Passive Immunity In Foals Born From Mares Vaccinated Against Theileira .
Ciência Rural,Maria,v.52:8,e20210182,2022 against Theileira equi and StreptococcusPassiveSantaimmunityin foalsborn frommares vaccinatedequi subspecies SNe 1678-4596MICROBIOLOGYPassive immunity in foals born from mares vaccinated against Theileira equi andStreptococcus equi subspecies equiAlice Corrêa Santos1Carlos Eduardo Wayne Nogueira21Vitória MüllerRafaela Pinto de Souza2Ruth Patten2Leandro Quintana Nizoli3Fábio Pereira Leivas Leite1*Centro de Desenvolvimento Tecnológico, Faculdade de Biotecnologia, Universidade Federal de Pelotas (UFPel), 96010-610, Pelotas, RS,Brasil. E-mail: fleivasleite@gmail.com. *Corresponding autor.2Departamento de Clínicas Veterinária, Faculdade de Medicina Veterinária, Universidade Federal de Pelotas (UFPel), Pelotas, RS, Brasil3Departamento de Veterinária Preventiva, Faculdade de Medicina Veterinária. Universidade Federal de Pelotas(UFPel), Pelotas, RS, Brasil1ABSTRACT: The aims of this study were: 1) determine total specific IgG and subisotypes in serum and colostrum of pregnant mares vaccinatedagainst Theileria equi and Streptococcus equi subspecies equi; 2) determine total specific IgG and subisotypes in foals born from these mares.In mares, the highest total serum IgG value for T. equi was at 335 days of gestation declining 30 days postpartum, while for S. equi was at 328days of gestation remaining high up to 30 days postpartum. Transfer of passive immunity against both antigens was observed with specificIgG values in colostrum and foals’ serum proportional to mares’ values. The most detected specific IgG subisotypes were IgG3/5 and IgG4/7for both antigens. Foals born from mares immunized with T. equi kept maternal IgG values until 2 months of age, while those born from maresimmunized with S. equi kept maternal IgG values until 3-4 months of age. These results suggest that foals should be vaccinated after this period.Key words: equine, vaccine, passive immunity, IgG subisotypes.Imunidade passiva em potros provenientes de éguas vacinadas contra Theileira equi eStreptococcus equi subspécie equiRESUMO: Os objetivos deste estudo foram: 1) determinar IgG total específica e seus subisotipos no soro e colostro de éguas vacinadascontra Theileria equi e Streptococcus equi subspécie equi; 2) determinar IgG total específica e seus subisotipos em potros provenientesdessas éguas. Em éguas vacinadas contra T. equi, o maior nível sérico de IgG total específico ocorreu aos 335 dias de gestação, decaindo 30dias pós parto, enquanto nas vacinadas contra S. equi, ocorreu aos 328 dias de gestação e manteve-se pelo mesmo período. A avaliação deIgG total específica no colostro de éguas vacinadas demonstrou níveis de IgG proporcionais aos títulos do soro materno. Os isotipos de IgGmais detectados foram IgG3/5 e IgG4/7 para ambos antígenos avaliados. Potros provenientes de éguas vacinadas com antígeno de T. equimantiveram os níveis de IgG específica até dois meses de idade, enquanto potros provenientes de éguas vacinadas com antígeno de S. equimantiveram por três a quatro meses, sugerindo que esse seja o período ideal para início do esquema vacinal em potros.Palavras-chave: equinos, vacina, imunidade passiva, isotipos de IgG.INTRODUCTIONTheileria equi is a hemoparasite andone of the etiologic agents of equine piroplasmosis(KNOWLES Jr., 1996), an endemic disease in Brazilthat causes severe hemolytic anemia (WISE et al.,2014). The bacteria Streptococcus equi subspeciesequi is a microorganism responsible for causingstrangles, a disease with high morbidity and oneof the most common diseases of the equine upperrespiratory tract (MORAES et al., 2009).ImmunocompetenthorsesproduceIgG1 and IgG4/7 during acute T. equi infections.These antibody subisotypes are directly related toReceived 03.08.21controlling infection (CUNHA et al., 2006), whileIgG3/5 generally only appears during chronicinfections (MEALEY et al., 2012). Antibodyproduction in animals infected by S. equi is importantfor controlling infection and for establishingimmunologic memory (FLOCK et al., 2004). Theantibody subisotype IgG4/7 is the most frequentlyobserved subisotype in the serum of S. equi infectedanimals, especially during the acute phase, followedby IgG1 (SHEORAN et al., 1997).Understanding passive transfer is key toestablishing vaccination protocols for foals (PERKINS& WAGNER, 2015; BORDIN et al., 2014; WILSONet al., 2001). Foals respond inefficiently to most ofthe vaccines designed for use in adult, indicating aApproved 08.24.21Returned by the author 11.10.21CR-2021-0182.R2Juliana Felipetto CargneluttiEditors: Rudi WeiblenCiência Rural, v.52, n.8, 2022.
