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.     

Self-Assembly and Release of Peste des Petits Ruminants Virus-Like Particles in an Insect Cell-Baculovirus System and Their Immunogenicity in Mice and Goats

Peste des petits ruminants (PPR) is an acute, febrile, viral disease of small ruminants that has a significant economic impact. For many viral diseases, vaccination with virus-like particles (VLPs) has shown considerable promise as a prophylactic approach; however, the processes of assembly and release of peste des petits ruminants virus (PPRV) VLPs are not well characterized, and their immunogenicity in the host is unknown. In this study, VLPs of PPRV were generated in a baculovirus system through simultaneous expression of PPRV matrix (M) protein and hemaglutin in (H) or fusion (F) protein. The released VLPs showed morphology similar to that of the native virus particles. Subcutaneous injection of these VLPs (PPRV-H, PPRV-F) into mice and goats elicited PPRV-specific IgG production, increased the levels of virus neutralizing antibodies, and promoted lymphocyte proliferation. Without adjuvants, the immune response induced by the PPRV-H VLPs was comparable to that obtained using equivalent amounts of PPRV vaccine. Thus, our results demonstrated that VLPs containing PPRV M protein and H or F protein are potential “differentiating infected from vaccinated animals” (DIVA) vaccine candidates for the surveillance and eradication of PPR.     

Complement-mediated, infection-enhancing antibodies in plasma from vaccinated macaques before and after inoculation with live simian immunodeficiency virus.

Rhesus monkeys vaccinated against infection with simian immunodeficiency virus (SIV) were examined, in retrospect, for the presence of infection-enhancing antibodies and possible consequences associated with the presence of these antibodies. At the time of experimental inoculation with live virus, complement-mediated, infection-enhancing antibodies were detected in plasma specimens from six of six animals vaccinated with detergent-inactivated whole virus, from nine of nine animals vaccinated with Formalin-inactivated whole virus, and from seven of eight animals immunized with two SIV subunit preparations. The presence of infection-enhancing antibodies at the time of viral challenge gave no indication of predicting vaccine success or failure. After live-virus challenge, titers of infection-enhancing antibodies, like enzyme-linked immunosorbent assay titers, increased in unprotected animals and decreased or became undetectable in animals protected by vaccination. Thus, vaccine protection against SIV infection can still be achieved in the presence of detectable complement-mediated, infection-enhancing antibodies.     

MVA recombinants expressing the fusion and hemagglutinin genes of PPRV protects goats against virulent challenge

Peste des Petits Ruminants (PPR) is a highly contagious animal disease caused by the Peste des Petits Ruminants virus (PPRV) belonging to the genus morbillivirus and family Paramyxoviridae. The disease results in high morbidity and mortality in goats, sheep and in some small wild ruminants. The presence of large number of small ruminants reared in endemic areas makes PPR a notorious disease threatening the livelihood of poor farmers. Conventional vaccination using a live, attenuated vaccine gives adequate protection but cannot be used in case of eradication of the disease due to difficulty in differentiation of infected animals from the vaccinated ones.     

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.     

Vaccination with Recombinant Adenoviruses Expressing the Peste des Petits Ruminants Virus F or H Proteins Overcomes Viral Immunosuppression and Induces Protective Immunity against PPRV Challenge in Sheep

Peste des petits ruminants (PPR) is a highly contagious disease of small ruminants caused by the Morbillivirus peste des petits ruminants virus (PPRV). Two recombinant replication-defective human adenoviruses serotype 5 (Ad5) expressing either the highly immunogenic fusion protein (F) or hemagglutinin protein (H) from PPRV were used to vaccinate sheep by intramuscular inoculation. Both recombinant adenovirus vaccines elicited PPRV-specific B- and T-cell responses. Thus, neutralizing antibodies were detected in sera from immunized sheep. In addition, we detected a significant antigen specific T-cell response in vaccinated sheep against two different PPRV strains, indicating that the vaccine induced heterologous T cell responses. Importantly, no clinical signs and undetectable virus shedding were observed after virulent PPRV challenge in vaccinated sheep. These vaccines also overcame the T cell immunosuppression induced by PPRV in control animals. The results indicate that these adenovirus constructs could be a promising alternative to current vaccine strategies for the development of PPRV DIVA vaccines.     

