Comparative immunogenicity of two peste des petitis ruminants (PPR) vaccines in South Indian sheep and goats under field conditions

Investigation of the effect of mutual vaccination with pest des petits ruminants and polyvalent foot and mouth disease vaccines on the immune response of sheep

Background

Pest des petits ruminants (PPRs) and foot and mouth disease (FMD) are two viral infectious diseases affecting sheep dramatically causing great economic losses. Therefore, attention should be directed toward their control, especially through the application of well-designed vaccination schedules with specific potent vaccines.

Aim

Determination of the possibility of sheep vaccination with PPR and FMD vaccines in a mutual schedule.

Methods

Different groups of sheep have vaccinated with live attenuated PPR vaccine and inactivated polyvalent FMD vaccine in a mutual manner (one before the other at weekly intervals or simultaneously) followed by monitoring of the induced immunity to both vaccines using serum neutralization test (SNT) and enzyme linked immune sorbent assay (ELISA).

Results

SNT and ELISA revealed that there was no antagonizing effect of any vaccine on the immune response to the mutual vaccination of sheep to the other where the obtained antibody titers in single vaccinated sheep groups were similar to those in the simultaneous vaccinated group.

Conclusion

Simultaneous vaccination of sheep with PPR and polyvalent FMD vaccine is of applicable benefit saving time, effort, and stress factors on the animals.

Systems Biology behind Immunoprotection of Both Sheep and Goats after Sungri/96 PPRV Vaccination

Immune response is a highly coordinated cascade involving all the subsets of peripheral blood mononuclear cells (PBMCs). In this study, RNA sequencing (RNA-Seq) analysis of PBMC subsets was done to delineate the systems biology behind immune protection of the vaccine in sheep and goats. The PBMC subsets studied were CD4⁺, CD8⁺, CD14⁺, CD21⁺, and CD335⁺ cells from day 0 and day 5 of sheep and goats vaccinated with Sungri/96 peste des petits ruminants virus. Assessment of the immune response processes enriched by the differentially expressed genes (DEGs) in all the subsets suggested a strong dysregulation toward the development of early inflammatory microenvironment, which is very much required for differentiation of monocytes to macrophages, and activation as well as the migration of dendritic cells into the draining lymph nodes. The protein-protein interaction networks among the antiviral molecules (IFIT3, ISG15, MX1, MX2, RSAD2, ISG20, IFIT5, and IFIT1) and common DEGs across PBMC subsets in both species identified ISG15 to be a ubiquitous hub that helps in orchestrating antiviral host response against peste des petits ruminants virus (PPRV). IRF7 was found to be the key master regulator activated in most of the subsets in sheep and goats. Most of the pathways were found to be inactivated in B lymphocytes of both the species, indicating that 5 days postvaccination (dpv) is too early a time point for the B lymphocytes to react. The cell-mediated immune response and humoral immune response pathways were found more enriched in goats than in sheep. Although animals from both species survived the challenge, a contrast in pathway activation was observed in CD335⁺ cells.

IMPORTANCE Peste des petits ruminants (PPR) by PPR virus (PPRV) is an World Organisation for Animal Health (OIE)-listed acute, contagious transboundary viral disease of small ruminants. The attenuated Sungri/96 PPRV vaccine used all over India against this PPR provides long-lasting robust innate and adaptive immune response. The early antiviral response was found mediated through type I interferon-independent interferon-stimulated gene (ISG) expression. However, systems biology behind this immune response is unknown. In this study, in vivo transcriptome profiling of PBMC subsets (CD4⁺, CD8⁺, CD14⁺, CD21⁺, and CD335⁺) in vaccinated goats and sheep (at 5 days postvaccination) was done to understand this systems biology. Though there are a few differences in the systems biology across cells (specially the NK cells) between sheep and goats, the coordinated response that is inclusive of all the cell subsets was found to be toward the induction of a strong innate immune response, which is needed for an appropriate adaptive immune response.

