OBJECTIVE: The objective of our study was to evaluate the vaccine effectiveness (VE) of the pentavalent rotavirus vaccine (RV5) among < 5-year-old children in three provinces of China during 2020-2024 via a propensity score-matched test-negative case-control study. METHODS: Electronic health records and immunization information systems were used to obtain data on acute gastroenteritis (AGE) cases tested for rotavirus (RV) infection. RV-positive cases were propensity score matched with RV-negative controls for age, visit month, and province. RESULTS: The study included 27,472 children with AGE aged 8 weeks to 4 years at the time of AGE diagnosis; 7.98% (2,192) were RV-positive. The VE (95% confidence interval, CI) of 1-2 and 3 doses of RV5 against any medically attended RV infection (inpatient or outpatient) was 57.6% (39.8%, 70.2%) and 67.2% (60.3%, 72.9%), respectively. Among children who received the 3rd dose before turning 5 months of age, 3-dose VE decreased from 70.4% (53.9%, 81.1%) (< 5 months since the 3rd dose) to 63.0% (49.1%, 73.0%) (≥ 1 year since the 3rd dose). The three-dose VE rate was 69.4% (41.3%, 84.0%) for RVGE hospitalization and 57.5% (38.9%, 70.5%) for outpatient-only medically attended RVGE. CONCLUSION Three-dose RV5 VE against rotavirus gastroenteritis (RVGE) in children aged < 5 years was higher than 1-2-dose VE. Three-dose VE decreased with time since the 3rd dose in children who received the 3rd dose before turning five months of age, but remained above 60% for at least one year. VE was higher for RVGE hospitalizations than for medically attended outpatient visits.
Humans ; Rotavirus Vaccines/immunology* ; China/epidemiology* ; Case-Control Studies ; Child, Preschool ; Infant ; Rotavirus Infections/epidemiology* ; Male ; Propensity Score ; Female ; Vaccine Efficacy ; Gastroenteritis/virology* ; Vaccines, Attenuated ; Rotavirus

Development of a vaccine that can simultaneously induce effective mucosal immunity and systemic immunity is an ideal goal to prevent mucosal pathogenic infections. The digestive tract has many sites for inducing mucosal immunity, including the mouth, stomach and small intestine. An ideal oral viral vaccine can not only induce better local and distal mucosal immunity, but also produce better systemic immunity. The oral viral vaccine has also attracted much attention because of its painless vaccination, self-administration and other advantages. Due to the complexity of human digestive tract environment and mucosal immunity, only three oral attenuated live vaccines have been successfully marketed for human use. This review summarizes the characteristics of gastrointestinal mucosal immunity, the current types and research status of oral viral vaccines, and the challenges faced by oral viral vaccines, with the hope to facilitate the research and development of oral viral vaccines for human use in China.
Humans ; Viral Vaccines ; Vaccination ; Immunity, Mucosal ; Vaccines, Attenuated ; Vaccine Development

Influenza is an acute respiratory infectious disease that is caused by the influenza virus, which seriously affects human health. The influenza virus has frequent antigenic drifts that can facilitate escape from pre-existing population immunity and lead to the rapid spread and annual seasonal epidemics. Influenza outbreaks occur in crowded settings, such as schools, kindergartens, and nursing homes. Seasonal influenza epidemics can cause 3-5 million severe cases and 290 000-650 000 respiratory disease-related deaths worldwide every year. Pregnant women, infants, adults aged 60 years and older, and individuals with comorbidities or underlying medical conditions are at the highest risk of severe illness and death from influenza. China has experienced a influenza epidemic season dominated by A (H1N1) pdm09 subtype from mid-February to the end of April 2023, and the intensity was slightly higher than the epidemic year before the COVID-19. We may face the risk of interaction or co-circulation of respiratory infectious diseases such as COVID-19 and influenza during the coming season. Annual influenza vaccination is an effective way to prevent influenza, reduce influenza-related severe illness and death, and reduce the harm caused by influenza-related diseases and the use of medical resources. The currently approved influenza vaccines in China include trivalent inactivated influenza vaccine (IIV3), quadrivalent inactivated influenza vaccine (IIV4), and trivalent live attenuated influenza vaccine (LAIV3). IIV3 and IIV4 are produced as a split virus vaccine and subunit vaccine; LAIV3 is a live, attenuated virus vaccine. The influenza vaccine is a non-immunization program vaccine, which means that residents are voluntarily vaccinated. China CDC has issued "Technical guidelines for seasonal influenza vaccination in China" every year from 2018 to 2022. Over the past year, new research evidence