AB4 Vaccine

BACKGROUND: Extensive investigation has been undertaken about the utilization of saponin adjuvants in vaccines intended for veterinary and human applications. AB4 is the main constituent of the traditional Chinese medicine, Pulsatilla chinensis (Bunge) Regel, and has immunomodulatory activity. However, there is a paucity of reports on AB4 as a potential adjuvant. PURPOSE: The objective of this work was to clarify the adjuvant role of AB4 and the molecular mechanisms that underlie its immunomodulatory actions...

Equid herpesvirus-1 (EHV-1) causes respiratory and neurological disease and late gestation abortion in pregnant mares. Current vaccines contain either inactivated or live EHV-1, but fail to provide complete clinical or virological protection, namely prevention of nasopharyngeal shedding and cell-associated viraemia. Thus, the development of novel products, such as modified live virus (MLV) vaccines which stimulate virus-specific, humoral and cell mediated immune responses more effectively remains a priority...

Equine Herpesvirus type 1 (EHV-1) outbreaks continue to occur despite widely used vaccination. Therefore, development of EHV-1 vaccines providing improved immunity and protection is ongoing. Here, an open reading frame 2 deletion mutant of the neuropathogenic EHV-1 strain Ab4 (Ab4ΔORF2) was tested as a vaccine candidate. Three groups of horses (n=8 each) were infected intranasally with Ab4ΔORF2, the parent Ab4 virus, or kept as non-infected controls. Horses infected with Ab4ΔORF2 had reduced fever and nasal virus shedding compared to those infected with Ab4 but mounted similar adaptive immunity dominated by antibody responses...

Equid herpesvirus-1 (EHV-1) outbreaks continue despite widely used vaccination. We demonstrated previously that an ORF1/ORF71 gene deletion mutant of the EHV-1 strain Ab4 (Ab4ΔORF1/71) is less virulent than its parent Ab4 virus. Here, we describe the Ab4 challenge infection evaluating protection induced by the Ab4ΔORF1/71 vaccine candidate. Susceptible control horses developed respiratory disease, fever, nasal shedding, and viremia. Full protection after challenge infection was observed in 5/5 previously Ab4 infected horses and 3/5 Ab4ΔORF1/71 horses...

The equine herpesvirus type 1 (EHV-1) ORF1 and ORF71 genes have immune modulatory effects in vitro. Experimental infection of horses using virus mutants with multiple deletions including ORF1 and ORF71 showed promise as vaccine candidates against EHV-1. Here, the combined effects of ORF1 and ORF71 deletions from the neuropathogenic EHV-1 strain Ab4 on clinical disease and host immune response were further explored. Three groups of EHV-1 naïve horses were experimentally infected with the ORF1/71 gene deletion mutant (Ab4ΔORF1/71), the parent Ab4 strain, or remained uninfected...

A mouse anti-anti-anti-idiotypic (Id) IgM monoclonal antibody (mAb K20, Ab4), functionally mimicking a Wyckerhamomyces anomalus (Pichia anomala) killer toxin (KT) characterized by fungicidal activity against yeasts presenting specific cell wall receptors (KTR) mainly constituted by β-1,3-glucan, was produced from animals presenting anti-KT Abs (Ab3) following immunization with a rat IgM anti-Id KT-like mAb (mAb K10, Ab2). MAb K10 was produced by immunization with a KT-neutralizing mAb (mAb KT4, Ab1) bearing the internal image of KTR...

Equine herpesvirus-1 (EHV-1) continues to cause both sporadic and epidemic abortions despite extensive vaccination. Lack of progress in the development of protective vaccines may be hindered by the lack of equine abortion models that employ contemporary EHV-1 strains. The objective of our experiments was to compare a contemporary EHV-1 strain with a previously described challenge strain, and to quantify EHV-1 loads in various maternal and fetal tissues. Infection experiments were performed in two groups of 7 pregnant pony mares at 270-290 days of gestation with a contemporary EHV-1 strain (University of Findlay 2003 isolate - OH03) or an EHV-1 strain isolated over 30 years ago, and previously described in abortion models (Ab4)...

In this study, experimental canarypox virus (ALVAC) and plasmid DNA recombinant vaccines expressing the gB, gC and gD glycoproteins of EHV-1 were assessed for their ability to protect conventional ponies against a respiratory challenge with EHV-1. In addition, potential means of enhancing serological responses in horses to ALVAC and DNA vaccination were explored. These included co-administration of the antigen with conventional adjuvants, complexation with DMRIE-DOPE and co-expression of the antigen along with equine GM-CSF...