Peste des Petits Ruminants Virus Tissue Tropism and Pathogenesis in Sheep and Goats following Experimental Infection

Peste des petits ruminants (PPR) is a viral disease which primarily affects small ruminants, causing significant economic losses for the livestock industry in developing countries. It is endemic in Saharan and sub-Saharan Africa, the Middle East and the Indian sub-continent. The primary hosts for peste des petits ruminants virus (PPRV) are goats and sheep; however recent models studying the pathology, disease progression and viremia of PPRV have focused primarily on goat models. This study evaluates the tissue tropism and pathogenesis of PPR following experimental infection of sheep and goats using a quantitative time-course study. Upon infection with a virulent strain of PPRV, both sheep and goats developed clinical signs and lesions typical of PPR, although sheep displayed milder clinical disease compared to goats. Tissue tropism of PPRV was evaluated by real-time RT-PCR and immunohistochemistry. Lymph nodes, lymphoid tissue and digestive tract organs were the predominant sites of virus replication. The results presented in this study provide models for the comparative evaluation of PPRV pathogenesis and tissue tropism in both sheep and goats. These models are suitable for the establishment of experimental parameters necessary for the evaluation of vaccines, as well as further studies into PPRV-host interactions.     

Congenital neosporosis in goats from the State of Minas Gerais, Brazil

Congenital Neospora caninum infection was diagnosed in two Saanen goat kids from two distinct herds with a history of abortion and weak newborn goat kids in the Southern region of the State of Minas Gerais, Brazil. The first kid was weak at birth, had difficulty to rise and was unable to nurse. Gross lesions of porencephaly and hydrocephalus ex vacuo were seen. Multifocal necrosis, gliosis and non-supurative encephalitis were observed in the brain. Several parasitic cysts with a thick wall that reacted strongly only with polyclonal antiserum to Neospora caninum were seen in the cerebral cortex, brain stem and cerebellum. The second kid was born from a Neospora caninum seropositive mother that aborted in the last pregnancy. It was born without clinical signs. The diagnosis of neosporosis was based on antibody titer of 1:800 to N. caninum by indirect fluorescence antibody test obtained from blood collected before the goat kid ingested the colostrum and Neospora caninum DNA was detected by polymerase chain reaction and sequenced from placenta. This is the first report of neosporosis in goats in the southeast region of Brazil.     

Birthdate, mass and survival in mountain goat kids: effects of maternal characteristics and forage quality

In temperate environments, early-born ungulates may enjoy a longer growth period before winter, and so attain a higher body mass and an increased probability of survival compared to late-born ones. We assessed the effects of maternal characteristics, forage quality and population density on kid birthdate, mass and survival in a population of marked mountain goats (Oreamnos americanus) in Alberta. The duration and timing of the birth season were similar in all years. Births were highly synchronised: 80% of kids were born within 2 weeks of the first birth. Maternal age, maternal social rank and density did not affect kid birthdate or mass. Previous breeding experience was not related to kid birthdate, but kids born to pluriparous mothers were heavier during summer than kids born to primiparous mothers. Male and female kids had similar mass and accumulated mass linearly during summer. Early-born kids were heavier than late-born kids. Faecal crude protein (FCP) in late spring and maternal mass were positively related to kid mass. Survival to weaning appeared higher for males (90%) than for females (78%), but survival to 1 year was 65% for both sexes. FCP in late spring, density, birthdate and mass did not affect kid survival to weaning in either sex. Survival to 1 year increased with FCP in late spring for females, but not for males. Survival to 1 year was independent of birthdate for both sexes, but heavy females survived better than light ones. Multiple logistic regression revealed a positive effect of mass on survival to 1 year when the sexes were pooled. Our results suggest that mountain goats are constrained to give birth in a short birth season synchronised with forage productivity.     