2Santos et al.difficulty in developing protective vaccines in younghorses. The development of a vaccine formulationfor this age range requires the understanding ofthe interaction between passive immunity and thedevelopment of active immunity by the foal, whichis still developing its immune system (PERKINS &WAGNER, 2015).Given the clinical and epidemiologicalimportance of T. equi and S. equi, as well as therelevance of studying the immune response to thesepathogens for vaccine development and controlstrategy improvement, the aims of the presentstudy were to: 1) determine total specific IgG andsubisotypes in serum and colostrum of pregnant maresvaccinated against T. equi and S. equi; 2) determinetotal specific vaccine antigens IgG and subisotypes inserum of foals born from vaccinated mares.MATERIALS AND METHODSAnimalsThirty two mare/foal pairs from the Centrode Ensino e Experimentação em Equinocultura daPalma (CEEEP), Universidade Federal de Pelotas/RS,Brazil. All mares were mixed breed, multiparous andaged between 10 and 15 years old. After pregnancyconfirmation, gestations were monitored monthly byultrasonography. Animals were kept on pasture (Loliummultiflorum) with water ad libitum during the entireexperimental period. At the time of foaling, mares werebrought into sanitized stalls and foalings were monitoredand assisted when needed. Foals were closely monitoredover the first 24 hours of life, received primary care andwere then returned to the paddocks.VaccinesThe recombinant protein EMA-2 wasobtained using the protocol described by VIANNAet al. (2014). Briefly, a partial sequence of EMA-2gene was amplified by PCR using as a template DNAextracted from the blood of an animal experimentallyinfected with the T. equi UFPEL E15 strain. Theamplicon was cloned into pPICZ alphaB (InvitrogenTM,USA), and the resulting plasmid was transformed intoPichia pastoris X33. A Mut colony was selected toperform the expression of the recombinant protein,and the rEMA-2 protein was recognized by antibodiespresent in the serum of naturally infected horses.The vaccine was prepared by adding 200 µg of therecombinant protein to aluminum hydroxide 10% (Al(OH)3, Sigma-Aldrich , Darmstadt, Germany).The S. equi antigen was obtained by usingthe protocol described by RIBAS et al. (2018), inwhich punch of retropharyngeal lymph nodes ofnaturally infected horses were performed and the S.equi isolate was confirmed through culture and PCRidentification. For vaccine preparation, a strain ofS. equi was cultured in Brain Heart Infusion (BHI)(Sigma-Aldrich) with 1% peptone added for 18 hoursat 37 C. The culture was centrifuged at 2150 g in theA-4-44 rotor of a 5804 centrifuge (Eppendorf fromBrazil, São Paulo, Brazil) and the pellet was suspendedin sterile saline. Titration was then performed throughserial dilution and seeding in BHI agar base. In order toprepare the vaccine, a bacterial suspension containing2.5 108 CFU/ml was inactivated in 37% formalin(1:5.000) (Labsynth , São Paulo, Brazil) and adsorbedin 10% Al (OH)3 adjuvant (Sigma-Aldrich ).Mares were assigned randomly to threedifferent groups: 1) Vaccinated Group - T. equi antigen(n 15); 2) Vaccinated Group - S. equi antigen (n 12); 3) Control Group - inoculated with Al(OH)3and PBS (n 5). The