has been published at home and abroad, and new influenza vaccines have been approved for marketing in China. To better guide the prevention and control of influenza and vaccination in China, the National Immunization Advisory Committee (NIAC) Technical Working Group (TWG), Influenza Vaccination TWG updated and revised the 2022-2023 technical guidelines with the latest research progress into the "Technical guidelines for seasonal influenza vaccination in China (2023-2024)." The new version has updated five key areas: (1) new research evidence－especially research conducted in China-has been added, including new estimates of the burden of influenza disease, assessments of influenza vaccine effectiveness and safety, and analyses of the cost-effectiveness of influenza vaccination; (2) policies and measures for influenza prevention and control were issued by the National Health Commission of the People's Republic of China and National Disease Control and Prevention Administrationy over the past year; (3) influenza vaccines approved for marketing in China this year; (4) composition of trivalent and quadrivalent influenza vaccines for the 2023-2024 northern hemisphere influenza season; and (5) recommendations for influenza vaccination during the 2023-2024 influenza season. The 2023-2024 guidelines recommend that all people aged 6 months and above who have no contraindications should get the influenza vaccination. For adults aged ≥18 years, co-administration of inactivated SARS-CoV-2 and influenza vaccines in separate arms is acceptable regarding immunogenicity and reactogenicity. For people under 18 years of age, there should be at least 14 days between influenza vaccination and COVID-19 vaccination. The guidelines express no preference for influenza vaccine type or manufacturer-any approved, age-appropriate influenza vaccines can be used. Combining the influenza epidemic tendency and the prevention and control strategy of multiple diseases, the technical guidelines recommend priority vaccination of the following high-risk groups during the upcoming 2023-2024 influenza season to minimize harm from influenza: (1) healthcare workers, including clinical doctors and nurses, public health professionals, and quarantine professionals; (2) adults ≥60 years of age; (3) individuals with comorbidities; (4) people living in nursing homes or welfare homes and staff who take care of vulnerable, at-risk individuals; (5) pregnant women; (6) children 6-59 months of age; (7) family members and caregivers of infants under 6 months of age; and (8) people who work in nursery institutions, primary and secondary schools, and supervision places. Children 6 months to 8 years of age who receive inactivated influenza vaccine for the first time should receive two doses, with an inter-dose interval of 4 or more weeks. Children who previously received the influenza vaccine and anyone aged 9 years or older need only one dose. LAIV is recommended only for a single dose regardless of the previous influenza vaccination. Vaccination should begin as soon as influenza vaccines become available, and preferably should be completed before the onset of the local influenza season. Repeated influenza vaccination during a single influenza season is not recommended. Vaccination clinics should provide immunization services throughout the epidemic season. Pregnant women can receive inactivated influenza vaccine at any stage of pregnancy. These guidelines are intended for use by staff of CDCs, healthcare workers, maternity and child care institutions and immunization clinic staff members who work on influenza control and prevention. The guidelines will be updated periodically as new evidence becomes available.
Adult ; Infant ; Female ; Humans ; Pregnancy ; Middle Aged ; Aged ; Adolescent ; Infant, Newborn ; Influenza Vaccines ; Influenza, Human/drug therapy* ; Seasons ; COVID-19 Vaccines ; Influenza A Virus, H1N1 Subtype ; Vaccination ; COVID-19 ; China/epidemiology* ; Vaccines, Attenuated

Porcine epidemic diarrhea (PED) is a highly contagious disease that causes high mortality in suckling piglets. Although several licensed inactivated and live attenuated vaccines were widely used, the infection rate remains high due to unsatisfactory protective efficacy. In this study, mRNA vaccine candidates against PED were prepared, and their immunogenicity was evaluated in mice and pregnant sows. The mRNA PED vaccine based on heterodimer of viral receptor binding region (RBD) showed good immunogenicity. It elicited robust humoral and cellular immune responses in mice, and the neutralizing antibody titer reached 1:300 after a single vaccination. Furthermore, it induced neutralizing antibody level similar to that of the inactivated vaccine in pregnant sows. This study developed a new design of PED vaccine based on the mRNA-RBD strategy and demonstrated the potential for clinical application.
