Lamb model in the study of immunity to enteropathogenic Escherichia coli infections

Three groups of ewes were vaccinated with formalin inactivated, whole cell, aluminum hydroxide adjuvanted bacterins prepared from capsulated enteropathogenic Escherichia coli (EEC). Lambs born to and suckling these ewes, compared with lambs of nonvaccinated control ewes, were highly resistant to homologous EEC challenge exposure. Lambs of ewes vaccinated with products prepared from K99 antigen-positive, noncapsulated E coli were highly resistant to heterologous EEC challenge exposure. In both cases, lambs of vaccinated ewes had significantly (P less than 0.005) less morbidity and mortality, fewer challenge inoculum-type E coli per rectal swab evaluation, and had superior weight gains over a 4-day period. Immunoglobulin assay of 122 lamb sera (collected 12 hours after birth) failed to reveal any correlation between serum immunoglobulin values and morbidity or mortality. When tested by plate agglutination technique, using whole cell antigens, or by reverse radial immunodiffusion, using purified capsular antigens, colostral whey samples of vaccinated ewes did not have increased capsular antibody titers. The K99 serum antibody values of K99 antigen-vaccinated ewes were markedly higher than were those of ewes vaccinated with other bacterins or of control ewes.     

Brucella abortus-specific immunoglobulin isotypes in serum and vaginal mucus from heifers vaccinated with Brucella abortus salt-extractable proteins and challenge exposed with virulent Brucella organisms

Serum and vaginal Brucella-specific immunoglobulin isotypes (IgG1, IgG2, IgM, and IgA), obtained from 62 crossbred beef heifers vaccinated with Brucella abortus salt-extractable proteins and subsequently challenge exposed with B abortus S2308, were studied. Brucella-specific IgG antibodies and Brucella-specific immunoglobulin isotypes were quantitated by a fluorometric immunoassay. Serum and vaginal immunoglobulin responses were evaluated as a method of distinguishing infected from noninfected heifers. Rivanol precipitation, complement-fixation, buffered-antigen brucellosis tests and an ELISA were performed on sera. For immunoglobulin isotypes, vaccinated heifers had mean antibody responses higher than baseline mean antibody responses for at least 31 weeks after vaccination. After challenge exposure, significant differences (P greater than 0.05) were not detected between mean antibody responses of vaccinated and nonvaccinated heifers. Vaginal Brucella-specific antibody responses did not correlate with protection from disease. Vaginal Brucella-specific IgM was detected only at the time of abortion. Vaginal IgA appeared specific for identification of virulent B abortus infection. All serotests appeared adequate in distinguishing baseline titers from titers of heifers that had aborted and were considered bacteriologic culture-positive. Results of serotests neither consistently distinguished vaccinates from challenge-exposed cattle nor distinguished heifers that were challenge exposed, had aborted, and were considered bacteriologic culture-positive adequately from heifers that were challenge-exposed, had not aborted, and were considered bacteriologic culture-negative. Brucella-specific IgA appeared to be the most effective in distinguishing vaccinated heifers from challenge- exposed heifers and heifers that were challenge exposed and had aborted, from heifers that were challenge exposed and had not aborted. Brucella-specific serum IgA was detected up to 13 weeks after abortion.     

Effects of an orally administered live Escherichia coli pilus vaccine on duration of lacteal immunity to enterotoxigenic Escherichia coli in swine

Primigravid swine were vaccinated orally with a live enterotoxigenic Escherichia coli (ETEC) strain that produces pilus antigen K99. The titers of K99 antibody in colostrum and milk of vaccinates remained higher than those of nonvaccinated controls through the first lactation after vaccination (4 weeks). Some control swine had low titers of K99 antibody in colostrum or developed low titers of K99 antibody in milk during lactation. Lacteal K99 antibody titers of vaccinates dropped to control levels during the second lactation, 6 months after vaccination. Pigs suckling vaccinates and controls were equally susceptible to challenge exposure to K99+ ETEC during the second lactation. Orally vaccinated swine given a parenteral booster vaccination (with killed K99+ ETEC) during their second gestation had K99 antibody in milk through their second lactation. During the second lactation, these orally vaccinated parenterally revaccinated swine had higher titers of K99 antibody in postcolostral milk than did nonvaccinated controls, controls given only the parenteral booster injection, or controls vaccinated parenterally during both gestations.     

