Source: MISSISSIPPI STATE UNIV submitted to
DEVELOPMENT OF A DUAL LIVE ATTENUATED VACCINE TO PREVENT MOTILE AEROMONAS SEPTICEMIA AND ENTERIC SEPTICEMIA OF CATFISH
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
EXTENDED
Funding Source
AFRI COMPETITIVE GRANT
Reporting Frequency
Annual
Accession No.
1028156
Grant No.
2022-67011-36574
Project No.
MISV-081760
Proposal No.
2021-09518
Multistate No.
(N/A)
Program Code
A7101
Project Start Date
Jan 1, 2022
Project End Date
Dec 31, 2024
Grant Year
2022
Project Director
Gomaa, B. M.
Recipient Organization
MISSISSIPPI STATE UNIV
(N/A)
MISSISSIPPI STATE,MS 39762
Performing Department
Dept of Comparative Biomed Sci
Non Technical Summary
Outbreaks caused by virulent Aeromonas hydrophila (vAh) since 2009 resulted in significant losses of catfish from U.S. aquaculture. This disease is a very high priority for the catfish industry; it has had a serious impact on the region of west Alabama and east Mississippi, and it has become the most commonly diagnosed disease in the Mississippi State University and Auburn University fish diagnostic laboratories serving these regions. There are limitations in the current therapeutic and preventative strategies against vAh. The problem is exacerbated by A. hydrophila strains resistant to the FDA approved antimicrobial (Terramycin®). Thus, in this research I aim to develop a disease prevention method. Specifically, this project will focus on vaccine development and efficacy evaluation in channel catfish. Our preliminary data revealed that recombinant vAh surface proteins (Fim, FimMrfG, ATPase, Tdr, and OmpA1) are effective in protecting catfish against MAS. Furthermore, live attenuated Edwardsiella ictaluri vaccine strain ESC-NDKL1 is an effective carrier for these antigens using a recombinant expression system. The central hypothesis is that expression of vAh surface proteins in a live attenuated E. ictaluri vaccine strain will provide significant protection against both MAS caused by vAh and ESC caused by E. ictaluri, and that vAh stimulates significant inflammation in the adaptive immune response in catfish. In this project, I will complete two objectives: 1) Construction and evaluation of a recombinant live attenuated vaccine strain as a dual strategy to prevent MAS and ESC. The goal is to develop and evaluate stable recombinant ESC-NDKL1 strains expressing one, two, or three vAh surface antigens. 2) Determine effects of vAh strain ML09-119 on the catfish immune response. The goal is to determine the role of innate and adaptive immune components in the channel catfish response to vAh. This research will yield an important tool and information to help combat two diseases that heavily impact the catfish industry.
Animal Health Component
100%
Research Effort Categories
Basic
100%
Applied
(N/A)
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
3110810104034%
3110810109033%
3110810110033%
Knowledge Area
311 - Animal Diseases;

Subject Of Investigation
0810 - Finfish;