Pregnancy ; Swine ; Animals ; Female ; Mice ; Antibodies, Viral ; Swine Diseases/epidemiology* ; Viral Vaccines/genetics* ; Antibodies, Neutralizing ; Vaccines, Attenuated ; Diarrhea/veterinary*

Influenza is an acute respiratory infectious disease caused by the influenza virus, which seriously affects human health. The influenza virus has frequent antigenic drifts that can facilitate escape from pre-existing population immunity and lead to the rapid spread and annual seasonal epidemics. Influenza outbreaks occur in crowded settings, such as schools, kindergartens, and nursing homes. Seasonal influenza epidemics can cause 3-5 million severe cases and 290 000-650 000 respiratory disease-related deaths worldwide every year. Pregnant women, infants, adults 60 years and older, and individuals with comorbidities or underlying medical conditions are at the highest risk of severe illness and death from influenza. Given the ongoing COVID-19 pandemic, some provinces in southern China had a summer peak of influenza. SARS-CoV-2 may co-circulate with influenza and other respiratory viruses in the upcoming winter-spring influenza season. Annual influenza vaccination is an effective way to prevent influenza, reduce influenza-related severe illness and death, and reduce the harm caused by influenza-related diseases and the use of medical resources. The currently approved influenza vaccines in China include trivalent inactivated influenza vaccine (IIV3), quadrivalent inactivated influenza vaccine (IIV4), and trivalent live attenuated influenza vaccine (LAIV3). IIV3 is produced as a split virus vaccine and subunit vaccine; IIV4 is produced as a split virus vaccine; and LAIV3 is a live, attenuated virus vaccine. Except for some jurisdictions in China, the influenza vaccine is a non-immunization program vaccine-voluntarily and self-paid. China CDC has issued 'Technical Guidelines for Seasonal Influenza Vaccination in China' every year from 2018 to 2021. Over the past year, new research evidence has been published at home and abroad. To better guide the prevention and control of influenza and vaccination in China, the National Immunization Advisory Committee (NIAC) Influenza Vaccination Technical Working Group updated and revised the 2021-2022 Technical Guidelines with the latest research progress into the 'Technical Guidelines for Seasonal Influenza Vaccination in China (2022-2023)'. The new version has updated five key areas: (1) new research evidence-especially research conducted in China-has been added, including new estimates of the burden of influenza disease, assessments of influenza vaccine effectiveness and safety, and analyses of the cost-effectiveness of influenza vaccination; (2) policies and measures for influenza prevention and control that were issued by the government over the past year; (3) influenza vaccines approved for marketing in China this year; (4) composition of trivalent and quadrivalent influenza vaccines for the 2022-2023 northern hemisphere influenza season; and (5) recommendations for influenza vaccination during the 2022-2023 influenza season. The 2022-2023 Guidelines recommend that vaccination clinics provide influenza vaccination services to all people aged 6 months and above who are willing to be vaccinated and have no contraindications to the influenza vaccine. For adults ≥ 18 years, co-administration of COVID-19 and inactivated influenza vaccines in separate arms is acceptable regarding immunogenicity and reactogenicity. For people under 18 years old, there should be at least 14 days between influenza vaccination and COVID-19 vaccination. The Guidelines express no preference for influenza vaccine type or manufacturer-any approved, age-appropriate influenza vaccines can be used. To minimize harm from influenza and limit the impact on the effort to prevent and control COVID-19 in China, the Technical Guidelines recommend priority vaccination of the following high-risk groups during the upcoming 2022-2023 influenza season: (1) healthcare workers, including clinical doctors and nurses, public health professionals, and quarantine professionals; (2) volunteers and staff who provide services and support for large events; (3) people living in nursing homes or welfare homes and staff who take care of vulnerable, at-risk individuals; (4) people who work in high population density settings, including teachers and students in kindergartens and primary and secondary schools, and prisoners and prison staff; and (5) people at high risk of influenza, including adults ≥ 60 years of age, children 6-59 months of age, individuals with comorbidities or underlying medical conditions, family members and caregivers of infants under 6 months of age, and pregnant women. Children 6 months to 8 years of age who receive inactivated influenza vaccine for the first time should receive two doses, with an inter-dose interval of 4 or more weeks. Children who previously received the influenza vaccine and anyone 9 years or older need only one dose. LAIV is recommended only for a single dose regardless of the previous influenza vaccination. Vaccination should begin as soon as influenza vaccines become available and preferably should be completed before the onset of the local influenza season. Repeated influenza vaccination during a single influenza season is not recommended. Vaccination clinics should provide immunization services throughout the epidemic season. Pregnant women can receive inactivated influenza vaccine at any stage of pregnancy. These guidelines are intended for use by staff of CDCs, healthcare workers, maternity and child care institutions and immunization clinic staff members who work on influenza control and prevention. The guidelines will be updated periodically as new evidence becomes available.
