Investigation of antigen specific lymphocyte responses in healthy horses vaccinated with an inactivated West Nile virus vaccine

Davis, Elizabeth G.; Zhang, Kun; Tuttle, John R.; Hankins, Kevin; Wilkerson, Melinda J.

doi:10.1016/j.vetimm.2008.08.007

Cited by 13 publications

(10 citation statements)

References 27 publications

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“…The applied immunization scheme resulted in development of adequate B-cell memory, as indicated by the strong responses observed after annual boosters and natural infections. The results regarding these responses are supported by a previous study in which significant NAb titer increases (log 2 5-fold) against both lineages is described, and the titers achieved were well above their peaks observed after the initial vaccination (55) (54), indicating that, besides humoral immunity, the vaccine induces T-cell responses, which might also contribute to the cross-protection of the naturally infected horses.…”

Section: Discussionsupporting

confidence: 84%

“…Previous studies with Equip WNV have indicated that immunized horses maintained NAb titers of Ն1: 100 against lineage 1 strains for 5 to 7 months, as determined by plaque reduction neutralization tests (PRNT) (53). In another study, it was shown that neutralizing responses were maintained for 6 months after vaccination of immunologically naive horses (54). In a more recent study, it has been demonstrated that NAbs may be detected in samples obtained 1 year after the primary vaccination course in naive horses, although a decline in neutralizing titers was observed (55).…”

Section: Discussionmentioning

confidence: 99%

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Evaluation of Cross-Protection of a Lineage 1 West Nile Virus Inactivated Vaccine against Natural Infections from a Virulent Lineage 2 Strain in Horses, under Field Conditions

Chaintoutis

Diakakis

Papanastassopoulou

et al. 2015

Clin Vaccine Immunol

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Although experimental data regarding cross-protection of horse West Nile virus (WNV) vaccines against lineage 2 infections exist, the cross-protective efficacy of these vaccines under field conditions has not been demonstrated. This study was conducted to evaluate the capability of an inactivated lineage 1 vaccine (Equip WNV) to protect against natural infections from the Nea Santa-Greece-2010 lineage 2 strain. In total, 185 WNV-seronegative horses in Thessaloniki, Greece, were selected during 2 consecutive years (2011 and 2012); 140 were immunized, and 45 were used as controls. Horses were examined for signs compatible with WNV infection. Neutralizing antibody titers against the Greek strain and the PaAn001/France lineage 1 strain were determined in immunized horses. WNV circulation was detected during both years in the study area. It was estimated that 37% and 27% of the horses were infected during 2011 and 2012, respectively. Three control animals developed clinical signs, and the WNV diagnosis was confirmed. Signs related to WNV infection were not observed in the vaccinated animals. The nonvaccinated animals had a 7.58% ؎ 1.82% higher chance of exhibiting signs than immunized animals (P < 0.05). Neutralizing antibodies raised against both strains in all immunized horses were detectable 1 month after the initial vaccination course. The cross-protective capacity of the lowest titer (1:40) was evident in 19 animals which were subsequently infected and did not exhibit signs. Neutralizing antibodies were detectable until the annual booster, when strong anamnestic responses were observed (geometrical mean titer ratio [GMTR] for lineage 1 of 30.2; GMTR for lineage 2 of 27.5). The results indicate that Equip WNV is capable of inducing cross-protection against natural infections from a virulent lineage 2 WNV strain in horses. West Nile virus (WNV) is a single-stranded RNA virus within the Japanese encephalitis virus serocomplex, which belongs to the genus Flavivirus (family Flaviviridae) (1). WNV is maintained in nature by enzootic transmission cycles between certain bird species and ornithophilic mosquitoes (2). Mosquitoes mainly belonging to the genus Culex can also act as bridge vectors, transmitting the virus to other animal species, including incidental hosts (3-6). Humans and horses are regarded as incidental (deadend) hosts, as the virus titer developed in their blood is generally too low to infect mosquitoes (7). Nevertheless, WNV infection in susceptible hosts may eventually cause neurological disease (8). Regarding horses, the reported clinical signs may vary, and these include fever, paraparesis or tetraparesis, and ataxia, recumbency, and behavioral changes, while in many clinically affected horses muscle fasciculation and tremors are also present. It is expected that deaths will occur in a small percentage of the affected animals (9-13).Phylogenetic analyses of WNV strains isolated worldwide have resulted in the identification of 8 genetic lineages of the virus so far (14). Until 2004, only viral strains...

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Section: Discussionsupporting

confidence: 84%

Section: Discussionmentioning

confidence: 99%

Evaluation of Cross-Protection of a Lineage 1 West Nile Virus Inactivated Vaccine against Natural Infections from a Virulent Lineage 2 Strain in Horses, under Field Conditions

Chaintoutis

Diakakis

Papanastassopoulou

et al. 2015

Clin Vaccine Immunol

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“…In a serologic surveillance programme in a WNV free area, positive ELISA results should always be confirmed by using plaque reduction neutralization tests (PRNT) which allows to identify the flavivirus causing the seroconversion (El Garch et al 2008, Davis et al 2008 The PRNT is considered the most specific test for the arthropod-borne flaviviruses and can be used to help distinguish false-positive results in an IgM antibody-capture enzyme-linked immunosorbent assay or other assays (for example, indirect immunofluorescence and hemagglutination inhibition tests). The plaque-reduction neutralization test may also help distinguish serologic cross-reactions among the flaviviruses (CDC website).…”