Field Of Science
1040 - Molecular biology; 1090 - Immunology; 1100 - Bacteriology;
Goals / Objectives
Aeromonas hydrophila is a Gram-negative opportunistic pathogen that affects farm-raised catfish, which is the largest aquaculture industry in the U.S. Although it is historically considered a secondary pathogen, outbreaks caused by A. hydrophila as a primary pathogen began in 2009 and caused heavy losses of market-size catfish in Alabama and Mississippi. In particular, comparative genomics revealed that the vAh isolates have approximately 54 unique and distinguishable genomic features. Options for treatment of vAh outbreaks are limited. Only one antibiotic feed additive, oxytetracycline (Terramycin®), is currently labeled by the U.S. Food and Drug Administration for MAS. Improper or continuous antibiotic use has potentialto increase antimicrobial resistance in A. hydrophila.An effective vaccination method to control MAS caused by vAh in catfish aquaculture could reduce industry use of antimicrobials to treat the disease. Under two USDA AFRI grants funded through the Animal Health program, our group showed that several recombinant surface and extracellular proteins unique to vAh have vaccine efficacy. Examples include major outermembrane protein (OmpA), fimbrial biogenesis outer membrane usher protein (Fim), fimbrialprotein (MrfG), TonB dependent receptor (Tdr), and an ATPase. Furthermore, our group discovered that a patented attenuated Edwardsiella ictaluri vaccine strain (ESC-NDKL1; ΔsdhCΔgcvPΔfrdA mutant of E. ictaluri strain (93-146) is an effective carrier for these antigens using a recombinant expression system.The long-range goal of my work is to develop a stable recombinant live attenuated ESC-NDKL1 that acts as a dual vaccine to provide protection against MAS caused by vAh and ESC caused by E. ictaluri. My hypothesis is that expression of vAh surface proteins in a live attenuated E. ictaluri vaccine will provide significant protection against MAS, and that vAh stimulates significant inflammation in the catfish immune response.My first objectives for this project is to construct and evaluate a recombinant live attenuated vaccine strain as a dual strategy to prevent MAS and ESC. I will construct stable recombinant attenuated E. ictaluri with chromosomal integration of one, two, or three genes encoding vAh protective antigens under control of the T7lac promoter. I will evaluate vaccine efficacy of recombinant attenuated ESC-NDKL1 strain(s) as dual protection against MAS and ESC by immersion and oral vaccination methods.My second objective is to determine effects of vAh strain ML09-119 on the catfish immune response. I will determine the role of innate and adaptive immune components in the channel catfish response to vAh, and I will correlate this with vAh tissue distribution during infection.Important activities that will be completed in this project include:Insertion of one, two, and three vAh genes in live attenuated E. ictaluri chromosome.Real time PCR analysis to confirm the expression of the inserted vAh genes in live attenuated E. ictaluri chromosome.Fish challenge experiment to determine the efficacy of the recombinant vaccine strains to prevent MAS and ESC in catfish.Real time PCR analysis to determine the effects of vAh on expression of immune-related genes in catfish immune-competent tissues following infection with a sublethal dose of vAh.
Project Methods
We determined that several recombinant surface and extracellular proteins unique to vAh have vaccine efficacy. Examples include major outer membrane protein (OmpA), fimbrial biogenesis outer membrane usher protein (Fim), fimbrial protein (MrfG), TonB dependent receptor (Tdr), and an ATPase. Furthermore, we discovered that a patented attenuatedEdwardsiella ictaluri vaccine strain (ESC-NDKL1; ΔsdhCΔgcvPΔfrdA mutant of E. ictaluri strain 93-146) is an effective carrier for these antigens using a recombinant expressionsystem. Our efforts will focus on developing a stable recombinant live attenuated ESC-NDKL1that acts as a dual vaccine to provide protection against MAS caused by vAh and ESCcaused by E. ictaluri. In this project, I will construct stable recombinant attenuated E. ictaluri with chromosomal integration of one, two, or three genes encoding vAh protective antigens under control of the T7lac promoter. The vaccine efficacy of recombinant attenuated ESC-NDKL1 strain(s) will be evaluated by the ability of the recombinant vaccine strains to protect against MAS and ESC by oral and immersion delivery methods. Additionally, I will determine the role of innate and adaptive immune components in the channel catfish response to vAh, and I will correlate this with vAh tissue distribution during infection. Real time PCR will be used to evaluate effects of vAh on expression of immune-related genes in catfish immune-competent tissues following infection with a sublethal dose.Therefore, my goals will be to 1) construct and evaluate a recombinant live attenuated vaccine strain as a dual strategy to prevent MAS and ESC and 2) determine effects of vAh strain ML09-119 on the catfish immune response. Our success in this study will be evaluated by the development of at least one vaccine strain can be practically used to help producers control two diseases that have heavy impacts on the catfish industry.