Adult ; Infant ; Female ; Pregnancy ; Humans ; Adolescent ; Child, Preschool ; Influenza Vaccines ; Influenza, Human/epidemiology* ; Seasons ; Pandemics ; COVID-19 ; COVID-19 Vaccines ; SARS-CoV-2 ; Vaccination ; China/epidemiology* ; Orthomyxoviridae ; Vaccines, Attenuated ; Vaccines, Combined ; Vaccines, Inactivated

Influenza is an acute respiratory infectious disease that is caused by the influenza virus, which seriously affects human health. The influenza virus has frequent antigenic drifts that can facilitate escape from pre-existing population immunity and lead to the rapid spread and annual seasonal epidemics. Influenza outbreaks occur in crowded settings, such as schools, kindergartens, and nursing homes. Seasonal influenza epidemics can cause 3-5 million severe cases and 290 000-650 000 respiratory disease-related deaths worldwide every year. Pregnant women, infants, adults 60 years and older, and individuals with comorbidities or underlying medical conditions are at the highest risk of severe illness and death from influenza. Given the ongoing COVID-19 pandemic, some provinces in southern China had a summer peak of influenza. 2019-nCoV may co-circulate with influenza and other respiratory viruses in the upcoming winter-spring influenza season. Annual influenza vaccination is an effective way to prevent influenza, reduce influenza-related severe illness and death, and reduce the harm caused by influenza-related diseases and the use of medical resources. The currently approved influenza vaccines in China include trivalent inactivated influenza vaccine (IIV3), quadrivalent inactivated influenza vaccine (IIV4), and trivalent live attenuated influenza vaccine (LAIV3). IIV3 is produced as a split virus vaccine and subunit vaccine; IIV4 is produced as a split virus vaccine; and LAIV3 is a live, attenuated virus vaccine. Except for some jurisdictions in China, the influenza vaccine is a non-immunization program vaccine-voluntarily and self-paid. China CDC has issued "Technical Guidelines for Seasonal Influenza Vaccination in China" every year from 2018 to 2021. Over the past year, new research evidence has been published at home and abroad. To better guide the prevention and control of influenza and vaccination in China, the National Immunization Advisory Committee (NIAC) Influenza Vaccination Technical Working Group updated and revised the 2021-2022 Technical Guidelines with the latest research progress into the "Technical Guidelines for Seasonal Influenza Vaccination in China (2022-2023)." The new version has updated five key areas: (1) new research evidence－especially research conducted in China－has been added, including new estimates of the burden of influenza disease, assessments of influenza vaccine effectiveness and safety, and analyses of the cost-effectiveness of influenza vaccination; (2) policies and measures for influenza prevention and control that were issued by the government over the past year; (3) influenza vaccines approved for marketing in China this year; (4) composition of trivalent and quadrivalent influenza vaccines for the 2022-2023 northern hemisphere influenza season; and (5) recommendations for influenza vaccination during the 2022-2023 influenza season. The 2022-2023 Guidelines recommend that vaccination clinics provide influenza vaccination services to all people aged 6 months and above who are willing to be vaccinated and have no contraindications to the influenza vaccine. For adults ≥18 years, co-administration of COVID-19 and inactivated influenza vaccines in separate arms is acceptable regarding immunogenicity and reactogenicity. For people under 18 years old, there should be at least 14 days between influenza vaccination and COVID-19 vaccination. The Guidelines express no preference for influenza vaccine type or manufacturer－any approved, age-appropriate influenza vaccines can be used. To minimize harm from influenza and limit the impact on the effort to prevent and control COVID-19 in China, the Technical Guidelines recommend priority vaccination of the following high-risk groups during the upcoming 2022-2023 influenza season: (1) healthcare workers, including clinical doctors and nurses, public health professionals, and quarantine professionals; (2) volunteers and staff who provide services and support for large events; (3) people living in nursing homes or welfare homes and staff who take care of vulnerable, at-risk individuals; (4) people who work in high population density settings, including teachers and students in kindergartens and primary and secondary schools, and prisoners and prison staff; and (5) people at high risk of influenza, including adults ≥60 years of age, children 6-59 months of age, individuals with comorbidities or underlying medical conditions, family members and caregivers of infants under 6 months of age, and pregnant women. Children 6 months to 8 years of age who receive inactivated influenza vaccine for the first time should receive two doses, with an inter-dose interval of 4 or more weeks. Children who previously received the influenza vaccine and anyone 9 years or older need only one dose. LAIV is recommended only for a single dose regardless of the previous influenza vaccination. Vaccination should begin as soon as influenza vaccines become available, and preferably should be completed before the onset of the local influenza season. Repeated influenza vaccination during a single influenza season is not recommended. Vaccination clinics should provide immunization services throughout the epidemic season. Pregnant women can receive inactivated influenza vaccine at any stage of pregnancy. These guidelines are intended for use by staff of CDCs, healthcare workers, maternity and child care institutions and immunization clinic staff members who work on influenza control and prevention. The guidelines will be updated periodically as new evidence becomes available.
