Optimal time for vaccination against Peste des petits ruminants (PPR) disease in goats in humid tropical zone in southern Nigeria

Investigation of the incidence of peste des petits ruminants (PPR) disease in goats revealed seasonality in the natural occurrence of PPR disease in the environment. Tissue culture rinderpest vaccine was shown effective in protecting goats against the disease. The optimal time for vaccinating goats against PPR disease was when the least number of animals were incubating the disease. In the tropical humid zone, as in West Africa, the optimal time for vaccination against the PPR disease is from late November to middle of December.     

Rapid quality control of a live attenuated Peste des petits ruminants (PPR) vaccine by monoclonal antibody based sandwich ELISA.

Peste des petits ruminants (PPR) is a highly contagious and economically important viral disease of goats and sheep. A homologous Vero cell-based attenuated PPR vaccine developed in our laboratory and used extensively throughout the country, is available for control of PPR. The presently used quality control test, titration in Vero cells for PPR virus titre in vaccine batches, takes at least 6-8days to determine the quality and dose of vaccine. In this study, 74 freeze-dried PPR vaccine batches were tested simultaneously by both virus titration and PPR sandwich ELISA (S-ELISA) to correlate the titre of the vaccine virus with reactivity in S-ELISA. It was found that the vaccine batches with titre more than 10(3)TCID(50)/ml gave positive results in S-ELISA and correlated well with the virus titre of the freeze-dried vaccines. The correlation coefficient between the virus titration and S-ELISA reactivity was estimated as 0.96, indicating a high correlation between the two parameters based on 74 batches of freeze-dried PPR vaccine. The vaccine batches with titres of 3.0, 4.3, 4.5, 5.0, 6.5 and 7.0 had shown a positive reaction when tested in two-fold dilutions in S-ELISA at 1, 5, 6, 7, 8 and 9log2 titres, respectively. The test vaccine batches were found to be negative in S-ELISA when the titre of the vaccine was less than 10(3)TCID50/ml, suggesting that the vaccine could not be passed for field use. It is concluded that S-ELISA could be a preliminary tool useful for the quality control of PPR vaccine as it is rapid and easy to perform when compared to virus titration.     

Cytokines expression profile and kinetics of Peste des petits ruminants virus antigen and antibody in infected and vaccinated goats

The present study deals with the co-ordination of cytokine (IL-4 and IFN-γ) expression and kinetics of peste des petits ruminants (PPR) virus antigen and antibody in PPRV infected and vaccinated goats. The infected animals exhibited mixed cytokine (both T_H1 and T_H2) responses in the initial phase of the disease. The infected and dead goats had increased IFN-γ response before their death; while IL-4 remained at the base level. The cytokine expression in recovered animals was almost similar to that of vaccinated ones, where a unique biphasic response of IL-4 expression was observed with an up-regulation of IFN-γ on 7^th days post vaccination (dpv). Analysis of PPR virus antigen and antibody kinetics in different components of blood from infected and vaccinated animals revealed that the PPR virus antigen load was highest in plasma followed by serum and blood of the infected animals, whereas vaccinated animals showed only marginal positivity on 9^th dpv. The antibody titer was high in serum followed by plasma and blood in both vaccinated and infected animals. Therefore, it is inferred that the presence of antigen and antibody were significant with the expression of cytokine, and that a decreased response of IL-4 was noticed during intermediate phase of the disease i.e., 7 to 12^th days post infection (dpi). This indicates the ability to mount a functional T_H2 response after 14^th dpi could be a critical determinant in deciding the survival of the PPR infected animal.     

Study on passive immunity: Time of vaccination in kids born to goats vaccinated against Peste des petits ruminants

In this study, the decay of maternal peste des petits ruminants virus (PPRV) antibodies in kids born to goats vaccinated with Asian lineage IV PPR vaccine and the efficacy of passive immunity against PPRV was assessed to determine the appropriate period for vaccination in kids. Serum samples collected from kids born to vaccinated, unvaccinated and infected goats at different time intervals were tested by PPR competitive ELISA and serum neutralization test (SNT). Maternal antibodies in kids were detectable up to 6 months with a decline trend from the third month onwards and receded below the protective level by the fourth month. The kid with an SN titre of 1:8 at the time of immunization showed significant PPRV specific antibody response (percentage inhibition of 76; SN titers >1:16), when tested on 21 day post-vaccination and was completely protected from infection upon virulent PPRV challenge. Similarly, the kid with 1:8 SN titers was completely protected from PPR infection on active challenge. Therefore, PPR vaccination is recommended in kids, aged 4 months and born to immunized or exposed goats. This could be a suitable period to avoid window of susceptibility in kids to PPRV and the effort to eliminate PPR infection from susceptible populations.     