Progress 01/01/22 to 10/24/23

Outputs
Target Audience:The target audience for this project is commercial catfish producers. The goal is to develop a preventive method to reduce prevalence and impact of disease caused by virulent Aeromonas hydrophila (vAh) and Edwardsiella ictaluri. Another target audience is veterinarians and fish diagnosticians. The goal is to understand the effects of vAh strain ML09-119 on the catfish immune response. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?At Mississippi State University, this project provided me with research training in microbiological methods, molecular biology, immunology, and pathogenesis research in fish. I also received training in teaching graduate classes and professional student classes, and I gained professional development training in preparation for my career in animal health research and teaching in academia. How have the results been disseminated to communities of interest?Results were disseminated to fish health researchers, diagnosticians, and veterinarians through presentations at Aquaculture America, the International Symposium for Aquatic Animal Health, American Society for Microbiology, and Mississippi Academy of Science, and further dissemination will be done through peer-reviewed publications and the Conference for Research Workers in Animal Diseases. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Aim 1. In a previous USDA grant, our group showed that recombinant vAh proteins Fim, Fim A, FimMrfG, OmpAI, TonB, and ATPase have potential as vaccine antigens against vAh infection. In addition, live attenuated Edwardsiella ictaluri vaccine strain ESC-NDKL1 is a potentially effective delivery vehicle for vAh antigens. We inserted genes encoding these vAh proteins into the deleted frdA, sdhC, and gcvP gene sites in ESC-NDKL1 using homologous recombination. This resulted in 32 strains derived from ESC-NDKL1, each with different combinations of antigen-encoding genes inserted in the frdA, sdhC and gcvP deletion sites. We performed vaccine trials for recombinant strains using vaccine delivery by intraperitoneal (IP) injection (1x105 CFU/fish). Recombinant ESC-NDKL1 strains expressing one or two vAh antigens showed significant protection against wild-type strain ML09-119, but only four recombinant strains (each expressing two vAh antigens) showed significantly improved protection compared to vaccination with non-recombinant ESC-NDKL1. The vaccine strains expressing two or three vAh antigens showed improved protection compared to the recombinant strains expressing a single antigen, with recombinant ESC-NDKL1 strains expressing three vAh antigens showed the best protection. Aim 2. The aim of this study was to understand tissue distribution of virulent Aeromonas hydrophila (vAh) in channel catfish during motile Aeromonas septicemia and the immune response of channel catfish immune competent organs in response to vAh infection. Specific pathogen free catfish fingerlings were injected intra-peritoneally (IP) with 1X104 CFU in 100 µl of BHI per fish. The control group was injected with sterile BHI. After infection, 10 fish from each group were randomly selected. The anterior kidney (AK), spleen, and liver were collected, and each organ divided into two portions. The first portion was placed immediately into RNase-free tubes (Thermo Fisher Scientific) with 10vol of RNAlater(Ambion, Austin, TX) to determine the expression profile of immune-related genes using qPCR. The second portion was used for bacterial quantification. Tissues were collected at 2h, 4h, 8h, 12h, 24h, 48h, 72h, and 5 days post-infection (pi) for bacterial quantification, and relative gene expression was performed at 2h, 4h, 12h, 24h, 72h, 7d, 14d, and 21dpi. For bacterial dissemination, spleen, liver and trunk kidney were aseptically collected in PBS. The resulting suspensions were serially diluted, and 50μl aliquots were spread on BHI plates for quantification. Colony counts were determined 24 hr post incubation. The number of CFU/g of tissue were calculated for each fish and transformed by taking the base 10 logarithm to improve normality. Three fresh dead fish following challenge were sampled to confirm vAh as the cause of mortality. For determining the expression profile of immune-related genes, RNA was isolated from tissues according to the manufacturer's protocol for Fast RNA™ SPIN Kit for Microbes with a FastPrep-24™ (MP Biomedicals, Santa Ana, CA). Maxima First Strand cDNA Synthesis Kit for RT-qPCR (Thermo Scientific, USA) was used to convert total RNAs into cDNA according to the manufacturer's instructions. Thirteen innate