Protective efficacy of an H5/H7 trivalent inactivated vaccine(H5-Re13,H5-Re14, and H7-Re4 strains) in chickens, ducks, and geese against newly detected H5N1, H5N6, H5N8, and H7N9 viruses

Some H5 viruses isolated in poultry or wild birds between 2020 and 2021 were found to be antigenically different from the vaccine strains(H5-Re11 and H5-Re12) used in China. In this study, we generated three new recombinant vaccine seed viruses by using reverse genetics and used them for vaccine production. The vaccine strain H5-Re13 contains the hemagglutinin(HA) and neuraminidase(NA) genes of an H5 N6 virus that bears the clade 2.3.4.4 h HA gene, H5-Re14 contains the HA and NA genes of an H5 N8 virus that bears the clade 2.3.4.4 b HA gene, and H7-Re4 contains the HA and NA genes of H7 N9 virus detected in 2021. We evaluated the protective efficacy of the novel H5/H7 trivalent inactivated vaccine in chickens, ducks, and geese. The inactivated vaccine was immunogenic and induced substantial antibody responses in the birds tested. Three weeks after vaccination, chickens were challenged with five different viruses detected in 2020 and 2021: three viruses(an H5 N1 virus, an H5 N6 virus, and an H5 N8 virus) bearing the clade 2.3.4.4 b HA gene, an H5 N6 virus bearing the clade 2.3.4.4 h HA gene, and an H7 N9 virus. All of the control birds shed high titers of virus and died within 4 days post-challenge, whereas the vaccinated chickens were completely protected from these viruses. Similar protective efficacy against H5 viruses bearing the clade 2.3.4.4 h or 2.3.4.4 b HA gene was observed in ducks and geese. Our study indicates that the newly updated H5/H7 vaccine can provide solid protection against the H5 and H7 N9 viruses that are currently circulating in nature.

H2 strain attenuated live hepatitis A vaccines:protective efficacy in a hepatitis A outbreak

AIM:To investigate the protective efficacy of H2 strain attenuated live hepatitis A vaccines (H2-strain vaccines) in hepatitis A (HA) outbreaks.METHODS:With the permission of their parents, 5551 pre-school and grade 1-3 primary school children were inoculated with 1 dose (10(6.5) TCID(50)) of H2 strain vaccines in a nonrandomized, controlled trial conducted in Fucheng County, Hebei Province in May 1997.Another 6485 children in the same grades and compatible in gender and age were enrolled as controls. Epidemiological and serological survey was conducted to evaluate the protective efficacy of the vaccines. ELISA was used to detect serum IgM anti-HAV.RESULTS:HA outbreak started in early May 1998, peaked in the middle of the same month, and lasted about 80 days. Overall 302 HA cases were found, 192(63.58%) were 5-9 years old. One vaccinee and 25 control cases were found to have hepatitis A, which account for 0.28% (1/356) and 5.92% (25/422) of all vaccinees and controls in the 14 villages, respectively. The protective efficacy of vaccines was 95.27% (95% CI: 85.83%-104.72%). In subjects tested for anti-HAV IgM from 13 villages, 1(0.40%) overt and 11(4.06%) asymptomatic HAV cases were found in 271 vaccinees but 21(6.69%) of overt and asymptomatic ones were found in 314 controls.CONCLUSION:H2 strain vaccines were excellent in preventing overt hepatitis A,but not so effective in preventing asymptomatic hepatitis A virus infection.A booster dose might be needed to get permanent reliable immunity.

