Rational design of rabies vaccine formulation for enhanced stability

Abstract

Background/aim: Vaccines are often lyophilized in order to retain their stability and efficacy for a longer period of time. However, the same lyophilization process may also cause a major degradation of the vaccine, especially during early phases of manufacturing, leading to a loss of potency of the product. Many viral diseases, such as rabies, are acute and fatal unless the vaccine is administered prior to exposure or the onset of symptoms in the case of postexposure treatment. Materials and methods:We investigated the effect of lyophilization on the stability of the virus structure during rabies vaccine manufacturing using dynamic light scattering and transmission electron microscopy. Results:Our results indicate that some viruses lose their stability and efficacy in the course of lyophilization if the pH of the cell culture medium is controlled by solvated CO 2 because the structure of the rabies virus is very sensitive to the solution pH: the virus either aggregates or its shape is deformed at low solution pH, whereas at high pH empty capsid shells are formed. Conclusion:Based on our findings, we developed a new formulation for the rabies vaccine that is stable in different buffers owing to the prevention of pH upshift upon lyophilization.

Study of Oncolytic Virus Preservation and Formulation

“…Both excessively high and excessively low pH levels can lead to a loss of viral activity. Viruses aggregate at low pH and at high pH levels, and viruses form empty capsids [ 10 ]. An unsuitable pH level can cause the coat protein to change from a folded to an unfolded state, and as a result, the Tm (melting temperature) of the virus is affected by changes in pH [ 19 ].…”

“…For example, the crystallization of buffers during the freezing process can lead to pH changes, especially in sodium phosphate buffers [ 7 ], where both overly high and overly low pH can cause virus denaturation [ 8 , 9 ]. In addition, low pH values cause viral aggregation, which may cause irreversible changes by viral denaturation [ 10 ]. Consequently, choosing the right pH is one of the key factors in achieving long-term preservation.…”

Pilot-Scale Production of Lyophilized Inactivated Rabies Vaccine Candidate in Vero Cells under Fully Animal Component-Free Conditions Using Microcarrier Technology and Laboratory Animal Trials

“…The samples were negatively stained using 2% uranyl acetate (UA). Inactivated samples were mounted on pyeloform-covered copper grids, stained with 2% uranyl acetate (UA), washed two times with sterile pure water, and monitored in a TEM (Jeol, Tokyo, Japan) [1].…”

“…Balb/c mice were immunized at days 0 and 7 by IP (intraperitoneal) route and then challenged by the intracerebral (IC) route using the Challenge Virus Standard strain (CVS-11 strain) a week after the second dose. An international reference vaccine was used to calculate potency expressed in International Units/mL (IU/mL) [1,31]. The only mouse that died between the 5 th and 14 th days post-inoculation was considered to have died from rabies.…”

“…Rabies virus, a rhabdovirus of the Lyssavirus genus, is a negative-strand virus containing a non-segmented, single-stranded, negative-sense genome RNA that encodes five proteins [1]. The rabies virus has a bullet-shaped morphology.…”