and adaptive catfish immune-related genes were used in this study to evaluate catfish immune response to vAh infection. The genes that encode toll-like receptors (TLR-4 and TLR-5), Th1 type cytokine interferon gamma (IFN-γ), proinflammatory cytokines (interleukin 1 beta (IL-1β), tumor necrosis factor alfa (TNF-α), chemokine interleukin 8 (IL8), adaptive immune-related gene clusters (CD4-1, CD4-2, CD8α, and CD8β), major histocompatibility complexes (MHCI and MHCII), and B cell specific gene immunoglobulin (IgM) were selected. Specific objectives met Aim 1. Thirty-two recombinant live attenuated vaccine candidate strains were constructed by inserting one, two, and three vAh antigen-encoding genes in the chromosome of live attenuated E. ictaluri vaccine ESC-NDKL1. Expression of the inserted vAh genes from the ESC-NDKL1chromosome were confirmed by real time RT-PCR. The vaccine efficacy of ESC-NDKL1 recombinant strains (expressing one, two, or three vAh antigens) to protect catfish fingerlings against motile Aeromonas septicemia was done through IP infection method. Aim 2. Quantification of vAhML09-119 in channel catfish tissues was done. A total of 10 fish per timepoint were randomly sampled at 2h, 4h, 8h, 12h, 24h, 48h, 72 hours, 5 d, 7 d, 14 d, and 21 days post-infection, and effects of vAh infection on expression of immune-related genes in catfish immune-competent tissues was evaluated. The selected genes encode TLR-4, TLR-5, IL-1β, IL8, IFN-γ, CD4-1, CD4-2, CD8α, CD8β, MHCI, MHCII, and IgM. Significant results achieved We discovered that the vaccine strains expressing two vAh antigens show improved protection compared to the recombinant strains expressing a single vAh antigen. Recombinant strains expressing two vAh genes (ESC-NDKL1::ATPase/ FimMrfG, ESC-NDKL1::Fim/ FimMrfG, ESC-NDKL1::Fim/ OmpAI and ESC-NDKL1::Tdr/FimMrfG) showed significant protection against wild type ML09-119 compared to non-recombinant ESC-NDKL1 with relative percent survival (RPS) values of. 55.72%, 60.18%, 61.74%, and 54.81%. Four triple recombinant ESC-NDKL1 strains (ESC-NDKL1::fimMrfG::ompA::fimA, ESC-NDKL1::atpase::fimMrfG::ompA, ESC-NDKL1::fim::fimMrfG::ompA and ESC-NDKL1::atpase::tdr::fim) showed the best protection with RPS values of 77.93%, 63.18%, 67.74%, and 82.35%. vAh rapidly spread to fish tissues and caused high mortality following IP infection. At 2 h post-infection, vAh was detected in anterior kidney, liver, and spleen. Spleen had the most vAh at 4 h post challenge. The highest concentration of vAh was detected at 12 h post-infection in spleen, anterior kidney, and liver. Liver had the highest concentration of vAh at 24 h post-infection, while spleen had the highest concentration at 48 h. At 72 h post infection, the vAh concentration was markedly decreased in anterior kidney, followed by a decrease in spleen at 5 days post infection. The relative expression of proinflammatory genes and innate and adaptive immune-related genes was detected using real-time PCR. The data suggested that vAh induces a strong inflammatory response in AK, spleen, and liver, followed by apoptotic and/ or necrotic death of cells, especially in the liver. This leads to a virtually total inability of liver cells to express MHC molecules or TLR genes for pathogen identification and elimination. We speculate that this organ failure could be the main cause of catfish mortalities within 24 hpi. Additionally, our findings revealed that surviving catfish were able to develop a primary immune response and possibly generation of memory B "antigen-specific cells" against MAS. These findings, along with bacterial quantification, improve our understanding of MAS pathogenesis and inform vaccine development strategies. Key outcomes or other accomplishments realized My results confirm that recombinant live attenuated Edwardsiella ictaluri expressing fimbrial and outer membrane vAh antigens provide significant protection against motile Aeromonas septicemia. It was interesting to note that all the most effective double or triple recombinant vaccine candidates included at least one fimbrial antigen, and three of them included both FimMrfG and Fim or FimMrfG and FimA. Immersion vaccination with non-recombinant live attenuated ESC-NDKL1 vaccine gives a cross protection against vAh through IP infection.. My pathogenesis research shows rapid dissemination of vAh in catfish tissues following experimental infection with predilection for spleen and liver. Virulent A. hydrophila induces a strong systemic inflammatory response in catfish during MAS, which probably contributes to catfish mortalities in response to MAS.

