Adaptive Immune Response to Vaccinia Virus LIVP Infection of BALB/c Mice and Protection against Lethal Reinfection with Cowpox Virus

Abstract

Mass vaccination has played a critical role in the global eradication of smallpox. Various vaccinia virus (VACV) strains, whose origin has not been clearly documented in most cases, have been used as live vaccines in different countries. These VACV strains differed in pathogenicity towards various laboratory animals and in reactogenicity exhibited upon vaccination of humans. In this work, we studied the development of humoral and cellular immune responses in BALB/c mice inoculated intranasally (i.n.) or intradermally (i.d.) with the VACV LIVP strain at a dose of 105 PFU/mouse, which was used in Russia as the first generation smallpox vaccine. Active synthesis of VACV-specific IgM in the mice occurred on day 7 after inoculation, reached a maximum on day 14, and decreased by day 29. Synthesis of virus-specific IgG was detected only from day 14, and the level increased significantly by day 29 after infection of the mice. Immunization (i.n.) resulted in significantly higher production of VACV-specific antibodies compared to that upon i.d. inoculation of LIVP. There were no significant differences in the levels of the T cell response in mice after i.n. or i.d. VACV administration at any time point. The maximum level of VACV-specific T-cells was detected on day 14. By day 29 of the experiment, the level of VACV-specific T-lymphocytes in the spleen of mice significantly decreased for both immunization procedures. On day 30 after immunization with LIVP, mice were infected with the cowpox virus at a dose of 46 LD50. The i.n. immunized mice were resistant to this infection, while 33% of i.d. immunized mice died. Our findings indicate that the level of the humoral immune response to vaccination may play a decisive role in protection of animals from orthopoxvirus reinfection.

Enhancing the Immunogenicity of Vaccinia Virus

“…This sampling date was chosen because we had previously demonstrated that the maximum peak of T cell-mediated immune response is reached on day 14 after the i.d. infection of BALB/c mice with the VACV LIVP [ 17 ].…”

“…Earlier, we revealed that the peak of the T cell-mediated immune response to infecting BALB/c mice with the LIVP virus is observed on day 14, while virus-specific IgG only start to be produced at this time; the IgG production reaches its maximum by day 28 [ 17 ]. Therefore, in this study, the level of T cell-mediated response of mice infected with VACV LIVP or its derivatives was assessed 14 days after the experiment had been started; the levels of IgM and IgG antibodies in these animals were analyzed on days 14 and 28.…”

“…ICS assay was performed according to a standard protocol, as described previously [ 17 ]. Briefly, splenocytes isolated from mice (2 × 10 6 cells/well) were plated in 24-well plates and stimulated with a mix of VACV-specific peptides (SPYAAGYDL, SPGAAGYDL, VGPSNSPTF, KYGRLFNEI, GFIRSLQTI, and KYMWCYSQV) or with PMA (phorbol myristate acetate, 30 ng/mL) and ionomycin (1 µg/mL).…”

Immunogenicity of Novel Live Vaccine Based on an Artificial rHN20 Strain against Emerging Fowl Adenovirus 4

“…FAdVs are double-stranded DNA viruses with a liner genome length of approximately 43-45 kb, highlighting its potential capacity to insert and deliver foreign genes, just like herpesviruses [27,28], poxviruses [29], and lentiviruses [30]. Mammalian adenoviruses have been developed into mature viral vectors, such as adenovirus-vectored Ebola and the recently emerging SARS-CoV-2 [31][32][33].…”

Comparison of the Effectiveness of Transepidemal and Intradermal Immunization of Mice with the Vacinia Virus

“…The assays were performed using the mouse IFN-γ ELISpot kit (R&D Systems, Inc., Minneapolis, MN, USA) according to the manufacturer’s instructions. The splenocytes were plated (100 μL/well) in duplicates 5 × 10 6 cells/mL and stimulated by a mixture of peptides (corresponding to VACV-specific BALB/c mice H2-d restricted epitopes): SPYAAGYDL, SPGAAGYDL, VGPSNSPTF, KYGRLFNEI, GFIRSLQTI, and KYMWCYSQV [ 18 ]. The pooled peptides (100 μL/well) were added at a concentration of 20 μg/mL for each peptide.…”