Pregnancy ; Adult ; Infant ; Female ; Humans ; Adolescent ; Child, Preschool ; Influenza Vaccines ; Influenza, Human/prevention & control* ; Seasons ; COVID-19 ; COVID-19 Vaccines ; Pandemics ; Vaccination ; Vaccines, Attenuated ; Vaccines, Combined ; China/epidemiology*

Objective: Comparative analyses of wild-type Clostridioides difficile 630 (Cd630) strain and pathogenicity locus (PaLoc) knockout mutant (ΔPaLoc) by using RNA-seq technology. Analysis of differential expression of Cd630 wild-type strain and ΔPaLoc mutant strain and measurement of its cellular virulence changes. Lay the foundation for the construction of an toxin-attenuated vaccine strain against Clostridioides difficile. Methods: Analysis of Cd630 and ΔPaLoc mutant strains using high-throughput sequencing (RNA-seq). Clustering differentially expressed genes and screening differentially expressed genes by DESeq software. Further analysis of differential genes using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. Finally, cytotoxicity assays of ΔPaLoc and Cd630 strains were performed in the African monkey kidney epithelial cell (Vero) and the human colonic cell (Caco-2) lines. Results: The transcriptome data showed that the ΔPaLoc mutant toxin genes tcdA and tcdB were not transcribed. Compared to the wild-type strain, CD630_36010, CD630_020910,CD630_02080 and cel genes upregulated 17.92,11.40,8.93 and 7.55 fold, respectively. Whereas the hom2 (high serine dehydrogenase), the CD630_15810 (spore-forming protein), CD630_23230 (zinc-binding dehydrogenase) and CD630_23240 (galactitol 1-phosphate 5-dehydrogenase) genes were down-regulated by 0.06, 0.075, 0.133 and 0.183 fold, respectively. The GO and KEGG enrichment analyses showed that the differentially transcribed genes in ΔPaLoc were enriched in the density-sensing system, ABC transport system, two-component system, phosphotransferase (PTS) system, and sugar metabolism pathway, as well as vancomycin resistance-related pathways. Cytotoxicity assays showed that the ΔPaLoc mutant strain lost its virulence to Vero and Caco-2 cells compared to the wild-type Cd630 strain. Conclusion: Transcriptional sequencing analysis of the Cd630 and ΔPaLoc mutant strains showed that the toxin genes were not transcribed. Those other differential genes could provide a reference for further studies on the physiological and biochemical properties of the ΔPaLoc mutant strain. Cytotoxicity assays confirmed that the ΔPaLoc mutant lost virulence to Vero and Caco-2 cells, thus laying the foundation for constructing an toxin-attenuated vaccine strain against C. difficile.