Corynebacterium Pseudotuberculosis Infection in Goats VI.

Twelve kids, 5 1/2 months old, were inoculated intravenously with about 1 million colony forming units of a Corynebacterium pseudotuberculosis strain isolated from goat. Nine of the animals had antibodies against the organism in the bacterial agglutination test and/or the hemolysis inhibition test before they were inoculated. Four kids developed acute toxemia and died 2–5 days after the inoculation. Three of these animals were negative in both the bacterial agglutination test and the hemolysis inhibition test, while the fourth was positive in the bacterial agglutination test only. Post mortem examination revealed severe icterus, anemia, hemoglobinuria and acute pneumonia with microabscess formation in 3 of the kids that died. Eight animals, all with antibodies against C. pseudotuberculosis, developed acute illness but survived the inoculation. These animals were sacrificed and examined post mortem 1 month after the experimental infection, and abscesses were demonstrated in internal organs in all cases. It is concluded that intravenous inoculation with C. pseudotuberculosis is not a suitable challenge system to study the prophylactic efficacy of vaccines against caseous lymphadenitis in goats.     

Humoral response and protection from experimental challenge following vaccination of raccoon pups with a modified-live canine distemper virus vaccine.

Eight 8-wk-old raccoon pups (Procyon lotor) with maternal canine distemper virus (CDV) neutralizing antibodies (NAb) and 24 8-wk-old seronegative pups were administered a commercial modified-live CDV vaccine (Galaxy, D, Solvay Animal Health, Inc., Kitchener, Ontario, Canada). All 24 seronegative raccoons had detectable serum CDV NAb titers 14 days after the initial dose. Titers rose to maximum levels 4 wk post-vaccination. Mean titers for groups of vaccinated seronegative pups were maintained between 1:256 and 1:2,048 for the remainder of the 3 mo observation period. Geometric means of the serum CDV NAb titer of eight seronegative pups given a single vaccine dose at 8 wk of age did not differ significantly from those of eight pups that were given serial doses at 8, 12, and 16 wk of age, or from those of eight pups vaccinated once at 16 wk of age. Seven unvaccinated 8-wk-old raccoon pups used as controls remained seronegative throughout the trial. Seven out of eight 8-wk-old pups with maternal antibodies, vaccinated at 8, 12, and 16 wk of age, failed to develop a rise in their CDV NAb titers until at least 18 wk of age, 2 wk after the third vaccination. Titers in eight unvaccinated raccoons with maternal antibodies declined steadily to undetectable levels at 20 wk of age. A half-life of 10.55 days was calculated for maternally-derived CDV NAb in raccoon pups. Sixteen vaccinated raccoons were protected from clinical disease following experimental oronasal challenge with a virulent raccoon strain of CDV, 13 to 23 wk after vaccination. Serum CDV NAb titers at the time of challenge ranged from 1:12 to 1:384 and increased during the period of observation. Three of four unvaccinated seronegative raccoons used as controls failed to mount any detectable CDV NAb and were euthanatized after developing clinical signs of canine distemper 26, 29, and 30 days post-challenge (PC). Necropsies confirmed the diagnosis. The fourth control raccoon exhibited transient equivocal clinical signs, mounted a sluggish humoral response, but was clinically normal when euthanatized 42 days PC. In this raccoon, there was focal non-suppurative encephalitis with intranuclear inclusion bodies typical of CDV infection.     

