrishnan, A..

3 recordsLinked to original sources

bioRxiv2025

Early disruption of the innate-adaptive immune axis in vivo after infection with virulent Georgia2007/1 ASFV

Effective immune defence and pathogen clearance requires coordination between innate and adaptive immune responses. However, virulent African swine fever virus (ASFV), which has a high case fatality rate in pigs, causes severe disease by exploiting multiple immune evasion strategies to suppress host responses. The global spread of Georgia2007/1 and its derivatives poses a significant threat to the pig industry and global food security. Although modified live virus vaccines for ASF exist, multiple safety concerns have restricted their use internationally. Conversely, subunit vaccine candidates have not matched the protective efficacy of modified live virus vaccines. This highlights the need to further investigate ASFV-induced immunopathology to support the development of next-generation ASF vaccines. Immune dynamics in whole blood and lymphoid tissues were examined over time after oronasal infection with Georgia 2007/1. CD4+ T cells, {gamma}{delta}-TCR+ T cells and CD21+ B cells were impacted by lymphopenia, and initial immune activation was detected. However, as the disease progressed, impaired maintenance and depletion of adaptive immune cells, such as CD4+ T cells and professional antigen-presenting dendritic cells and macrophages was observed. This depletion of cells may have compromised the innate-adaptive immune axis, weakening host ability to mount a robust adaptive immune response and potentially contributing to disease progression. Differential ASFV infection profiles within the spleen were also detected, highlighting the diversity of ASFV cellular tropism. Further investigation into the innate-adaptive immune axis is needed to better understand its role in ASFV infection. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=168 SRC="FIGDIR/small/660190v1_ufig1.gif" ALT="Figure 1"> View larger version (53K): org.highwire.dtl.DTLVardef@12b96a4org.highwire.dtl.DTLVardef@af2722org.highwire.dtl.DTLVardef@13237e4org.highwire.dtl.DTLVardef@1f371f1_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2023

Deletion of the gene for the African swine fever virus BCL-2 family member A179L increases virus uptake and apoptosis, but decreases virus spread in macrophages and reduces virulence in pigs

African swine fever virus encodes proteins that inhibit apoptosis including one member of the BCL-2 family, A179L. Deletion of the A179L gene from the virulent genotype I isolate Benin 97/1 compared to Benin 97/1 expressing A179L or mock-infected macrophages, resulted in increased Caspase 3 and 7 activity, annexin V binding to surface phosphatidyl serine and DNA fragmentation, measured by terminal deoxynucleotidyl transferase nick-end labelling. These results confirmed that apoptosis was induced earlier in macrophages infected with the Benin{Delta}A179L virus. Increased cell entry of the A179L gene-deleted virus was indicated at early times since up to double the numbers of cells expressed fluorescent protein from the virus genome. Yields of infectious virus were similar over a single cycle but were significantly lower for the A179L gene-deleted virus over a multi-step growth cycle. Pigs immunised and boosted with the Benin{Delta}A179L virus showed no clinical signs, although a weak cellular response to ASFV was observed showing that the virus had replicated. The immunised pigs were not protected against challenge with the virulent parental virus Benin 97/1 although viremia was lower at 3 days post-challenge compared to the control non-immune pigs. The reduced levels of virus replication in macrophages probably limited induction of a protective immune response. The results show an important role for the A179L protein in virus replication in macrophages and virulence in pigs. IMPORTANCEAfrican swine fever virus (ASFV) causes a lethal disease of pigs that has spread extensively in Africa, Europe and Asia. The virus codes for more than 150 proteins, many of which help the virus to evade the hosts defences following infection. We investigated the effect of deleting one of these genes, A179L, from the genome of an ASFV isolate that causes death of infected pigs. A179L belongs to the BCL-2 protein family, consisting of members which promote or inhibit apoptosis with A179L belonging to the latter. Deleting the A179L gene reduced ASFV replication and spread between macrophages, its main target cells. This was correlated with an increase in cell death. Pigs infected with the virus with A179L gene deleted did not show signs of disease and no virus replication was detected in blood. A low immune response was generated but the immunised pigs were not protected when challenged with the parental deadly virus. The results show that the A179L gene is important for ASFV to replicate efficiently in cells and in animals.

microbiology↗

bioRxiv2021

Role of African swine fever virus (ASFV) proteins EP153R and EP402R in reducing viral persistence and virulence from attenuated BeninΔDP148R

The limited knowledge on the role of many of the approximately 170 proteins encoded by African swine fever virus restricts progress towards vaccine development. In this study we investigated the effect of deleting combinations of different genes from a previously attenuated virus, Benin{Delta}DP148R on: virus replication in macrophages, virus persistence and clinical signs post immunization, and induction of protection against challenge. Deletion of either EP402R or EP153R genes individually or in combination from Benin{Delta}DP148R did not reduce virus replication in vitro. However, deletion of EP402R dramatically reduced viral persistence in vivo, whilst maintaining high levels of protection against challenge. The additional deletion of EP153R (Benin{Delta}DP148R{Delta}EP153R{Delta}EP402R) further attenuated the virus and no viremia or clinical signs were observed post immunization. This was associated with decreased protection and detection of moderate levels of challenge virus in blood. Interestingly, the deletion of EP153R alone from Benin{Delta}DP148R did not result in further virus attenuation and a slight increase in virus genome copies in blood was observed at different times post immunization when compared with Benin{Delta}DP148R. These results show that EP402R and EP153R have a synergistic role in promoting viremia, however EP153R alone does not seem to have a major impact on virus levels in blood.

microbiology↗