vaccination protocol started at300 days of gestation, with a booster vaccination at21 days after the first dose. Clinical parameters suchas heart rate, respiratory rate, capillary perfusiontime, mucosal staining and rectal temperature of themares were evaluated weekly. Blood was collectedby venipuncture of the external jugular vein using 25x 8 gauge needles and tubes without anticoagulant(BD Vacutainer , New Jersey, USA) weekly fromday 300 (first vaccination) until foaling, at the time offoaling and then at 7 and 30 days postpartum in orderto obtain serum. Foals were divided into: 1) Foalsborn from mares included in the Vaccinated Group- T. equi antigen (n 15); 2) Foals born from maresincluded in the Vaccinated Group - S. equi antigen (n 12); 3) Foals born from Control mares - vaccinatedwith Al(OH)3 and PBS (n 5). Blood was collectedfrom foals by venipuncture of the external jugularvein using 25 x 8-gauge needles and tubes withoutanticoagulant (BD Vacutainer , New Jersey, USA).Samples were collected at the time of birth, at 12 hoursand at 7, 15, 30 and 60 days of life. Blood sampleswere centrifuged at 1008 X g in analogical clinicalcentrifuge (Centrilab 80-2B-15ml, São Paulo,Brazil) and serum was stored in 1.5 ml microtubes(Eppendorf , São Paulo, Brazil) at -20 C until furtheranalysis. Mares had 2 ml of colostrum collectedmanually immediately after parturition. Colostrumwas stored in 1.5 ml microtubes (Eppendorf , SãoPaulo, Brazil) at -20 C until further analysis.Dynamics of serum total specific IgG and subisotypesEquine serum and colostrum samples wereanalyzed by indirect enzyme-linked immunosorbentCiência Rural, v.52, n.8, 2022.
Passive immunity in foals born from mares vaccinated against Theileira equi and Streptococcus equi subspecies equi.assay (ELISA) to determine anti-S. equi/ anti-T.equi total IgG. In the samples tested for the T. equiantigen, the protocol described by VIANNA et al.(2014) was used with rEMA-2. Polystyrene platescontaining 96-wells (Nunc-Immuno , VWR ,Barcelona, Spain) were sensitized with 200 ng/wellof rEMA-2 during 18 hours at 4 C. After blockingwith 0.5% milk powder, the sera tested were addedin 1:100 dilution and incubated for 60 minutes at 37 C. The anti-equine conjugated serum was addedin 1:6.000 dilution and incubated for 90 minutes at37 C. Development was accomplished by addingchromogen/substrate citrate/phosphate buffer (TPS),keeping the plates in the dark for 15 minutes. Thereaction was interrupted by adding H2SO4 1Nsolution. Absorbance was measured on a microplatereader (TP-READER - Thermo Plate , Brazil) usinga 492 nm wavelength.For the S. equi antigen, serum andcolostrum from mares and serum from foals wereanalyzed individually by ELISA using the protocoldescribed by RIBAS et al. (2018). Polystyrene platescontaining 96-wells (Nunc-Immuno , VWR ,Barcelona, Spain) were sensitized with 106 CFU/ml of S. equi suspended in carbonate-bicarbonatebuffer for 90 minutes at 37 C. After blocking with0.5% milk powder, the sera tested were added in1:100 dilution and incubated for 60 minutes at 37 C. Rabbit anti-horse IgG peroxidase conjugated(Sigma-Aldrich , Darmstadt, Germany) was addedin 1:6.000 dilution and incubated for 90 minutes at37 C. Development was accomplished by addingchromogen/substrate