In general, vaccines containing inactivated equine herpesvirus-1 (EHV-1) fail to prevent abortion in pregnant mares following infection with a virulent strain of EHV-1. We have tested the hypothesis that resistance to EHV-1-induced abortion in pregnant mares is associated with high frequencies of EHV-1 specific, major histocompatibility complex (MHC) class I-restricted, cytotoxic T lymphocytes (CTL) in the circulation. To test this theory, three groups of pregnant mares were assembled with varying backgrounds of infection or vaccination in an attempt to mimic the immune status of the general population...

In this study, a serotype-specific monoclonal antibody (mAb), D(2) 16-1 (Ab4), against dengue virus type 2 (DEN-2) was generated. The specificity of Ab4, which recognized DEN-2 non-structural protein 1, was determined by ELISA, immunofluorescence and immunoblotting analyses. The serotype-specific B-cell epitope of Ab4 was identified further from a random phage-displayed peptide library; selected phage clones reacted specifically with Ab4 and did not react with other mAbs. Immunopositive phage clones displayed a consensus motif, His-Arg/Lys-Leu/Ile, and a synthetic peptide corresponding to the phage-displayed peptide bound specifically to Ab4...

Basic in vitro characteristics of high and low virulence isolates of equine herpesviruses-1 and -4 were investigated with particular reference made to the Ab4 and V592 isolates of EHV-1 as both have distinct endotheliotropism and clinical outcomes in pony challenge studies. Additionally, some EHV-4 isolates that showed variations in clinical outcome were included in some experiments. The aim of the study was to identify an in vitro characteristic that would differentiate strains of known virulence. Such a system could then be applied to vaccine and virulence studies as an effective screening tool...

Pregnant mares and young foals were vaccinated with Duvaxyn EHV1,4, an inactivated and adjuvanted vaccine containing both the EHV-1 and 4 antigens. SN and CF antibody titres were induced two weeks after first vaccination. Antibody levels were boosted after second vaccination, however they never reached the levels induced after virus challenge. Young foals were challenged with virulent EHV-1 and EHV-4 field viruses. Pregnant mares were challenged with the highly abortigenic EHV-1 strain Ab4. Vaccinated animals showed a clear reduction in clinical signs and virus excretion compared to unvaccinated control animals...

Experiments were conducted to analyze the equine herpesvirus 1 (EHV-1) gene 68 product which is encoded by the EHV-1 Us2 homolog. An antiserum directed against the amino-terminal 206 amino acids of the EHV-1 Us2 protein specifically detected a protein with an Mr of 34,000 in cells infected with EHV-1 strain RacL11. EHV-1 strain Ab4 encodes a 44,000-Mr Us2 protein, whereas vaccine strain RacH, a high-passage derivative of RacL11, encodes a 31,000-Mr Us2 polypeptide. Irrespective of its size, the Us2 protein was incorporated into virions...

Equine herpesvirus-1 (EHV-1) causes rhinopneumonitis, abortion and CNS disorders in horses. Using intranasal inoculation, the mouse model of this disease mimics the major pathogenic and clinical features of the equine disease. The aim of this study was to investigate whether murine dendritic cells (DC) can be infected with EHV-1 and whether they can be used as cellular vaccines for the induction of prophylactic anti-EHV-1 immunity. It was found that the DC lines FSDC, D2SC1, 18 (all H-2d) and 80/1 (H-2k), when incubated with the Ab4 strain of EHV-1, do not change their morphology and phenotype but sustain virus replication and induce proliferation of naive, syngeneic T cells...

The equine herpesvirus type-1 modified live-vaccine strain RacH (256th passage on porcine embryonic kidney cells) was investigated by restriction-enzyme analysis and compared to representative plaque isolates of the 12th passage (RacL11, RacL22) and 185th passage (RacM24, RacM36). The restriction patterns of all Rac plaque isolates differed compared with reference strain Ab4. The left UL terminus was shortened by 0.1 kbp and a missing BamHI site led to the fusion of the f and t fragments. In some Rac derivatives, losses of restriction sites without deletions were observed: 1...

We have amplified, cloned and sequenced the gene encoding the thymidine kinase (TK) of a wild-type strain (Ab4) of equine herpesvirus-1 (EHV-1) and two mutants with defective TK activity isolated for resistance to penciclovir (PCV). One of the mutants, PR1, has suffered a 879-bp deletion which reduces the size of TK to 180 bp. The other mutant, PR3, has an adenine to cytosine mutation resulting in a Lys38-->Thr change. This mutation modifies the amino acid sequence of a domain involved in binding ATP, leading to non-detectable enzymatic activity...

Twelve adult ponies and 2 conventional foals were exposed to 10(6.6) TCID50 of Equid herpesvirus-1 (EHV-1), strain Ab4 and samples of respiratory tract tissues were recovered. Infectious virus in tissue homogenates was detected using susceptible cell monolayers and expression of viral antigens was monitored using indirect immunoperoxidase histochemistry of paraffin sections. The results illustrated the rapid dissemination of EHV-1 throughout the respiratory tract, with early replication in the lungs one day after exposure...