Lack of risk of transmission of caprine arthritis-encephalitis virus (CAEV) after an appropriate embryo transfer procedure

The aim of this study was to demonstrate that embryo transfer can be used to produce CAEV-free kids from CAEV-infected biological mothers when appropriate procedure is implemented. Twenty-eight goats that had tested positive for CAEV using PCR on vaginal secretions were used as embryo donors. Embryos with intact-ZP were selected and washed 10 times; they were then frozen and used for transfer into CAEV-free recipient goats. Nineteen of the 49 recipient goats gave birth, producing a total of 23 kids. Three blood samples were taken from each recipient goat, 10 days before, during, and 10 days after parturition; these were tested for CAEV antibodies using ELISA and for CAEV proviral DNA using PCR. The mothers were then euthanized. Tissue samples were taken from the lungs, udder, and retromammary and prescapular lymph nodes. The kids were separated from their mothers at birth. Seven of them died. At 4 months of age, 16 kids were subjected to drug-induced immunosuppression. Blood samples were taken every month from birth to 4 months of age; samples were then taken on days 15, 21, and 28 after the start of the immunosuppressive treatment. The kids were then euthanized and tissue samples taken from the carpal synovial membrane, lung tissue, prescapular lymph nodes, inguinal and retromammary lymph nodes, and uterus. All samples from the 19 recipient goats and 23 kids were found to be negative for CAEV antibodies and/or CAEV proviral DNA. Under acute conditions for infection this study clearly demonstrates that embryo transfer can be safely used to produce CAEV-free neonates from infected CAEV donors.     

Fasciola hepatica: an antigen fraction derived from newly excysted juveniles, containing an immunoreactive 32-kDa protein, induces strong protective immunity in rats

Crude antigens of adult Fasciola hepatica and of newly excysted juveniles (NEJ) and a low-molecular-weight fraction of antigen from NEJs were tested for inducing protective immunity in rats. Two routes of vaccination were applied. The results showed that intraperitoneal vaccination induced significantly better protection (P <0.05) than intramuscular vaccination. Intraperitoneal vaccination with antigens from NEJs induced more effective protection: after challenge infection, rats that were so vaccinated had 92.6% (+/-2.5% SEM) fewer parasites in their liver and 57.3% (+/-13.3% SEM) fewer parasites penetrating the gut wall than control rats. Rats that were vaccinated with a low-molecular-weight fraction of antigen from NEJs were also highly protected against a challenge. F. hepatica antigens that are immunoreactive were identified on immunoblots, using sera collected from highly protected rats that had been vaccinated with NEJ antigens and also sera from cattle and rats that were experimentally infected with F. hepatica. The low-molecular-weight fraction of antigen from NEJs contained an immunodominant 32-kDa protein that was recognized by serum antibodies of vaccinated rats and immune cattle. This 32-kDa protein was not detected in partially purified antigens from adult flukes. We conclude that antigens of NEJs of F. hepatica, when injected intraperitoneally in rats, are highly protective. In particular, the 32-kDa protein contained in these antigens may be highly valuable for the development of an effective vaccine against F. hepatica.     

Protective immunity in macaques vaccinated with a modified vaccinia virus Ankara-based measles virus vaccine in the presence of passively acquired antibodies

Recombinant modified vaccinia virus Ankara (MVA), encoding the measles virus (MV) fusion (F) and hemagglutinin (H) (MVA-FH) glycoproteins, was evaluated in an MV vaccination-challenge model with macaques. Animals were vaccinated twice in the absence or presence of passively transferred MV-neutralizing macaque antibodies and challenged 1 year later intratracheally with wild-type MV. After the second vaccination with MVA-FH, all the animals developed MV-neutralizing antibodies and MV-specific T-cell responses. Although MVA-FH was slightly less effective in inducing MV-neutralizing antibodies in the absence of passively transferred antibodies than the currently used live attenuated vaccine, it proved to be more effective in the presence of such antibodies. All vaccinated animals were effectively protected from the challenge infection. These data suggest that MVA-FH should be further tested as an alternative to the current vaccine for infants with maternally acquired MV-neutralizing antibodies and for adults with waning vaccine-induced immunity.     