A virosomal malaria peptide vaccine elicits a long-lasting sporozoite-inhibitory antibody response in a phase 1a clinical trial

Objectives

Peptides delivered on the surface of influenza virosomes have been shown to induce solid humoral immune responses in experimental animals. High titers of peptide-specific antibodies were also induced in a phase 1a clinical trial in volunteers immunized with virosomal formulations of two peptides derived from the circumsporozoite protein (CSP) and the apical membrane antigen 1 (AMA-1) of Plasmodium falciparum. The main objective of this study was to perform a detailed immunological and functional analysis of the CSP-specific antibodies elicited in this phase 1a trial.

Methodology/Principal Findings

46 healthy malaria-naïve adults were immunized with virosomal formulations of two peptide-phosphatidylethanolamine conjugates, one derived from the NANP repeat region of P. falciparum CSP (designated UK-39) the other from P. falciparum AMA-1 (designated AMA49-C1). The two antigens were delivered in two different concentrations, alone and in combination. One group was immunized with empty virosomes as control. In this report we show a detailed analysis of the antibody response against UK-39. Three vaccinations with a 10 µg dose of UK-39 induced high titers of sporozoite-binding antibodies in all volunteers. This IgG response was affinity maturated and long-lived. Co-administration of UK-39 and AMA49-C1 loaded virosomes did not interfere with the immunogenicity of UK-39. Purified total IgG from UK-39 immunized volunteers inhibited sporozoite migration and invasion of hepatocytes in vitro. Sporozoite inhibition closely correlated with titers measured in immunogenicity assays.

Conclusions

Virosomal delivery of a short, conformationally constrained peptide derived from P. falciparum CSP induced a long-lived parasite-inhibitory antibody response in humans. Combination with a second virosomally-formulated peptide derived from P. falciparum AMA-1 did not interfere with the immunogenicity of either peptide, demonstrating the potential of influenza virosomes as a versatile, human-compatible antigen delivery platform for the development of multivalent subunit vaccines.

Trial Registration

ClinicalTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00400101","term_id":"NCT00400101"}}NCT00400101     

A novel recombinant multisubunit vaccine against Chlamydia

The administration of an efficacious vaccine is the most effective long-term measure to control the oculogenital infections caused by Chlamydia trachomatis in humans. Chlamydia genome sequencing has identified a number of potential vaccine candidates, and the current challenge is to develop an effective delivery vehicle for induction of a high level of mucosal T and complementary B cell responses. Vibrio cholerae ghosts (VCG) are nontoxic, effective delivery vehicles with potent adjuvant properties, and are capable of inducing both T cell and Ab responses in mucosal tissues. We investigated the hypothesis that rVCG could serve as effective delivery vehicles for single or multiple subunit chlamydial vaccines to induce a high level of protective immunity. rVCG-expressing chlamydial outer membrane proteins were produced by a two-step genetic process, involving cloning of Omp genes in V. cholerae, followed by gene E-mediated lysis of the cells. The immunogenicity and vaccine efficacy of rVCG-expressing single and multiple subunits were compared. Immunologic analysis indicated that i.m. immunization of mice with either vaccine construct induced a strong mucosal and systemic specific Th1 response against the whole chlamydial organism. However, there was an immunogenic advantage associated with the multiple subunit vaccine that induced a higher frequency of Th1 cells and a relatively greater ability to confer protective immunity, compared with the single subunit construct. These results support the operational theory that the ability of a vaccine to confer protective immunity against Chlamydia is a function of the level of Th1 response elicited.     

A novel STING agonist-adjuvanted pan-sarbecovirus vaccine elicits potent and durable neutralizing antibody and T cell responses in mice,rabbits and NHPs

The emergence of SARS-CoV-2 variants and potentially other highly pathogenic sarbecoviruses in the future highlights the need for pan-sarbecovirus vaccines.Here...     