Bacterial Proteins/metabolism* ; Bacterial Toxins/metabolism* ; Caco-2 Cells ; Clostridioides ; Clostridioides difficile/genetics* ; Humans ; Oxidoreductases/metabolism* ; Transcriptome ; Vaccines, Attenuated

This study attempts to develop a reference substance for the live bacteria count of Streptococcicosis live vaccines in order to evaluate the validity of live bacterial count in inspection and testing. We prepared a batch of live Streptococcus suis reference substance for live bacterial count, tested their physical property, purity, vacuum degree, remaining moisture, and determined their homogeneity, thermal stability and transportation stability. Moreover, we organized collaborative calibration to assign count values to the reference substance and determine the shelf life of the reference substance in 12 months. The results showed that the physical property, the purity, the remaining moisture and the vacuum degree of the reference substance were all in compliance with the requirements of the Chinese Veterinary Pharmacopoeia. The homogeneity test showed that the coefficient of variation of the count of the reference substance was less than 10%, indicating a good homogeneity. Transportation stability test showed that the reference substance remained active after 72 h transportation in summer and winter with the package of styrofoam boxes and ice packs. Thermal stability test showed that the reference substance could be stored for up to 3 months at -20 °C, or up to 21 days at 4 °C. According to the collaborative calibration, the reference vaccine was assigned a count value range of (8.5-12.1)×107 CFU/ampoule. The shelf life test showed that the reference substance was stable for 12 months when stored at -70 °C. The reference substance could provide a reference for the live bacterial count of Streptococcicosis live vaccines. Moreover, it could also be used as a reference to evaluate the quality of corresponding agar media.
Bacterial Load ; Reference Standards ; Vaccines, Attenuated

Recombinant bacterial vector vaccines have been widely used as carriers for the delivery of protective antigens and nucleic acid vaccines to prevent certain infectious diseases because of their ability to induce mucosal immunity, humoral immunity and cellular immunity. However, protective antigens and nucleic acids recombined into bacterial vector vaccines are difficult to be released into host cells because of the presence of bacterial cell wall. Vaccine strains that are residual in animals or livestock products may also cause environmental contamination and spread of the vaccine strains. The effective solution for these problems is to construct an auto-lysis system that can regulate the vaccine strains to grow normally in vitro while lysis in vivo. The lysis systems that have been applied in germs mainly include: the lysis system based on regulated delayed peptidoglycan synthesis, the lysis system based on the regulation of bacteriophage lysis protein and the lysis system based on the toxin-antitoxin system. In addition, a potential lysis system based on bacterial Type Ⅵ Secretion System (T6SS) is also expected to be a new method for the construction of auto-lysis strains. This review will focus on the regulatory mechanisms of these bacterial lysis systems.
Animals ; Antigens, Bacterial ; Bacterial Vaccines ; Vaccines, Attenuated ; Vaccines, DNA

To evaluate immune efficacy of the recombinant Lactobacillus casei, we constructed pLA-Newcastle disease virus (NDV)-F/L. casei and obtained the expression products. PCR amplified the NDV F gene carrying part of the major epitopes. The target gene was inserted to the shuttle plasmid pLA, and then transformed into Escherichia coli BL21 (DE3) in order to screen positive recombinant plasmid. The positive recombinant plasmid was transformed into L. casei by electroporation to construct pLA-NDV-F/L. casei. The positive strains were identified by PCR. The reactivity of the recombinant bacteria was identified by Western blotting and the protein expression was detected by indirect immunofluorescence, flow cytometry and laser confocal microscopy. The 14-day-old chickens in each group were vaccinated by oral plus nose drops. The pLA-NDV-F/L. casei twice immunization group and three times immunization group, the commercial vaccine group, the pLA/L. casei group, the unchallenge PBS and the challenge PBS group were established. IgG in serum and sIgA in the lavage fluid of intestinal, nasal and lung were detected by ELISA. The protection rate of chickens was evaluated. The results showed that 94.10% of the recombinant bacteria expressed the F protein. The recombinant protein was highly expressed on the surface of L. casei with a protein size of 62 kDa, which specifically bound to anti-NDV serum. The levels of anti-F IgG and sIgA antibodies in each test group were significantly higher than those in the control groups. The duration of antibody in the pLA-NDV-F/L. casei three-time immunization group lasted 28 days longer than that in the twice immunized group, and there was no significant difference between antibody peak values. The attack protection rates in each group of immunized pLA-NDV-F/L. casei three times, twice, attenuated vaccine, pLA/L. casei and PBS were 80%, 80%, 90%, 0% and 0%, respectively. Therefore, the antigenic protein of NDV F was successfully expressed by L. casei expression system, which has of reactogenicity and immunogenicity, and could induce protective immune responses in chickens.
Animals ; Antibodies, Viral ; Chickens ; Immunization ; Lactobacillus casei ; Newcastle disease virus ; Vaccines, Attenuated ; Viral Vaccines