citrate/phosphate buffer (TPS)and keeping the plates in the dark for 15 minutes.The reaction was interrupted by adding H2SO4 1Nsolution. Absorbance was measured on a microplatereader (TP-READER - Thermo Plate , Brazil) usinga 492 nm wavelength.The positive control for rEMA-2 was asample of serum from a horse naturally infectedwith T. equi, confirmed by immunofluorescence andPCR. The positive control for S. equi was a sampleof serum from a horse naturally infected with S.equi, confirmed through culture and microbialidentification. As a negative control, in both tests, anewborn foal serum collected before the first sucklingwas used at 1:100 dilution. All samples and controlswere tested in duplicate.Immunoglobulin G specific subisotypeswere determined by indirect ELISA assay. Thefollowing subisotypes were tested: IgG1, IgG3/5and IgG4/7 (Sigma-Aldrich , Darmstadt, Germany).A pool of serum from all vaccinated mares (samples3from 300 to 328 days of gestation), pool of colostrumfrom all mares, and a pool of serum from all foalsborn from vaccinated mares (samples from 12 hoursof life, 7 days and 1 month of age) were used in orderto determine IgG subisotypes.In the isotyping of antibodies to T. equiantigen, 96-well polystyrene plates (Nunc-Immuno ,VWR , Barcelona, Spain) were sensitized with200ng/well of rEMA-2 during 18 hours at 4 C. Afterwashes with PBS-T, blocking with milk powderwas performed and sera to be tested were added in1:100 dilution and incubated for 60 minutes at 37 C. Subisotypes were tested in 1:1000 dilution andincubated for 30 minutes at 37 C. After washings,conjugated sera were added: anti-goat for IgG3/5 andanti-mouse for IgG1 and IgG4/7 in 1: 4000 dilutionand incubated for 60 minutes at 37 C. Developmentwas accomplished by adding chromogen/substratecitrate/phosphate buffer (TPS) and keeping theplate in the dark for 15 minutes. The reaction wasinterrupted by the addition of H2SO4 1N. Absorbancewas measured on a microplate reader (TP-READER- Thermo Plate , Brazil) using 492 nm wavelength.A similar protocol was used to determine S.equi antigen-reactive IgG subisotypes, differing onlyin the plate sensitization step. A 96-well polystyreneplate (Nunc-Immuno , VWR , Barcelona,Spain) was sensitized with 106 CFU/ml of S. equicarbonate-bicarbonate buffer for 90 minutes at 37 C.Subsequent steps were the same as those describedfor the T. equi antigen.Statistical analysisThe Shapiro-Wilk test was used to verify datanormality. Data that did not present normal distributionwere transformed into base 10 logarithm. Analysisof variance (ANOVA), and post-hoc comparisonswere carried out by the Tukey test. Significance wasset at P 0.05. The commercial software Statistix10.0 (Statistix, Tallahassee, FL, USA) was used fordata analysis and graphs were developed using thecommercial software GraphPad Prism 5.0 (GraphPadSoftware Inc., San Diego, CA, USA).RESULTSNo adverse effects caused by vaccinationswere observed in the animals included in this study,nor were any cases or outbreaks of these diseasesdiagnosed during the study period. All vaccinatedmares responded to the vaccine with an increaseof total specific IgG, whereas no increase IgG wasobserved in control animals, with levels remainingCiência Rural, v.52, n.8, 2022.