Effects of dietary chromium supplementation on glucose tolerance and primary antibody response against peste des petits ruminants in dwarf Bengal goats ( Capra hircus)

An experiment was conducted to exploit the immune-modulation effect of trivalent chromium (Cr) for augmenting immunity against peste des petits ruminants (PPR) in dwarf black Bengal goats (Capra hircus). The goats (n = 6 per treatment group) either received a basal diet devoid of supplemental Cr (control) or were supplemented with 0.5 mg Cr as chromic chloride (+Cr) for 60 days. Live weight gain and feed conversion efficiency improved (P < 0.05) in the +Cr dietary group. Supplemental Cr did not affect the total number of monocytes, eosinophils and basophils (P > 0.1) although total leukocytes increased (P < 0.05) and the ratio of neutrophils to lymphocytes narrowed down (P < 0.05) in the +Cr dietary group. The effect of Cr supplementation on variables of the intravenous glucose tolerance test (IVGTT) was inconclusive. Compared to the control group, the basal concentration of glucose (P < 0.05) and insulin (P < 0.001) was higher, clearance rate was slower (P < 0.05) and serum half-life was greater (P < 0.05) in the +Cr dietary group during the IVGTT. Over the duration of the experiment, serum concentration of insulin increased (P < 0.001) and that of cortisol decreased (P < 0.01) in the +Cr group, which also showed a relatively higher primary antibody (Ab) response against PPR on days 10 (P < 0.01) and 20 (P < 0.05) post-vaccination. In conclusion, the experiment indicated that supplementation of Cr as CrCl3, in the diet of non-stressed goats, may improve primary Ab response against PPR and help confer an augmented immunity to the disease besides promoting growth and feed conversion.     

Polyvalent envelope glycoprotein vaccine elicits a broader neutralizing antibody response but is unable to provide sterilizing protection against heterologous Simian/human immunodeficiency virus infection in pigtailed macaques

The great difficulty in eliciting broadly cross-reactive neutralizing antibodies (NAbs) against human immunodeficiency virus type 1 (HIV-1) isolates has been attributed to several intrinsic properties of their viral envelope glycoprotein, including its complex quaternary structure, extensive glycosylation, and marked genetic variability. Most previously evaluated vaccine candidates have utilized envelope glycoprotein from a single virus isolate. Here we compare the breadth of NAb and protective immune response following vaccination of pigtailed macaques with envelope protein(s) derived from either single or multiple viral isolates. Animals were challenged with Simian/human immunodeficiency virus strain DH12 (SHIV(DH12)) following priming with recombinant vaccinia virus(es) expressing gp160(s) and boosting with gp120 protein(s) from (i) LAI, RF, 89.6, AD8, and Bal (Polyvalent); (ii) LAI, RF, 89.6, AD8, Bal, and DH12 (Polyvalent-DH12); (iii) 89.6 (Monovalent-89.6); and (iv) DH12 (Monovalent-DH12). Animals in the two polyvalent vaccine groups developed NAbs against more HIV-1 isolates than those in the two monovalent vaccine groups (P = 0.0054). However, the increased breadth of response was directed almost entirely against the vaccine strains. Resistance to SHIV(DH12) strongly correlated with the level of NAbs directed against the virus on the day of challenge (P = 0.0008). Accordingly, the animals in the Monovalent-DH12 and Polyvalent-DH12 vaccine groups were more resistant to the SHIV(DH12) challenge than the macaques immunized with preparations lacking a DH12 component (viz. Polyvalent and Monovalent-89.6) (P = 0.039). Despite the absence of any detectable NAb, animals in the Polyvalent vaccine group, but not those immunized with Monovalent-89.6, exhibited markedly lower levels of plasma virus than those in the control group, suggesting a superior cell-mediated immune response induced by the polyvalent vaccine.     

A recombinant mimetics of the HIV-1 gp41 prehairpin fusion intermediate fused with human IgG Fc fragment elicits neutralizing antibody response in the vaccinated mice

HIV-1 gp41 prehairpin fusion intermediate (PFI) composed of three N-terminal heptad repeats (NHR) plays a crucial role in viral fusion and entry and represents an attractive target for anti-HIV therapeutics (e.g., enfuvirtide) and vaccines. In present study, we constructed and expressed two recombinant gp41 PFI mimetics, designated N46Fd and N46FdFc. N46Fd consists of N46 (residues 536-581) in gp41 NHR and foldon (Fd), a trimerization motif. N46FdFc is composed of N46Fd fused with human IgG Fc fragment as an immunoenhancer. We immunized mice with N46 peptide, N46Fd and N46FdFc, respectively, and found that only N46FdFc elicited neutralizing antibody response in mice against infection by HIV-1 strains IIIB (clade B, X4), 92US657 (clade B, R5), and 94UG103 (clade A, X4R5). Anti-N46FdFc antibodies inhibited PIE7 binding to PFI, blocked gp41 six-helix bundle formation, and suppressed HIV-1 mediated cell-cell fusion. These findings provide an important clue for developing recombinant gp41 PFI mimetics-based HIV vaccines.     