Section: Discussionmentioning

confidence: 99%

“…However, these authors stated that current anti-WNV vaccination protocols have minimal effect on testing serum when using MAC-ELISA (IgM Capture ELISA). Davis et al (2008) noted seroconversion of IgG and IgM after a WNV vaccination protocol. In that study, serologic evidence of enhanced antigen-specific IgM expression was evident after completion of the vaccination protocol and was maintained for 14 weeks.…”

Section: Introductionmentioning

confidence: 99%

West Nile Virus Vaccination in Horses – IgM and IgG responses after injection in different muscles

Jonquière¹,

Heijden²,

Maanen³

et al. 2011

PHK

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West Nile Virus (WNV) may cause significant morbidity and mortality in birds, humans and horses. WNV is not (yet) present in the Netherlands, but it is steadily approaching from south-eastern Europe. Recently, a WNV-vaccine (Duvaxyn ® -WNV) became available in Europe. It is claimed that vaccination results not or only infrequently in an IgM response making it possible to differentiate acutely-infected horses from vaccinated horses by using an IgM-based ELISA. The aims of the study were to investigate the supposition that vaccination does not result in IgM production, to evaluate whether different intramuscular injection sites influence the immunological responses and whether any local or systemic adverse reactions would occur. Twenty horses and ponies, 3 to 21 years old, were divided into four groups and horses of each group were vaccinated twice (day 0 and 21) at different intramuscular sites (neck, pectoral muscles, rump and thigh). Weekly blood samples were collected over a period of 42 days and tested for Flavivirus IgM antibodies using a WNV-IgM ELISA and for Flavivirus Ig antibodies using a WNV blocking ELISA. None of the horses tested positive for WNV antibodies prior to vaccination. All horses showed a clear Ig (total antibody) response to the WNV vaccination, but in two horses this response was limited. Surprisingly, ten horses also gave a (limited) positive IgM response. This suggests that an IgM capture ELISA will not distinguish horses with an acute WNV infections from recently vaccinated horses with certainty. The location of the intramuscular injections had no significant effect on the immunogenic response. No systemic reactions were encountered nor were there local reactions at any of the injection sites.

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“…The first equine vaccine, introduced in 2002, comprised formalin-inactivated WNV adjuvanted with MetaStim adjuvant (West Nile Innovator; Pfizer) (8). Horses that received two doses and that were challenged 1 year postvaccination showed markedly reduced WNV viremia, affecting just 5% of immunized horses but 82% of controls (9).…”

mentioning

confidence: 99%

An Inactivated Cell Culture Japanese Encephalitis Vaccine (JE-ADVAX) Formulated with Delta Inulin Adjuvant Provides Robust Heterologous Protection against West Nile Encephalitis via Cross-Protective Memory B Cells and Neutralizing Antibody

Petrovsky

Larena

Siddharthan

et al. 2013

J Virol

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e West Nile virus (WNV), currently the cause of a serious U.S. epidemic, is a mosquito-borne flavivirus and member of the Japanese encephalitis (JE) serocomplex. There is currently no approved human WNV vaccine, and treatment options remain limited, resulting in significant mortality and morbidity from human infection. Given the availability of approved human JE vaccines, this study asked whether the JE-ADVAX vaccine, which contains an inactivated cell culture JE virus antigen formulated with Advax delta inulin adjuvant, could provide heterologous protection against WNV infection in wild-type and ␤2-microglobulindeficient (␤2m ؊/؊ ) murine models. Mice immunized twice or even once with JE-ADVAX were protected against lethal WNV challenge even when mice had low or absent serum cross-neutralizing WNV titers prior to challenge. Similarly, ␤2m ؊/؊ mice immunized with JE-ADVAX were protected against lethal WNV challenge in the absence of CD8 ؉ T cells and prechallenge WNV antibody titers. Protection against WNV could be adoptively transferred to naive mice by memory B cells from JE-ADVAX-immunized animals. Hence, in addition to increasing serum cross-neutralizing antibody titers, JE-ADVAX induced a memory Bcell population able to provide heterologous protection against WNV challenge. Heterologous protection was reduced when JE vaccine antigen was administered alone without Advax, confirming the importance of the adjuvant to induction of cross-protective immunity. In the absence of an approved human WNV vaccine, JE-ADVAX could provide an alternative approach for control of a major human WNV epidemic.

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Investigation of antigen specific lymphocyte responses in healthy horses vaccinated with an inactivated West Nile virus vaccine

Cited by 13 publications

References 27 publications

Evaluation of Cross-Protection of a Lineage 1 West Nile Virus Inactivated Vaccine against Natural Infections from a Virulent Lineage 2 Strain in Horses, under Field Conditions

Evaluation of Cross-Protection of a Lineage 1 West Nile Virus Inactivated Vaccine against Natural Infections from a Virulent Lineage 2 Strain in Horses, under Field Conditions

West Nile Virus Vaccination in Horses – IgM and IgG responses after injection in different muscles

An Inactivated Cell Culture Japanese Encephalitis Vaccine (JE-ADVAX) Formulated with Delta Inulin Adjuvant Provides Robust Heterologous Protection against West Nile Encephalitis via Cross-Protective Memory B Cells and Neutralizing Antibody

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