Immune response to Neospora caninum in naturally infected heifers and heifers vaccinated with inactivated antigen during the second trimester of gestation

The objective of this study was to compare the immune response to Neospora caninum in naturally infected heifers and heifers inoculated with a killed whole N. caninum tachyzoite preparation during the second trimester of gestation. Nine Holstein heifers were used in this study; three naturally infected heifers were born from seropositive dams, and six seronegative heifers were born from seronegative dams. Four seronegative heifers were subcutaneously vaccinated with a killed whole N. caninum tachyzoite preparation at weeks 13, 15 and 17 of gestation. A killed whole N. caninum tachyzoite preparation containing 45 mg of protein/5 ml dose was formulated with 70% of mineral oil adjuvant (13% consisting of Arlacel C, 85% Marcol 52 and 2% Tween-80). Similarly, two seronegative heifers (negative controls) were inoculated with mock-infected bovine monocytes in oil adjuvant. Humoral immune responses were tested by using an indirect fluorescent antibody test (IFAT) and an indirect enzyme-linked immunosorbent assay (ELISA) for detecting isotype specific antibodies. Cellular immune responses were assessed by lymphocyte proliferation test (LPT) and IFN-gamma production. N. caninum-specific antibody responses increased in immunized cattle by week 15 of gestation (mean reciprocal antibody titers 450+/-252), peaked at week 23 (mean 16,000+/-6400). Maximum antibody response in naturally infected heifers was observed at week 19 of gestation (mean: 3467+/-2810). Mean serum IFAT titers were significantly higher in immunized heifers compared with those in naturally infected heifers from weeks 17 to 25 (P < 0.05). Analysis of isotype specific antibodies in naturally infected heifers revealed a predominant IgG1 response in one heifer and a predominant IgG2 response in the other two. Similar titers of IgG1 and IgG2 occurred in immunized heifers. Control heifers remained seronegative throughout the study by IFAT and ELISA. Significant antigen-specific proliferation responses were only detected in naturally infected heifers in week 19 of gestation. Peripheral mononuclear blood cells (PMBC) from immunized animals produced IFN-gamma in similar concentrations to those of infected animals (P > 0.05). No abortion was seen in any experimental group; however, one calf from a vaccinated heifer died due to dystocia. All calves from vaccinated and control heifers were seronegative by IFAT at 6 months of age; in contrast, calves born from naturally infected heifers remained seropositive with titers > or = 200. Killed vaccine induced similar immune responses to those found in chronically, naturally infected cattle which did not abort; however, different immune pathways may be followed in vaccinated and natural infected heifers with differences in degree of protective immunity.     

Relationship among transmissible gastroenteritis virus antibody titers in serum, colostrum, and milk from vaccinated sows, and protection in their suckling pigs

We studied the antibody responses to transmissible gastroenteritis (TGE) in serum, colostrum, and milk from sows vaccinated with 2 attenuated (1 IM and 1 oral-IM) and 1 nonattenuated live vaccines and the relationship of these responses with the survivability of the sow's suckling pigs after challenge exposure with virulent TGE virus. Contrary to previous studies, the anti-TGE virus-neutralizing geometric mean titers (GMT) in the milk of sows vaccinated with attenuated vaccines at 3 and 5 days of lactation were similar to that found in the colostrum. Colostral and serum antibody titers were highest in sows given 2 injections of the IM attenuated vaccine. Half of the sows given the oral-IM attenuated vaccine did not seroconvert after 2 oral doses. Only sows vaccinated with the nonattenuated live vaccine had milk GMT that remained high for 21 days after farrowing. The linear relationship between colostral GMT and percentage of survivability of suckling pigs challenge exposed at 3 days of age was significant (P less than 0.05), although the relationship between serum GMT and percentage of survivability and the relationship between milk GMT and percentage of survivability were not significant (P greater than 0.10). The linear relationship between colostral (P less than 0.10) or pre-challenge exposure milk (P less than 0.05) GMT and percentage of survivability of suckling pigs challenge exposed at 5 days of age was significant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Active and Passive Immunity to Bovine Viral Respiratory Diseases in Beef Calves After Shipment