Publications

  • Type: Conference Papers and Presentations Status: Other Year Published: 2023 Citation: Zinnurine, S., Gomaa, B., Chowdhury, QMMK., Tekedar, H., & Lawrence, M. Role of RTX toxin in the pathogenesis of virulent Aeromonas hydrophila. MSU College of Veterinary Medicine Research Day, August 17, 2023.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2023 Citation: Basant M. Gomaa, Hossam A. Abdelhamed, Michelle Banes, Saida Zinnurine, Mark L. Lawrence. Quantification of virulent Aeromonas hydrophila ML09-119 in channel catfish organs following IP injection. Mississippi Academy of Science. Biloxi, MS. February 2023.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2022 Citation: Basant M. Gomaa, Hasan Tekedar, Hossam A. Abdelhamed, Mark L. Lawrence. Developing a Dual Live Attenuated Vaccine to Prevent Motile Aeromonas Septicemia and Enteric Septicemia of Catfish. ISAAH 2022, Santiago, Chile. September 2022.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2022 Citation: Saida Zinnurine, Basant Gomaa, Q M Monzur Kader Chowdhury, Hasan C. Tekedar, and Mark L. Lawrence. Mutation of chitinase and RTX toxin genes for determining their role in the pathogenesis of virulent Aeromonas hydrophila. South Central Branch of the American Society for Microbiology, October 2022.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2022 Citation: Mark L. Lawrence, Hasan Tekedar, Basant Gomaa, Hossam Abdelhamed, Salih Kumru, Jochen Blom, and Attila Karsi. Use of comparative genomics to understand Aeromonas pathotypes and design a recombinant vaccine strategy. Physiological Insights Towards Improving Fish Culture Symposium. Triennial Aquaculture America 2022 conference in San Diego, CA. February 2022.


Progress 01/01/22 to 12/31/22

Outputs
Target Audience: The target audience for this project is commercial catfish producers. The goal is to develop a preventive method to reduce prevalence and impact of disease caused by virulent Aeromonas hydrophila (vAh) and Edwardsiella ictaluri. Another target audience is veterinarians and fish diagnosticians. The goal is to understand the effects of vAh strain ML09-119 on the catfish immune response. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?At Mississippi State University, this project is providing me with research training in microbiological methods, molecular biology, immunology, and pathogenesis research in fish. I am also getting training in teaching in graduate classes and professional student classes. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals? Vaccine trials evaluating recombinant ESC-NDKL1 strains expressing three vAh antigens to protect catfish fingerlings against MAS caused by vAh. Vaccine trials evaluating efficacy of the candidate live attenuated vaccine strains as a potential dual vaccine to prevent both MAS and ESC. Vaccine trials evaluating efficacy of the candidate live attenuated vaccine strain(s) through oral vaccination. Determining the response of catfish immunecompetent tissues to vAh strain ML09-119 using real-time PCR.