4Santos et al.constant for the whole experimental period. Maresvaccinated against T. equi and S. equi respondedto vaccine antigens, differing statistically from thecontrol group starting from the vaccine boost at 321days of gestation, (P 0.05) (Figure 1).The dynamics of total specific IgG differedamong groups. In the T. equi vaccinated group, thehighest values were observed at 335 days, 14 daysafter the booster vaccination. However, in thosevaccinated against S. equi, for the higher ELISAvalues was observed at 328 days, 7 days after thebooster vaccination. In contrast, no changes inspecific IgG for T. equi and S. equi were observed inthe control group. Total specific IgG values differedin the colostrum collected from mares from both theT. equi vaccinated group and the S. equi vaccinatedgroup, when compared to the mares from the controlgroup (Table 1).In regard to the IgG subisotype profile,IgG3/5 was the most recognized antibody subisotypein mares vaccinated against T. equi and S. equi at 300and 328 days of gestation, followed by IgG4/7. Anincrease in IgG subisotypes was observed in maresvaccinated with T. equi and S. equi antigens afterbooster vaccination (328 days). The most recognizedIgG subisotype in the colostrum of the T. equivaccinated group was the IgG3/5, followed by IgG4/7and IgG1. In mares from the S. equi vaccinatedgroup, there was a significant increase in IgG3/5 andIgG4/7 after vaccination, and these subisotypes werealso identified in the colostrum, while IgG1 was notdetected (Figure 2).At the time of birth (0 hours), no specificT. equi and S. equi IgG were identified in the serumof the foals. However, after colostrum ingestion (12hours), all foals presented specific T. equi and S. equiFigure 1 - Serum dynamics of total specific IgG of vaccinated and control mares and IgG subisotypes invaccinated mares. The data represents the mean ( SE) absorbance. 1a) Total specific IgG in Theileriaequi Vaccinated and Control Group. 1b) Total specific IgG in Streptococcus equi Vaccinated andControl Group. 1c) IgG subisotypes in the Theileria equi Vaccinated Group 1d) IgG subisotypes inthe Streptococcus equi Vaccinated Group. Vaccinations ( ) were performed at 300 and 321 days ofgestation. Asterisks (*) indicate statistical difference among groups (P 0.05).Ciência Rural, v.52, n.8, 2022.
Passive immunity in foals born from mares vaccinated against Theileira equi and Streptococcus equi subspecies equi.Table 1 - Total specific IgG in colostrum of mares vaccinatedagainst Theileria equi, mares vaccinated againstStreptococcus equi and in the colostrum of controlmares.T. equiS. equiVaccinated groupControl group0.83 0.28a0.61 0.2a0.39 0.11b0.50 0.02bP 0.0021P 0.02Footnote: Results are described as Mean SE of absorbance(492nm). Different letters indicate statistical difference amonggroups (P 0.05).IgG levels in serum. Foals born from mares vaccinatedagainst T. equi had IgG OD492nm values of about 3.5times higher than those born from control mares (P 0.05). Foals born from mares vaccinated against S.equi had specific IgG OD492nm values of about two5times higher than those born from control mares (P 0.05). Total specific IgG levels were distinct for T.equi and S. equi vaccines (Figure 2).The observed specific IgG subisotypes incolostrum were very similar to those observed in theserum of foals at 12 hours after birth, and both weresimilar to those identified in the maternal serum at 328days of gestation. This observation suggests that thesesubisotypes were transferred via passive immunity.The IgG3/5 subisotype was predominantin foals born from vaccinated mares. Foals born frommares vaccinated against T. equi showed levels ofthe IgG3/5, IgG1 and IgG4/7 subisotypes. It is worthnoting that the level of IgG3/5 decreased between 7and 30 days postpartum, while the other subisotypesdid not. Foals born from mares vaccinated against S.equi showed levels of IgG3/5 and IgG4/7 and thosesubisotypes followed the same trend observed for theT. equi antigen.Figure 2 - Serum dynamics of total specific IgG in foals born from vaccinated and control mares and serum IgG subisotypes invaccinated foals. The data represents the mean ( SE) absorbance. 2a) Total specific IgG in foals born from Theileriaequi vaccinated mares and foals born from control mares. 2b) Total specific IgG in foals born from Streptococcus equivaccinated mares and foals born from control mares. 2c) IgG subisotypes in foals born from Theileria equi vaccinatedmares. 2d) IgG subisotypes in foals born from Streptococcus equi vaccinated mares. Asterisks (*) indicate statisticaldifference among vaccinated and control groups (P 0.05).Ciência Rural, v.52, n.8, 2022.