Fifteen steers were vaccinated after shipment with a modified live virus vaccine containing infectious bovine rhinotracheitis (IBR), bovine virus diarrhea (BVD), and bovine myxovirus parainfluenza-3 (PI3), and 16 unvaccinated steers were kept as controls. Geometric mean titers one month after vaccination were highest to BVD, followed by PI3 and IBR. Weight gains were higher during 30 days after vaccination in the controls. One case of acute respiratory disease developed in one vaccinated calf. Revaccination 79 days after the first dose increased antibody to PI3 and BVD virus but not IBR. In a second trial, no clinical respiratory disease developed after shipment of 13 heifers that received an antibacterial-antiviral antiserum or in the 12 controls. Weight gains 30 days after shipment were identical in both groups.     

Bordetella rhinitis in pigs: serum and nasal antibody response to Bordetella bacterins.

The nasal and serum antibody response of two groups of pigs, vaccinated with adjuvant containing formalinized or sonicated Bordetella bronchiseptica bacterins was compared with the response of a nonvaccinated group. The tube agglutination test was used to determine agglutinin titers. Following vaccination, all pigs were challenged intranasally with the vaccine strain of Bordetella, after which the nasal Bordetella flora of vaccinated and nonvaccinated pigs was investigated. Sera and nasal secretions from both vaccinated groups exhibited markedly higher agglutinin titers than the control group and serum titers were higher than those in nasal secretions. No differences in agglutinating antibody response were evident between the two vaccines. Serum antibody titers exceeded nasal titers and persisted over a longer period of time. Systemic vaccination resulted in an increased nasal clearance of the vaccine strain by the groups of pigs vaccinated with sonicated or formalined bacterin, whereas no such clearance was evident in the nonvaccinated control group.     

Efficacy of colostral immunoglobulins for therapeutic and preventive treatments of calf diarrhea.

Pooled colostral milk samples were collected from apparently healthy Holstein cows. Immunoglobulin (Ig) was partially purified from the colostral milk and concentrated by freeze drying. The Ig powders had neutralizing antibody titers of 1:6,250 to 1:31,250 against bovine rotavirus (RV), and reacted with four RV proteins of VP2, VP4, VP6, and VP7. No therapeutic effect of Ig powder showed on clinically serious diarrhea with RV in dairy and beef calves. However, the Ig powder had a preventive effect on the diarrhea in beef calves when it was given soon after calving.     

A double-protease-resistant variant of transmissible gastroenteritis virus and its ability to induce lactogenic immunity

A virus resistant to 2 major intestinal proteases (trypsin and alpha-chymotrypsin) was derived from the attenuated Purdue strain of transmissible gastroenteritis virus. Its enzymatic stability was confirmed, in vitro, by exposure to proteolytic enzymes and to porcine intestinal fluids. Vaccination of 5 seronegative pregnant sows with the variant virus by a series of 2 oral and 1 IM inoculations resulted in high titers of neutralizing antibody in serum and colostrum. The mean antibody titer in milk whey decreased 44-fold within 1 week after parturition. At 3 days of age, the 40 pigs delivered by these sows were challenge exposed orally with virulent transmissible gastroenteritis virus. Pigs nursing the 5 vaccinated sows underwent a relatively mild clinical course of illness. The average mortality of these 40 pigs was 33%. Thirty-six pigs which had been raised by 4 nonvaccinated sows had a more severe illness, greater daily weight loss, and higher mortality (92%).     

Effect of oral inoculation of Escherichia coli on colostral antibody production in cattle.

Oral inoculation of approximately 1.2 x 10(9) viable Escherichia coli to pregnant cows resulted in increased blood serum and colostral whey titers to the "O" antigen. The antibody titers were more pronounced in colostral whey and were correlated with the inoculum strain of Escherichia coli. There was no correlation between antibody titers of the colostrum ingested and the resulting serum antibody titers of the calves. The incidence of diarrhea in calves did not correlate with the antibody titer in the colostrum. The occurrence of diarrhea was significantly greater in calves that did not ingest colostrum until they were 12 hours old, compared with calves that had free access to their dams and suckled within an hour of birth.     