Impacts
What was accomplished under these goals? Major activities completed Aim 1. In a previous USDA grant, our group showed that recombinant vAh proteins Fim, Fim A, FimMrfG, OmpAI, TonB, and ATPase have potential as vaccine antigens against vAh infection. In addition, live attenuated Edwardsiella ictaluri vaccine strain ESC-NDKL1 is a potentially effective delivery vehicle for vAh antigens. We inserted genes encoding these vAh proteins into the deleted frdA, sdhC, and gcvP gene sites in ESC-NDKL1 using homologous recombination. This resulted in 32 strains derived from ESC-NDKL1, each with different combinations of antigen-encoding genes inserted in the frdA, sdhC and gcvP deletion sites. We performed vaccine trials for recombinant strains using vaccine delivery by intraperitoneal (IP) injection (1x105 CFU/fish). Recombinant ESC-NDKL1 strains expressing one or two vAh antigens showed significant protection against wild-type strain ML09-119, but only four recombinant strains (each expressing two vAh antigens) showed significantly improved protection compared to vaccination with non-recombinant ESC-NDKL1. The vaccine strains expressing two vAh antigens showed improved protection compared to the recombinant strains expressing a single antigen. Aim 2. The aim of this study is to understand tissue distribution of virulent Aeromonas hydrophila (vAh) in channel catfish during motile Aeromonas septicemia. Specific pathogen free catfish fingerlings were infected intra-peritoneally with 1x105 CFU/fish ofvAh strain ML09-119. A total of 10 fish per time point were randomly sampled for vAh quantification at 2, 4, 8, 12, 24, 48, 72 h, and 5 days post-infection. Liver, spleen, and trunk kidney were aseptically collected in PBS. The resulting suspensions were serially diluted, and 50μl aliquots were spread on BHI plates for quantification. Colony counts were determined 24 hr post incubation. The number of CFU/g of tissue were calculated for each fish and transformed by taking the base 10 logarithm to improve normality. Three fresh dead fish following challenge were sampled to confirm vAh as the cause of mortality. Specific objectives met Aim 1. Thirty-two recombinant live attenuated vaccine candidate strains were constructed by inserting one, two, and three vAh antigen-encoding genes in the chromosome of live attenuated E. ictaluri vaccine ESC-NDKL1. Expression of the inserted vAh genes from the ESC-NDKL1chromosome were confirmed by real time RT-PCR. The vaccine efficacy of ESC-NDKL1 recombinant strains (expressing one or two vAh antigens) to protect catfish fingerlings against motile Aeromonas septicemia was done. Testing the vaccine efficacy of recombinant ESC-NDKL1 expressing three vAh antigens is pending. Aim 2. Quantification of vAhML09-119 in channel catfish tissues has been done. A total of 10 fish per timepoint were randomly sampled at 2h, 4h, 8h, 12h, 24h, 48h, 72 hours, 5 d, 7 d, 14 d, and 21 days post-infection to evaluate effects of vAh infection on expression of immune-related genes in catfish immune-competent tissues. The selected genes to be evaluated encode TLR-4, TLR-5, IL-1β, IL8, IFN-γ, CD4-1, CD4-2, CD8α, CD8β, MHCI, MHCII, and IgM. Significant results achieved We discovered that the vaccine strains expressing two vAh antigens show improved protection compared to the recombinant strains expressing a single vAh antigen. Recombinant strains expressing two vAh genes (ESC-NDKL1::ATPase/ FimMrfG, ESC-NDKL1::Fim/ FimMrfG, ESC-NDKL1::Fim/ OmpAI and ESC-NDKL1::Tdr/FimMrfG) showed significant protection against wild type ML09-119 compared to non-recombinant ESC-NDKL1. Candidate live attenuated vaccine strains expressing three vAh antigens in a live attenuated Edwardsiella ictaluri vaccine were constructed. vAh rapidly spread to fish tissues and caused high mortality following IP infection. At 2 h post-infection, vAh was detected in anterior kidney, liver, and spleen. Spleen had the most vAh at 4 h post challenge. The highest concentration of vAh was detected at 12 h post-infection in spleen, anterior kidney, and liver. Liver had the highest concentration of vAh at 24 h post-infection, while spleen had the highest concentration at 48 h. At 72 h post infection, the vAh concentration was markedly decreased in anterior kidney, followed by a decrease in spleen at 5 days post infection. Key outcomes or other accomplishments My results confirm that recombinant live attenuated Edwardsiella ictaluri expressing fimbrial and outer membrane vAh antigens provide significant protection against motile Aeromonas septicemia. My pathogenesis research shows rapid dissemination of vAh in catfish tissues following experimental infection with predilection for spleen and liver.

Publications

  • Type: Conference Papers and Presentations Status: Other Year Published: 2023 Citation: Basant M. Gomaa, Hossam A. Abdelhamed, Michelle Banes, Saida Zinnurine, Mark L. Lawrence. Quantification of virulent Aeromonas hydrophila ML09-119 in channel catfish organs following IP injection. Mississippi Academy of Science. Biloxi, MS. February 2023.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2022 Citation: Basant M. Gomaa, Hasan Tekedar, Hossam A. Abdelhamed, Mark L. Lawrence. Developing a Dual Live Attenuated Vaccine to Prevent Motile Aeromonas Septicemia and Enteric Septicemia of Catfish. ISAAH 2022, Santiago, Chile. September 2022.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2022 Citation: Saida Zinnurine, Basant Gomaa, Q M Monzur Kader Chowdhury, Hasan C. Tekedar, and Mark L. Lawrence. Mutation of chitinase and RTX toxin genes for determining their role in the pathogenesis of virulent Aeromonas hydrophila. South Central Branch of the American Society for Microbiology, October 2022.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2022 Citation: Mark L. Lawrence, Hasan Tekedar, Basant Gomaa, Hossam Abdelhamed, Salih Kumru, Jochen Blom, and Attila Karsi. Use of comparative genomics to understand Aeromonas pathotypes and design a recombinant vaccine strategy. Physiological Insights Towards Improving Fish Culture Symposium. Triennial Aquaculture America 2022 conference in San Diego, CA. February 2022.