6Santos et al.DISCUSSIONIn the first months of life the adaptiveimmune system of the foal is immature, and theirinnate immunity differs from immune mechanismsin the adult horse (PERKINGS & WAGNER,2015). Therefore, protection against pathogens isprovided soon after birth through the ingestion ofimmunoglobulin present in the colostrum.At 21 days after the first vaccination,Theileria equi vaccinated mares presented statisticallyhigher total specific IgG levels compared to thecontrol group. However, at 30 days post parturition(which is about 65 days after the first vaccination), nostatistical difference between vaccinated and controlgroups was found. These results corroborate withthose described by VIANNA et al. (2019), whichdemonstrated maintenance of anti-rEMA-2 vaccineantibodies until approximately 60 days after the firstvaccination in adult horses. Mares vaccinated withthe S. equi antigen showed statistically higher totalspecific IgG levels than those from the control groupeven at 30 days postpartum. Using a similar vaccinefor S. equi, RIBAS et al. (2018) observed a totalspecific IgG presence in vaccinated horses for up to100 days.Foals born from T. equi vaccinated mareshad a significant increase in specific IgG aftercolostrum absorption, approximately 43-times higherthan initial OD492nm values, while foals born fromcontrol mares had an increase of only 6.8 times theinitial OD492nm values. At 7 days after birth, the IgGlevels started to decrease in both groups, reaching thelowest level at 2 months of age. This observationcorroborates with those found by KUMAR et al.(2008), where they reported that total specific IgGlevels did not differ statistically from control valuesin foals at the age of two months. Further, a studyperformed by our group (VIANNA et al., 2019),suggests the administration of a third dose around60 days after the first vaccination in horses usingrEMA-2. Specific IgG ELISA results demonstratedthat foals born from mares vaccinated against S. equihad an increase of 34.3 times de initial optical densityafter colostrum absorption, whereas foals born fromcontrol mares had an increase of only 5.9 times theinitial optical density. Although optical density doesnot directly correlate with IgG levels, these resultssuggest an increase in antibody levels in foals bornfrom vaccinated mares. What is interesting is thateven with a statistical difference in optical densitybetween these groups over the first two months, itremained at the same levels, differing from resultsfound in foals born from mares vaccinated againstT. equi. In 2018, RIBAS et al. reported that maternalantibodies against S. equi remain circulating infoals until 3 months of life, which suggests thatimmunization schedule should start at this age, whenmaternal antibodies decay. This data corroborateswith the results found in the present study. A similarcolostrum immunoglobulin duration was observedby CAUCHARD et al. (2004), evaluating a vaccineagainst Rhodococcus equi. Studies of IgG subisotypesin the transfer of passive immunity remain scarce,especially in mares vaccinated against T. equi andS. equi. The predominance of IgG3/5 in the vaccineresponse may suggest that the vaccine used inducesprotection (WILSON et al., 2001). In animals naturallyinfected by T. equi, IgG3/5 predominates, suggestingthat this is the main subisotype involved in parasitecontrol (MEALEY et al., 2012). In convalescentanimals which were previously infected by S. equi,IgG4/7 and IgG3/5 were the main subisotypesidentified (SHEORAN et al., 1997), similar to theresults observed in our study. The isotyping resultsresemble those reported by MEALEY et al. (2012)and SHEORAN et al. (1997) in naturally infectedanimals, suggesting that the vaccine antigens mimicthe natural immune response.As previously described by PERKINS& WAGNER (2015), equine colostrum is directlyrelated to maternal serum immunoglobulin, withIgG4/7 predominating, followed by IgG1 andIgG3/5. The immunoglobulin IgG4/7 plays anessential role in protection against bacterial andviral infections (LOPEZ et al., 2002). Both IgG1and IgG3/5 are substantially raised in colostrum andmediate immune functions in protecting the newbornPERKINS & WAGNER (2015). Mare vaccination atthe end of gestation is essential in order to concentrateneutralizing antibodies, which can protect the foalduring the first months of age (LOPEZ et al., 2002).The subisotype IgG3/5 predominated infoals born from T. equi vaccinated mares, followed byIgG4/7 and IgG1, with detectable levels up to 30 daysof life. In foals born from S. equi vaccinated mares,the subisotypes IgG3/5 and IgG4/7 were detected atsignificant levels up to 7 days of life. This observationis quite important considering that IgG3 is the mostimportant equine IgG subclass and can trigger a strongrespiratory burst via the Fc receptor. Additionally, thesubisotypes IgG1, IgG4-7 and IgG3-5 observed invaccinated mares can promote Fc-receptor interactionsand complement activation (LEWIS et al., 2008).In the present study, antibodies against T.equi and S. equi antigens were detected in the firstCiência Rural, v.52, n.8, 2022.