Protective efficacy of an H5/H7 trivalent inactivated vaccine produced from Re-11, Re-12, and H7-Re2 strains against challenge with different H5 and H7 viruses in chickens

We developed an H5/H7 trivalent inactivated vaccine by using Re-11, Re-12, and H7-Re2 vaccine seed viruses, which were generated by reverse genetics and derived their HA genes from A/duck/Guizhou/S4184/2017(H5N6) (DK/GZ/S4184/17) (a clade 2.3.4.4d virus), A/chicken/Liaoning/SD007/2017(H5N1) (CK/LN/SD007/17) (a clade 2.3.2.1d virus), and A/chicken/ Guangxi/SD098/2017(H7N9) (CK/GX/SD098/17), respectively. The protective efficacy of this novel vaccine and that of the recently used H5/H7 bivalent inactivated vaccine against different H5 and H7N9 viruses was evaluated in chickens. We found that the H5/H7 bivalent vaccine provided solid protection against the H7N9 virus CK/GX/SD098/17, but only 50–60% protection against different H5 viruses. In contrast, the novel H5/H7 trivalent vaccine provided complete protection against the H5 and H7 viruses tested. Our study underscores the importance of timely updating of vaccines for avian influenza control.

Immunogenicity and protective efficacy of Vibrio harveyi pcFlaA DNA vaccine in Epinephelus awoara

The FlaA gene from Vibrio harveyi marker, was cloned into the eukaryotic expression with a short nucleotide sequence encoding the Flag vector pcDNA3.1（＋） （designated as pcFlaA）. Ninety grouper （Epinephelus awoara） were separated into three equal size groups. An experimental group was immunized with pcFlaA, Control I group was immunized with the vector pcDNA3.1（＋）, and Control 1I group was immunized with PBS. The expression of pcFlaA mRNA and protein was examined using reverse transcription-polymerase chain reaction （RT-PCR） and immunohistochemistry. We also evaluated the immunogenicity and protective efficacy of pcFlaA against V. harveyi by measuring the lymphocyte proliferation response and serum levels of specific antibody and conducting a bacterial challenge test. We successfully transfected the fish muscle with pcFlaA. The pcFlaA mRNA and protein was expressed in the muscle cells for up to one month following injection. The proliferation response of lymphocytes in fish immunized with pcFlaA was significantly higher than in control group II. Furthermore, the immunized fish generated specific antibody. The vaccination also resulted in significantly higher survival during the bacterial challenge test.

Evaluation of the Protective Efficacy of a Fused OmpK/Omp22 Protein Vaccine Candidate against Acinetobacter baumannii Infection in Mice

Acinetobocter baumannfi （A. Baumannii） is an emerging opportunistic pathogen responsible for hospital-acquired infections, and which now constitutes a sufficiently serious threat to public health to necessitate the development of an effective vaccine. In this study, a recombinant fused protein named OmpK/Omp22 and two individual proteins OmpK and Omp22 were obtained using recombinant expression and Ni-affinity purification. Groups of BALB/c mice were immunized with these proteins and challenged with a clinically isolated strain of A. boumonnii. The bacterial load in the blood, pathological changes in the lung tissue and survival rates after challenge were evaluated. Mice immunized with OmpK/Omp22 fused protein provided significantly greater protection against A. boumonnfi challenge than those immunized with either of the two proteins individually. The results provide novel clues for future design of vaccines against A. boumonnii.

A Study on Long-term Efficacy and Immunologic Persistence of Hepatitis B Plasma Vaccine Made in China

In order to demonstrate the long term protective efficacy and immunologic persistence of domestically made hepatitis B plasma derived vaccine, 371 children had been followed up for 5 to 8 years after primary vaccination (10 μg×3). The results showed that the positive rate of antibody to hepatitis B surface antigen (anti HBs) in 371 subjects was 77.6% and the geometric mean titre (GMT) of anti HBs was 47.32 IU/L. The anti HBs positive rates in the subjects who had been vaccined for five, six, seven and eight years remained 83.91%, 73.68%, 81.25% and 72.24%, respectively, while the GMTs were 59.53, 43.64, 42.21 and 46.20 IU/L, respectively. The protective efficacy rate of hepatitis B vaccine was 94.26% if both HBsAg and anti HBc were considered as infective indicators, and 88.28%, if only HBsAg positive cases were taken into account. The study indicated that the domestically made hepatitis B vaccine could provide at least 5 to 8 years protection against hepatitis B infection.