Field evaluation and confirmation of acute peste des petits ruminant outbreak in a flock of West African dwarf goats in Ibadan, Nigeria

This study utilised epidemiological, haematological, pathological findings and serological detection of specific antibodies to evaluate and confirm a peste des petit ruminants (PPR) outbreak in a herd of West African dwarf (WAD) goats in Ibadan, Nigeria. The morbidity and mortality rates post exposure (PE) were 96% and 60% respectively. Laboratory analyses revealed significant differences (P < 0.05) in mean values of the haematological and serum biochemical indices between the PE and control groups. The PE group experienced a significant (P < 0.05) increase in white blood cell (WBC), lymphocyte and monocytes after 10 days PE; the drop in glucose and high levels of alkaline phosphatase (ALP) and aspartate amino transferase (AST) indicated liver damage, while increased serum creatinine, blood urea nitrogen (BUN) and uric acid arose from kidney impairment. The electrolyte imbalance (potassium, sodium and chloride ions) resulting from the symptomatic diarrhea affected the functionality of the Na⁺–K⁺ pump mechanisms, hence pathologic damage to the liver, kidneys, skin, gastrointestinal, respiratory and cardiovascular systems. The competitive enzyme linked immuno-sorbent assay (c-ELISA) detected varying antibody levels in the PPR infected WAD goats; the percent inhibition was highest (P < 0.001) in survivors (70.00 ± 1.73), then in contact group (60.00 ± 2.00), and least in infected (23.33 ± 1.53), which were sero-negative. This study confirmed a PPR outbreak in a WAD goat flock in Ibadan, Nigeria.

Assessment of immune response to a lyophilized peste-des-petits-ruminants virus vaccine in three different breeds of goats

Aim:

Immune response to a lyophilized peste-des-petits-ruminants virus (PPRV) vaccine was evaluated in three different breeds of goats.

Materials and Methods:

Three breeds of goats consisting six number of animals in three groups, i.e., Group A (local Assam hill goat), Group B (cross-bred), and Group C (Beetal goats) were randomly selected for evaluating the immune response to a lyophilized PPRV vaccine.

Results:

A higher rise in the overall mean serum antibody titer was observed in Group A (40.50±3.74) than in Group B (37.58±37.58) and Group C (35.90±3.29) during the study period.

Conclusion:

Initially, a negative PPRV specific serum antibody titer was recorded in all the groups at 0^th day of vaccination. Serum antibody titer in the vaccinated goats started rising gradually from the 14^th day post vaccination. Later higher rise in the overall mean serum antibody titer in Group A (local Assam hill goat) lead to the conclusion that higher serum antibody titer in local non-descript breed might be due to their better adaptation to the environmental condition.

Protective immune response of live attenuated thermo-adapted peste des petits ruminants vaccine in goats

Virulent isolate of peste des petits ruminants virus (PPRV) of Indian origin (PPRV Jhansi 2003) initially adapted in Vero cells was further propagated in thermo-adapted (Ta) Vero cells grown at 40 °C for attaining thermo-adaption and attenuation of virus for development of Ta vaccine against PPR in goats and sheep. The virus was attenuated up to 50 passages in Ta Vero cells, at which, the virus was found sterile, innocuous in mice and guinea pigs and safe in seronegative goats and sheep. The developed vaccine was tested for its immunogenicity in goats and sheep by subcutaneous inoculation of 100 TCID50 (0.1 field dose), 10(3) TCID50 (one field dose) and 10(5) TCID50 (100 field doses) of the attenuated virus along with controls as per OIE described protocols for PPR vaccine testing and were assessed for PPRV-specific antibodies 7-28 days post vaccination (dpv) by PPR competitive ELISA and serum neutralization tests. The PPRV antibodies were detected in all immunized goats and sheep and goats were protective when challenged with virulent PPRV at 28th dpv along with controls for potency testing of the vaccine. The attenuated vaccine did not induce any adverse reaction at high dose (10(5) TCID50) in goats and sheep and provided complete protection even at low dose (10(2) TCID50) in goats when challenged with virulent virus. There was no shedding and horizontal transmission of the attenuated virus to in-contact controls. The results indicate that the developed PPR Ta attenuated virus is innocuous, safe, immunogenic and potent or efficacious vaccine candidate alternative to the existing vaccines for the protection of goats and sheep against PPR in the tropical countries like India.