Passive immunity in foals born from mares vaccinated against Theileira equi and Streptococcus equi subspecies equi.serum samples of vaccinated and control mares(D0), which may suggest previous contact withthese pathogens. Some initial value was expected,possibly due to previous contact with the pathogens,given that T. equi is endemic in the study region andas such may persist in the herd by asymptomaticcarriers (WISE et al., 2014). The same could beattributed to S. equi, since strangles is also prevalentin the Rio Grande do Sul state, where the study wasperformed (MORAES et al., 2009). Given the age ofthe mares enrolled in this study and the prevalenceof strangles in this region, contact with the agent islikely to have occurred at least once over the courseof their lifetime, which may explain the serologicalfindings. However, one may consider a characteristicbackground of non-competitive serological reactions,especially identified in equine serum (CRAIGO etal., 2012). Nevertheless, in comparison to the groupsvaccinated against T. equi and S. equi, the totalspecific IgG levels of control animals remained linearduring the study period, indicating that there were nooutbreaks during the experimental period.Vaccination against T. equi and S. equi hasnot yet reached a consensus across equine breeders andveterinarians. The fact that there are no commercialvaccines available against T. equi suggests thata certain level of doubt concerning the benefitsof the vaccine could exist (ROTSCHILD, 2013).Although there are S. equi vaccines available, theirefficacy is often questioned (ARIAS GUTIÉRREZ,2013). Commercial and experimental vaccinesstill require further study, especially regardingantigenic variability and immunogenicity (ARIASGUTIÉRREZ, 2013), which may have contributed totheir not being widely adopted in vaccine protocols.In practice, the use of experimental vaccines increasesafter the occurrence of outbreaks. Although antibodyvalues do not necessarily indicate protection, clinicalobservations on properties that regularly vaccinate doindicate a decrease in the number of cases, suggestinga relationship with herd immunity.CONCLUSIONMares vaccinated at 300 days of gestationhad higher total specific vaccinal antibodies for bothvaccines, with a similar profile of total specific IgGand subisotypes transferred to their foals. Basedon the present study, one can suggest that the ageof two months could be the ideal time to start theT. equi immunization in foals, if a vaccine were tobe available. On the other hand, considering thepresent and previous studies, the age of 3-4 months7can be suggested as the ideal time to start S. equiimmunization in foals.ACKNOWLEDGEMENTSWe would thank to Coordenação de Aperfeiçoamentode Pessoal de Nível Superior (CAPES) - Brazil for ACS, RPS,and RP scholarships - Finance Code 001 and Conselho Nacionalde Desenvolvimento Científico e Tecnológico (CNPq) for VM,CEWN and FPLL scholarships.DECLARATIONINTERESTOFCONFLICTOFWe have no conflict of interest to declare.AUTHORS’ CONTRIBUTIONSACS contributed to experiment design, experimentsand writing the manuscript. CEWN contributed to experimentdesign, analyses of results and manuscript revision, LQNcontributed to experiment design, VM contributed to theexperiments and manuscript revision, RPS contributed to theexperiments and manuscript revision, RP contributed to theexperiment and manuscript revision, and FPLL contributed todesigned the study, analyses of results and manuscript revision.BIOETHICSANDCOMMITTEE APPROVALBIOSSECURITYAll procedures carried out in this study were approvedby the Ethical Committee for Animal Experimentation at theUniversidade Federal de Pelotas (CEEA-UFPel), under protocol 7896.REFERENCESARIAS GUTIÉRREZ M. P. Strangles: the most prevalentinfectious respiratory disease in horses worldwide. CES MedicinaVeterinaria y Zootecnia. v.8, n.1, p.143-159. Available from: view/2840 .Accessed: Mar. 02, 2021. doi: 10.21615/2840.BORDIN, A. I. et al. Imunogenicity of an electron beam inactivatedRhodococcus equi vaccine in neonatal foals. PLoS ONE. v.9,n.8, p.1-11. Available from: 14/pdf/pone.0105367.pdf . Accessed: Apr. 28,2021. doi: 10.1371/journal.pone.0105367.CAUCHARD, J. et al. Foal IgG and opsonizing anti-Rhodococcusequi antibodies after immunization of pregnant mares with aprotective VapA candidate vaccine. Veterinary Microbiology.v.104, n.1-2, p.73–81, 2004. Available from: https://pubmed.ncbi.nlm.nih.gov/15530741/ . Accessed: Mar. 04, 2021. doi: 10.1016/j.vetmic.2004.09.006.CRAIGO, J. K. et al. Development of a high throughput, semiautomated, infectious center cell-based ELISA for EquineInfectious Anemia Virus. Journal of Virological Methods. v.185,n.2, p.221–227, 2012. Available from: 74/ . Accessed: Mar. 03, 2021. doi:10.1016/j.jviromet.2012.07.007.Ciência Rural, v.52, n.8, 2022.
