Tilapia Lake Virus Vaccine Development: A Review on the Recent Advances

Abstract

Tilapia tilapinevirus (or tilapia lake virus, TiLV) is a recently emerging virus associated with a novel disease affecting and decimating tilapia populations around the world. Since its initial identification, TiLV has been reported in 17 countries, often causing mortalities as high as 90% in the affected populations. To date, no therapeutics or commercial vaccines exist for TiLV disease control. Tilapia exposed to TiLV can develop protective immunity, suggesting that vaccination is achievable. Given the important role of vaccination in fish farming, several vaccine strategies are currently being explored and put forward against TiLV but, a comprehensive overview on the efficacy of these platforms is lacking. We here present these approaches in relation with previously developed fish vaccines and discuss their efficacy, vaccine administration routes, and the various factors that can impact vaccine efficacy. The overall recent advances in TiLV vaccine development show different but promising levels of protection. The field is however hampered by the lack of knowledge of the biology of TiLV, notably the function of its genes. Further research and the incorporation of several approaches including prime–boost vaccine regimens, codon optimization, or reverse vaccinology would be beneficial to increase the effectiveness of vaccines targeting TiLV and are further discussed in this review.

Discovery of two novel tilapia lake virus‐like virus isolates in the transcriptomic data of guppy fish (Poecilia reticulata)

“…Tilapia lake virus (TiLV), now formally assigned to the species Tilapia tilapinevirus , is an enveloped, 10‐segment, negative‐sense, single‐stranded RNA virus first reported from Israel (Eyngor et al, 2014) and then several countries across different continents (Tran et al, 2022). As a newly emerging aquatic viral pathogen currently with no available therapeutics or commercial vaccines for disease prevention and control (Kembou‐Ringert et al, 2023), TiLV is known for causing mass morbidity and mortality in wild and captive tilapia worldwide, posing a significant threat to the global tilapia aquaculture and the food security of millions of people (Hounmanou et al, 2018; Jansen et al, 2019). Apart from the tilapia populations, growing molecular evidence has suggested broader host ranges since the presence of TiLV in other susceptible fish species has been detected, including river barb ( Barbonymus schwanenfeldii ) (Abdullah et al, 2018), giant gourami ( Osphronemus goramy ) (Chiamkunakorn et al, 2019) and tinfoil barb ( Barbonymus schwanenfeldii ) (Abdullah et al, 2022).…”

Adjuvanting Property of Aqueous Extract of the Indian Mistletoe, Dendrophthoe falcata

“…Adjuvants play a crucial role in enhancing the e cacy of vaccines. However, in the context of farmed animals, more potent adjuvants are needed as the currently available vaccines, such as whole cell inactivated vaccines, often fail to elicit su cient protective immunity [15]. Existing options like mineral oil and alum have certain limitations, necessitating the exploration of novel adjuvants [16].…”

Fin fish vaccination as prevention in aquaculture: A review

“…This indicates the beginning of novel and third generation vaccines, in other words, gene-based technology to be licensed and endorsed for a disease-causing agent. RNA-based vaccines are similar to DNA-based vaccines where both are non-infectious, thus safe to be used (Kembou-Ringert et al, 2023). This type of vaccine has also shown outstanding results in case of coronaviruses proving it to be a potent immunostimulatory.…”

“…Basically, RNA replicon vaccines utilize an mRNA molecule containing the desired antigens enclosed within a vesicle carrier. The RNA will be translated promptly when it reaches the host's cell and subsequently expresses the target antigen (Aida et al, 2021;Kembou-Ringert et al, 2023). According to Kembou-Ringert et al (2023), it is challenging to develop mRNA vaccines as naked mRNA is susceptible to degradation by nucleases.…”

“…The RNA will be translated promptly when it reaches the host's cell and subsequently expresses the target antigen (Aida et al, 2021;Kembou-Ringert et al, 2023). According to Kembou-Ringert et al (2023), it is challenging to develop mRNA vaccines as naked mRNA is susceptible to degradation by nucleases. Besides, the size of mRNA is too large and highly negatively charged, making it incapable of passively entering the cell membrane.…”