Vaccination of vampire bats using recombinant vaccinia-rabies virus

Adult vampire bats (Desmodus rotundus) were vaccinated by intramuscular, scarification, oral, or aerosol routes (n = 8 in each group) using a vaccinia-rabies glycoprotein recombinant virus. Sera were obtained before and 30 days after vaccination. All animals were then challenged intramuscularly with a lethal dose of rabies virus. Neutralizing antirabies antibodies were measured by rapid fluorescent focus inhibition test (RFFIT). Seroconversion was observed with each of the routes employed, but some aerosol and orally vaccinated animals failed to seroconvert. The highest antibody titers were observed in animals vaccinated by intramuscular and scarification routes. All animals vaccinated by intramuscular, scarification, and oral routes survived the viral challenge, but one of eight vampire bats receiving aerosol vaccination succumbed to the challenge. Of 31 surviving vaccinated and challenged animals, nine lacked detectable antirabies antibodies by RFFIT (five orally and four aerosol immunized animals). In contrast, nine of 10 non-vaccinated control bats succumbed to viral challenge. The surviving control bat had antiviral antibodies 90 days after viral challenge. These results suggest that the recombinant vaccine is an adequate and safe immunogen for bats by all routes tested.     

Use of simian immunodeficiency virus for vaccine research

Rhesus monkeys were immunized with purified, disrupted, noninfectious simian immunodeficiency virus (SIV) in adjuvant induced SIV neutralizing antibodies. Two of six previously vaccinated macaques were protected against infection when challenged with 200-1,000 animal infectious doses of uncloned, pathogenic SIV and both have remained free of signs of virus infection for 19 and 30 months. Prior vaccination appeared to be of benefit in decreasing the virus load and in delaying the onset of AIDS in animals that became infected. Nonetheless, two of four previously vaccinated monkeys that became infected following challenge eventually developed AIDS and died 505 and 538 days after infection. Thus, for a vaccine to be truly effective against AIDS, it may have to protect absolutely against initial infection.     

禽呼肠孤病毒感染对鸡法氏囊及免疫应答的影响

研究LY株禽呼肠孤病毒(ARV)感染1日龄SPF鸡后对法氏囊发育影响,对传染性法氏囊病毒(IBDV)、禽流感病毒(AIV)、新城疫病毒(NDV)疫苗免疫诱发的抗体的影响,及对强毒株IBDV致病作用的影响。结果表明,LY株ARV感染1日龄SPF鸡可引起法氏囊萎缩和部分淋巴细胞减少,但对增重及AIV和NDV疫苗免疫后抗体滴度却没有显著影响。ARV感染可降低弱毒IBDV疫苗免疫后的抗体反应,但对随后IBDV强毒株攻毒的抵抗力却与对照鸡无显著差异。经IBDV弱毒疫苗免疫后,再接种强毒株IBDV,不会引起死亡,但却仍能显著抑制对AIV、NDV疫苗免疫后的抗体滴度。然而,对于1~7日龄经ARV感染的鸡,IBDV强毒的这种免疫抑制作用又显著低于未经ARV感染的对照鸡。     

Serological study and risk factor analysis on Peste des Petits Ruminants in sheep in Bangladesh