DNA vaccination with the Hantaan virus M gene protects Hamsters against three of four HFRS hantaviruses and elicits a high-titer neutralizing antibody response in Rhesus monkeys

Four hantaviruses-Hantaan virus (HTNV), Seoul virus (SEOV), Dobrava virus (DOBV) and Puumala virus-are known to cause hemorrhagic fever with renal syndrome (HFRS) in Europe and Asia. HTNV causes the most severe form of HFRS (5 to 15% case-fatality rate) and afflicts tens of thousands of people annually. Previously, we demonstrated that DNA vaccination with a plasmid expressing the SEOV M gene elicited neutralizing antibodies and protected hamsters against infection with SEOV and HTNV. Here, we report the construction and evaluation of a DNA vaccine that expresses the HTNV M gene products, G1 and G2. DNA vaccination of hamsters with the HTNV M gene conferred sterile protection against infection with HTNV, SEOV, and DOBV. DNA vaccination of rhesus monkeys with either the SEOV or HTNV M gene elicited high levels of neutralizing antibodies. These are the first immunogenicity data for hantavirus DNA vaccines in nonhuman primates. Because a neutralizing antibody response is considered a surrogate marker for protective immunity in humans, our protection data in hamsters combined with the immunogenicity data in monkeys suggest that hantavirus M gene-based DNA vaccines could protect humans against the most severe forms of HFRS.     

A triclade DNA vaccine designed on the basis of a comprehensive serologic study elicits neutralizing antibody responses against all clades and subclades of highly pathogenic avian influenza H5N1 viruses

Because of their rapid evolution, genetic diversity, broad host range, ongoing circulation in birds, and potential human-to-human transmission, H5N1 influenza viruses remain a major global health concern. Their high degree of genetic diversity also poses enormous burdens and uncertainties in developing effective vaccines. To overcome this, we took a new approach, i.e., the development of immunogens based on a comprehensive serologic study. We constructed DNA plasmids encoding codon-optimized hemagglutinin (HA) from 17 representative strains covering all reported clades and subclades of highly pathogenic avian influenza H5N1 viruses. Using DNA plasmids, we generated the corresponding H5N1 pseudotypes and immune sera. We performed an across-the-board pseudotype-based neutralization assay and determined antigenic clusters by cartography. We then designed a triclade DNA vaccine and evaluated its immunogenicity and protection in mice. We report here that (sub)clades 0, 1, 3, 4, 5, 6, 7.1, and 9 were grouped into antigenic cluster 1, (sub)clades 2.1.3.2, 2.3.4, 2.4, 2.5, and 8 were grouped into another antigenic cluster, with subclade 2.2.1 loosely connected to it, and each of subclades 2.3.2.1 and 7.2 was by itself. Importantly, the triclade DNA vaccine encoding HAs of (sub)clades 0, 2.3.2.1, and 7.2 elicited broadly neutralizing antibody responses against all H5 clades and subclades and protected mice against high-lethal-dose heterologous H5N1 challenge. Thus, we conclude that broadly neutralizing antibodies against all H5 clades and subclades can indeed be elicited with immunogens on the basis of a comprehensive serologic study. Further evaluation and optimization of such an approach in ferrets and in humans is warranted.     

Examination of epithelial tissue cytokine response to natural peste des petits ruminants virus (PPRV) infection in sheep and goats by immunohistochemistry

In this study, we aimed to evaluate expression of IL-4, IL-10, TNF-α, IFN-γ and iNOS in lingual, buccal mucosa and lung epithelial tissue using immunoperoxidase technique and to compare with the tissues of control animals. The tissues used in the study were collected from 17 PPRV-affected and 5 healthy sheep and goats. In PPRV positive animals, the lungs, lingual and buccal mucosa had significantly higher iNOS, IFN-γ and TNF-α expressions compared to control group animals. There was no significant difference between PPRV positive and control groups for IL-4 and IL-10 expressions of epithelial tissues. In conclusion, the epithelial tissues infected by PPRV showed significant iNOS, IFN-γ and TNF-α expressions and they might play an important role in the initiation and regulation of cytokine response, as they take place in the first host barrier to be in contact with PPRV. It is suggested that the more epithelial damage produced by PPRV the more cytokine response may result in the infected epithelial cells. The first demonstration of iNOS expression and epithelial cytokine response to PPRV in natural cases is important because it may contribute to an early initiation of systemic immunity against PPRV infection, in addition to direct elimination of the virus during the initial epithelial phase of the infection.     