8Santos et al.CUNHA, C. W. Development of specific immunoglobulin Ga(IgGa) and IgGb antibodies correlates with control of parasitemiain Babesia equi infection. Clinical and Vaccine Immunology.v.13, p.297–300, 2006. Available from: https://cvi.asm.org/content/13/2/297 . Accessed: Mar. 04, 2021. doi: 10.1128/CVI.13.2.297-300.2006.FLOCK, M. et al. L. Recombinant Streptococcus equi proteinsprotect mice in challenge experiments and induce imune responsein horses. Infection and Immunity. v.72, n. 6, p.3228-3236,2004. Available from: https://iai.asm.org/content/72/6/3228 .Accessed: Mar. 03, 2021. doi: 10.1128/IAI.72.6.32
Transfer of passive immunity against both antigens was observed with specific IgG values in colostrum and foals' serum proportional to mares' values. The most detected specific IgG subisotypes were IgG3/5 and IgG4/7 for both antigens. Foals born from mares immunized with T. equi kept maternal IgG values until 2 months of age, while those .
The onset of immunity against MD has been shown from 4 days of age. NO IMMUNITY GAP The immunity gap between waning of passive immunity and the onset of active immunity. During this period, birds are unprotected against IBD virus infection. vvIBDv or variant Active immunity Passive immunity Age AB titre Protective level Classical IBD vaccination
Prevention and Control - passive and active immunization How do we acquire immunity? Passive Immunity in Infants Artificial Passive Immunity Gamma globulin - Ig's from pooled blood of at least 1,000 human donors variable content non-specific Specific immune globulin - higher titers of specific antibodies Artificial Passive Immunity
immunity) Inherited immunity to certain diseases, born with genetic information that provides immunity to certain diseases. Acquired Immunity: Received during a person's lifetime, achieved naturally or artificially. Naturally Acquired Immunity: Own body produced antibodies ( also called active immunity- generally long lasting).
This immunity (called maternal or passive immunity) protects the young bird from diseases, but prevents the bird's body from mounting an immune response and is short lived. At 3 days of age about half of the passive immunity is lost. Very little passive immunity is present at 2 weeks and at 3 weeks it is completely gone (Cutler, 2002).
Active Immunity Immunity develops over time as a result of the body's contact with antigens Causes B cells to secrete the antibodies for the antigen Memory Cellsprovide long lasting immunity Natural Active Immunity Occurs when you are naturally exposed to antigen Acquired Active Immunity Occurs when you are injected with .
Types of Immunity Humoral immunity antibody -mediated immunity Provided by antibodies present in body fluids Cellular immunity cell -mediated immunity Targets virus -infected cells, cancer cells, and cells of foreign grafts _ _ _
Natural and passive immunity: maternal antibodies and lactogenic immunity 101 2.1. Natural passive immunity 102 Passive immunisation is widely used in Nature to protect offspring against disease at 103 birth and during lactation (mammals) or in ovo (birds and fish). This is achieved by
Anatomy is largely taught in the early years of the curriculum, with 133 some curricula offering spiral learning into later years (Evans and Watt, 2005). This 134 spiral learning frequently includes anatomy relating to laparoscopic, endoscopic, and . 7 .