A cross-sectional study was conducted to determine the seroprevalence of the Peste des Petits Ruminant (PPR) virus (PPRV) in sheep populations and to determine the potential epidemiological risk factors associated with this infection. Between October 2014 and March 2017, 2420 sheep serum samples were collected from ten selected PPR outbreak-prone districts in Bangladesh. The collected sera were analysed by competitive enzyme-linked immunosorbent assay (cELISA) test to detect antibodies against PPR. A previously designed disease report form was used to gather data on important epidemiological risk factors, and a risk analysis was performed to ascertain their association with PPRV infection. By cELISA, 44.3 % (95 % confidence interval:42.4–46.4 %) of sheep sera were positive for PPRV antibodies against PPR. In univariate analysis, the Bagerhat district had significantly higher seropositivity (54.1 %, 156/288) than other districts. Moreover, significantly higher (p < 0.05) seropositivity was found in the Jamuna River Basin (49.1 %, 217/442) compared to other ecological zones, in crossbreeds (60 %; 600/1000) related to native sheep, in males (69.8 %, 289/414) associated with females, in imported sheep (74.3 %, 223/300) compared to other sources, and in winter (57.2 %, 527/920) than in other seasons. In the multivariate logistic regression model, six possible risk factors were identified: study location, ecological zone, breed, sex, source, and season. The high seroprevalence of PPRV is significantly associated with several risk factors, suggesting that PPR is epizootic throughout the country.     

Differential effects of undernutrition during pregnancy on the behaviour of does and their kids at parturition and on the establishment of mutual recognition

We investigated whether undernutrition during the second half of pregnancy impaired the behaviour of does and their kids at parturition and early mutual recognition. Twenty-two control and 22 underfed mixed-breed, multiparous dairy goats were used, together with their respective kids (control, n = 31: nine singles, 16 twins and six triplets; underfed, n = 32: 11 singles, 18 twins and three triplets). Undernutrition involved limiting protein and energy intake at 70% of the nutritional requirements for maintenance and foetal growth from day 70 of pregnancy until birth. The behaviour of mothers and their two first-born kids was observed for 90 min from the birth of each kid. Maternal olfactory recognition of the kid was assessed at 4 h post partum by testing selective nursing behaviour. Non-olfactory recognition was assessed at 8 h in a two-choice test excluding olfactory cues. In kids, preference for the mother was assessed in a two-choice test at either 12 or 24 h post partum. Bodyweight of does and kids were lower in the underfed group up to 2 weeks post partum. At parturition, licking, maternal bleating frequency and latency to nursing did not differ between nutritional groups. Control kids were faster than underfed kids to stand, search for and reach the udder, but underfed kids bleated more and tended to spend more time at the udder. Both control and underfed does accepted their own kid and rejected the alien in the selectivity test at 4 h. In contrast, at 8 h post partum, only control goats showed a significant preference for their own kid in the non-olfactory recognition test. Both control and underfed kids showed a preference for their own mother at 12 and 24 h and undernutrition during pregnancy had little influence on the performance of kids. However, 12 h-old underfed kids tended to be less active than control kids and visited their own mothers less than control kids. There were no significant correlations between the behaviour of the mother or of the kid at parturition and their performance in the discrimination tests. Overall, undernutrition in the second half of pregnancy appears to be more detrimental for the behaviour of the mother than for the kid. Furthermore, it has more impact on the establishment of maternal non-olfactory recognition than on maternal care at parturition or the establishment of maternal selectivity.     

Protection of Rabbits from Viral Challenge by Gene Gun-Based Intracutaneous Vaccination with a Combination of Cottontail Rabbit Papillomavirus E1, E2, E6, and E7 Genes

In this study, cottontail rabbit papillomavirus infection of domestic rabbits was used as an animal model to develop papillomavirus early gene-based vaccines. Groups of rabbits were intracutaneously vaccinated with single papillomavirus early genes E1, E2, E6, and E7 or with a combination of these four genes. Only a fraction of rabbits were protected from subsequent viral challenge when vaccinated with the E1 or E6 gene. Viral tumor growth in those rabbits vaccinated with the E1 or E2 gene was suppressed compared to that in controls. In contrast, seven of nine rabbits vaccinated with the combination of the E1, E2, E6, and E7 genes were completely protected against viral challenge. These data indicated that intracutaneous genetic vaccination with the combination of the E1, E2, E6, and E7 genes can be an effective strategy for immunoprophylaxis of papillomavirus infection.