A prime-boost vaccination strategy using attenuated Salmonella typhimurium and a replication-deficient recombinant adenovirus vector elicits protective immunity against human respiratory syncytial virus

Human respiratory syncytial virus (RSV), for which no clinically approved vaccine is available yet, is globally a serious pediatric pathogen of the lower respiratory tract. Several approaches have been used to develop vaccines against RSV, but none of these have been approved for use in humans. An efficient vaccine-enhancing strategy for RSV is still urgently needed. We found previously that oral SL7207/pcDNA3.1/F and intranasal FGAd/F were able to induce an effective protective immune response against RSV. The heterologous prime-boost immunization regime has been reported recently to be an efficient vaccine-enhancing strategy. Therefore, we investigated the ability of an oral SL7207/pcDNA3.1/F prime and intranasal (i.n.) FGAd/F boost regimen to generate immune responses to RSV. The SL7207/pcDNA3.1/F prime-FGAd/F boost regimen generated stronger RSV-specific humoral and mucosal immune responses in BALB/c mice than the oral SL7207/pcDNA3.1/F regimen alone, and stronger specific cellular immune responses than the i.n. FGAd/F regimen alone. Histopathological analysis showed an increased efficacy against RSV challenge by the heterologous prime-boost regimen. These results suggest that such a heterologous prime-boost strategy can enhance the efficacy of either the SL7207 or the FGAd vector regimen in generating immune responses in BALB/c mice.     

A comparative seroepidemiologic study of the neutralizing antibody against the virulent standard strains and the Sabin vaccine strains of poliovirus among healthy Japanese

The neutralizing antibody of 160 serum specimens collected in 1978 from healthy residents in five prefectures in Japan was titrated against both the virulent standard strains and the Sabin vaccine strains of three types of poliovirus. Antibody-positive rates with both strains of respective types at a level of 1:4 were comparable in all three types of poliovirus. However, the geometric mean titers (GMTs) obtained against both strains showed statistically significant difference depending on the age-cohort's previous history of exposure to the wild or the vaccine strains of polioviruses: the younger age cohorts showed higher GMTs to the Sabin strains, while adults responded higher to the virulent standard strains. The difference was most pronounced in type 1.     

Recombinant, live-attenuated tetravalent dengue virus vaccine formulations induce a balanced, broad, and protective neutralizing antibody response against each of the four serotypes in rhesus monkeys

Three tetravalent vaccine (TV) formulations of previously described monovalent dengue (DEN) virus vaccine candidates were compared to a tetravalent formulation of wild-type DEN viruses (T-wt) for replication in SCID mice transplanted with human liver cells (SCID-HuH-7) or for replication and immunogenicity in rhesus monkeys. TV-1 consists of recombinant DEN1, -2, -3, and -4, each with a 30-nucleotide deletion in the 3' untranslated region (Delta30). TV-2 consists of rDEN1Delta30, rDEN4Delta30, and two antigenic chimeric viruses, rDEN2/4Delta30 and rDEN3/4Delta30, both also bearing the Delta30 mutation. TV-3 consists of rDEN1Delta30, rDEN2Delta30, rDEN4Delta30, and a 10-fold higher dose of rDEN3/4Delta30. TV-1 and TV-2 were attenuated in SCID-HuH-7 mice with minimal interference in replication among the virus components. TV-1, -2, and -3 were attenuated in rhesus monkeys as measured by duration and peak of viremia. Each monkey immunized with TV-1 and TV-3 seroconverted to the four DEN components by day 28 with neutralization titers ranging from 1:52 to 1:273 and 1:59 to 1:144 for TV-1 and TV-3, respectively. TV-2 induced low antibody titers to DEN2 and DEN3, but a booster immunization after 4 months increased the neutralizing antibody titers to greater than 1:100 against each serotype and elicited broad neutralizing activity against 19 of 20 DEN subtypes. A single dose of TV-2 induced protection against wild-type DEN1, DEN3, and DEN4 challenge, but not DEN2. However, two doses of TV-2 or TV-3 induced protection against DEN2 challenge. Two tetravalent formulations, TV-2 and TV-3, possess properties of a successful DEN vaccine and can be considered for evaluation in clinical trials.