Protective effect of inactivated hepatitis A vaccine against the outbreak of hepatitis A in an open rural community

AIM： To evaluate the protective effect of inactivated hepatitis A vaccine （Healive） against hepatitis A outbreak in an emergency vaccination campaign. METHODS： During an outbreak of hepatitis A in Honghe Town, Xiuzhou District, Jiaxing City, Zhejiang Province, two nonrandomized controlled trials were conducted in September 2006. The first trial was to vaccinate 108 anti-HAV negative individuals with close contacts of the patients from September with 1 dose of an inactivated hepatYds A vaccine, HeaUve. The control group comprised of 115 individuals with close contacts of the patients before September. The second trial was to vaccinate 3365 primary and secondary school students who volunteered to receive a dose of Healive and 2572 students who did not receive Healive serving as its controls. An epidemiological survey was conducted to evaluate the pmtectk, e efficacy of the vaccine. RESULTS： A total of 136 hepatitis A cases were reported during an outbreak that started in June, peaked in August and September, and ended after December of 2006. After a massive vaccination of school children in September, the number of cases declined significantly. No hepatitis A was detected in the 108 vaccinated individuals with dose contacts of patients, whereas 4 cases of hepatitis A were found in the controls. The infection rate of hepatitis A was not significantly different in the individuals with close contacts of patients whether or not they received the vaccine （P = 0.122）. No hepatitis A was detected in the 3365 students who received the vaccine, four cases of hepatitis A were found in the controls. The infection rate of students with or without vaccination was significantly diffeent in the students who received the vaccine （0/3365 vs 4/2572, P = 0.035）. The protective efficacy of the vaccine was 100%.CONCLUSION： Inactivated hepatitis A vaccine demonstrates a good protective effect against an outbreak of hepatitis A.

Towards development of a universal dengue vaccine-how close are we?

Dengue has been ranked as one of the top emerging diseases in Asia and Latin America.Current epidemiological data may not even reflect the true burden of disease due to underreported figures.Vector control programmes have failed to contain the disease and worst of all,no specific treatment is available at the moment.Thereby,this pushes the demand for a dengue vaccine as a long-term protective approach.Despite there are numerous vaccine candidates ahead,they could be held back by different aspects in promoting vaccine implementation.Particularly for developing nations,logistics and cost are the major hurdles that need to be addressed in order to provide a quick yet affordable medical relief.As an alternative,plantbased vaccine production system is able to offer an attractive prospect given to its advantages of biocontainment warranty,low operation cost,rapid scalability and logistics flexibility.Researches that have embarked on this scope are laid out and reviewed in terms of the feasibility of plant system to serve as a biofactory for dengue vaccine.

Pros and Cons in Therapeutic Evaluation of Paraoxonase 1 in Nerve Agent Toxicity

PON 1 （Paraoxonase 1） has been proposed as an efficient catalytic bioscavenger to combat against OP （organophosphate） and CWNA （chemical warfare nerve agent） toxicity. Unlike stoichiometric bioscavengers such as butyrylcholinesterase, catalytic bioscavengers are cost effective with the advantage of eliminating all the OPs/CWNAs at low doses. Analysis of catalytic bioscavenger efficacy of PONI showed promising results by various group of researchers. Still, there are large numbers of grey areas which are not addressed so far. One of the major areas of interest is the pharmacokinetic analysis of infused PON 1 in multiple animal models. It is shown that previous studies in mice significantly increased half-life of PONI, while recent studies in guinea pigs from our group showed reduced half-life of PON1. Similar results were reported by other research groups in guinea pigs and non-human primates. The short half-life of exogenously administered PON1 in multiple animal models may be due to poor association of PON1 with its endogenous carrier, high density lipoprotein or lower doses of PON 1 or a reflection of species difference. These observations warrant the significance of thorough pharmacokinetic analysis of infused PON 1 and the development of alternative approaches for successful utility of PON 1 as an efficient medical countermeasure against OP/CWNA toxicity.

