A bread‐based lyophilized C‐strain CSF virus vaccine as an oral vaccine in pigs

Abstract

Summary A live attenuated cereal‐based classical swine fever (CSF) vaccine for oral application, a form of vaccine that farmers can use themselves, demonstrated the improvement of CSF control in backyard production systems in endemic areas. Due to the dependency on very low storage temperature (−20°C) of the cereal‐based oral CSF vaccine, a lyophilized cereal‐based oral vaccine has been developed and tested. Although some studies showed total protection against a virulent virus strain, the production procedure is still considered complex. In this study, the lyophilized oral CSF virus, which is easy to produce and could be kept in the form of a bread‐based vaccine at 4°C for an extended time, was tested for the ability to induce a humoral immune response in pigs. Among the materials tested as a base for the CSF virus vaccine, plain sliced bread was considered the most appropriate base because of its absorbing ability and virus titre maintenance. Titres of bread‐based lyophilized CSF virus vaccine were stable at around 3.67 log10 TCID50 per ml for 7 months at 4°C. Pigs aged 5 and 8 weeks that orally received five bread‐based lyophilized CSF virus vaccine showed seroconversion of over 90% at 14 dpv. At 28 dpv, both age groups showed 100% seroconversion. In conclusion, the bread‐based lyophilized CSF virus vaccine can be an alternative choice for oral vaccination of pigs. Due to the simple process of production and the need for less virus titre, vaccine prices could be lowered. However, vaccine thermostability has to be improved to allow the vaccine delivery to be less dependent on functioning cool chains.

Preclinical efficacy and safety analysis of gamma-irradiated inactivated SARS-CoV-2 vaccine candidates

“…Increased virus complexity can cause a weakening of the population's virulence degree; therefore, the characterization of individual variants can provide useful information for the design of a new generation of more effective and safer vaccines. Lyophilization (freeze-drying) is expressed as a process that combines the benefits of freezing and drying to obtain a dry, active, long shelf life, and easily soluble product 11 , and it is an important process for the preservation of heat-sensitive biological materials 12 .…”

Preclinical efficacy and safety analysis of gamma-irradiated inactivated SARS-CoV-2 vaccine candidates

“…Lyophilization (freezedrying) is expressed as a process that combines the benefits of freezing and drying to obtain a dry, active, long shelf life, and easily soluble product (Karagül & Altuntaş, 2018). Lyophilization is an important process for the preservation of heat-sensitive biological materials (Kunu, Jiwakanon, & Porntrakulpipat, 2019).…”

“…therefore, the characterization of individual variants can provide useful information for the design of a new generation of more effective and safer vaccines. Lyophilization (freeze-drying) is expressed as a process that combines the benefits of freezing and drying to obtain a dry, active, long shelf life, and easily soluble product 11 , and it is an important process for the preservation of heat-sensitive biological materials 12 .…”

The Development of Classical Swine Fever Marker Vaccines in Recent Years

“…In a study in Thailand, the oral form of the CSF vaccine was modified for its dependence on storage temperature by using bread as a substrate to carry the lyophilized CSF vaccine, which was better absorbed and maintained the virus titer. Seroconversion rates were 90% in piglets of different ages at 14 days after immunization and could reach 100% by 28 days [21,22]. By the end of 2020, there were 13 commercial live vaccines of classical swine fever in China, among which there are single vaccines, combined vaccines, and triple vaccines.…”