Genetic and biological characteristics of the globally circulating H5N8 avian influenza viruses and the protective efficacy offered by the poultry vaccine currently used in China

The H5N8 avian influenza viruses have been widely circulating in wild birds and are responsible for the loss of over 33 million domestic poultry in Europe, Russia, Middle East, and Asia since January 2020. To monitor the invasion and spread of the H5N8 virus in China, we performed active surveillance by analyzing 317 wild bird samples and swab samples collected from 41,172 poultry all over the country. We isolated 22 H5N8 viruses from wild birds and 14 H5N8 viruses from waterfowls. Genetic analysis indicated that the 36 viruses formed two different genotypes: one genotype viruses were widely detected from different wild birds and domestic waterfowls;the other genotype was isolated from a whopper swan. We further revealed the origin and spatiotemporal spread of these two distinct H5N8 virus genotypes in 2020 and 2021. Animal studies indicated that the H5N8 isolates are highly pathogenic to chickens, mildly pathogenic in ducks, but have distinct pathotypes in mice. Moreover, we found that vaccinated poultry in China could be completely protected against H5N8 virus challenge. Given that the H5N8 viruses are likely to continue to spread in wild birds, vaccination of poultry is highly recommended in high-risk countries to prevent H5N8 avian influenza.

Immunogenicity and protective efficacy of an inactivated SFTS vaccine candidate in mice

Severe fever with thrombocytopenia syndrome(SFTS),caused by a novel identified bunyavirus SFTS virus(SFTSV),was an emerging viral infectious disease that was firstly reported in China.There are no licensed vaccines and therapeutics against SFTSV currently.B‐Propiolactone(BPL)inactivated whole virions of SFTSV strain AH12 were prepared as experimental vaccine in different antigen dose with or without Al(OH)3 adjuvant.The experimental SFTS vaccine was a satisfying immunogen,which could efficiently trigger the development of high levels of SFTSV NP‐specific IgG antibodies and neutralizing antibodies against SFTSV Strain HB29 in BALB/c and C57/BL6 mice,and could induce SFTS virus‐specific cellular immune responses to a certain extent.A single dose of vaccine was immunogenically insufficient in BALB/c mice;the second and third dose resulted in significant boost in antibody response.The use of Al(OH)3 adjuvant resulted in higher antibody titers.The mediate‐dose of vaccine could induce as high and equivalent level of antibody titer as that of high‐dose.The experimental SFTS vaccine in mediate‐and high antigen dose with adjuvant resulted in solid protection of C57/BL6 mice against wild‐type SFTSV challenge with markedly accelerated virus clearance from blood and spleen compared with controls.The experimental SFTS vaccine prepared in this study could efficiently elicit virus specific humoral and cellular immune responses in both BALB/c and C57/BL6 mice,and could protect C57/BL6 mice against SFTS virus challenge.These results supplied evidence that inactivated vaccine was a promising vaccine candidate for the prevention of SFTSV infection.

A seven-gene-deleted African swine fever virus is safe and effective as a live attenuated vaccine in pigs

African swine fever(ASF)is a devastating infectious disease in swine that is severely threatening the global pig industry.An efficacious vaccine is urgently required.Here,we used the Chinese ASFV HLJ/18 as a backbone and generated a series of genedeleted viruses.The virulence,immunogenicity,safety,and protective efficacy evaluation in specific-pathogen-free pigs,commercial pigs,and pregnant sows indicated that one virus,namely HLJ/18-7GD,which has seven genes deleted,is fully attenuated in pigs,cannot convert to the virulent strain,and provides complete protection of pigs against lethal ASFV challenge.Our study shows that HLJ/-18-7GD is a safe and effective vaccine against ASFV,and as such is expected to play an important role in controlling the spread of ASFV.