Immunity to Escherichia coli in pigs: Antibody Secretion by the Mammary Gland after Intramammary or Intramuscular Vaccination with an E. coli Vaccine

Indirect hemagglutinating antibody titres in individual gland samples of colostrum and milk from 13 sows were measured. Five of the sows were vaccinated via a mammary gland and five by the intramuscular route with a live formalinised Escherichia coli vaccine and three remained as non-vaccinated controls.

Antibody titres were higher in colostral and milk whey from the vaccinated sows than from non-vaccinated groups. The inoculated gland in the group of sows given vaccine by the intramammary route secreted milk containing markedly more antibodies to the vaccine E. coli strain than did the non-vaccinated glands. Milk from the vaccinated gland did not contain higher titres to heterologous E. coli O antigens than milk from non-vaccinated glands. Serum titres were the same or higher than the titres in colostrum from non-vaccinated glands.

     

Fetal protection against continual exposure to bovine viral diarrhea virus following administration of a vaccine containing an inactivated bovine viral diarrhea virus fraction to cattle

OBJECTIVE: To evaluate the efficacy of a commercially available killed bovine viral diarrhea virus (BVDV) vaccine to protect against fetal infection in pregnant cattle continually exposed to cattle persistently infected with the BVDV. ANIMALS: 60 crossbred beef heifers and 4 cows persistently infected with BVDV. PROCEDURES: Beef heifers were allocated to 2 groups. One group was vaccinated twice (21-day interval between the initial and booster vaccinations) with a commercially available vaccine against BVDV, and the other group served as nonvaccinated control cattle. Estrus was induced, and the heifers were bred. Pregnancy was confirmed by transrectal palpation. Four cows persistently infected with BVDV were housed with 30 pregnant heifers (15 each from the vaccinated and nonvaccinated groups) from day 52 to 150 of gestation. Fetuses were then harvested by cesarean section and tested for evidence of BVDV infection. RESULTS: 1 control heifer aborted after introduction of the persistently infected cows. Bovine viral diarrhea virus was isolated from 14 of 14 fetuses obtained via cesarean section from control heifers but from only 4 of 15 fetuses obtained via cesarean section from vaccinated heifers; these proportions differed significantly. CONCLUSIONS AND CLINICAL RELEVANCE: A commercially available multivalent vaccine containing an inactivated BVDV fraction significantly reduced the risk of fetal infection with BVDV in heifers continually exposed to cattle persistently infected with BVDV. However, not all vaccinated cattle were protected, which emphasizes the need for biosecurity measures and elimination of cattle persistently infected with BVDV in addition to vaccination within a herd.     

Clinical evaluation of the efficacy of inoculating cattle with a vaccine containing Tritrichomonas foetus.

To test the efficacy of a polyvalent Tritrichomonas foetus vaccine, 130 nulliparous heifers were randomly assigned to either receive the test T foetus vaccine or to serve as nonvaccinated controls. The polyvalent test vaccine consisted of a Campylobacter fetus/Leptospira canicola-grippotyphosa-hardjo-icterohaemorrhagiae-pamona bacterine containing 5 x 10(7) killed T foetus/dose. The polyvalent control vaccine consisted of the aforementioned formulation without T foetus. Heifers were administered 2 doses of control or experimental vaccine at 3-week intervals. Heifers were bred to T foetus-infected bulls and their conception and pregnancy rates were determined throughout gestation. In addition, serum samples were analyzed to determine induced concentrations of antitrichomonal antibodies and vaginal secretions were sampled to determine T foetus infection rates in control and vaccinated animals. One week after each of the 15-day breeding periods, 60% (6 of 10) of tested vaccinates and 80% (8 of 10) of tested control animals were T foetus culture-positive. The mean duration of infection of vaccinates was 3.8 weeks (+/- 7.5 days), compared with 5.4 weeks (+/- 7.5 days) of infection for control heifers. All vaccinates developed increased immunofluorescence and serum neutralizing antibody titers following the first immunization, and had additional increases of at least fourfold in response to the second injection. In contrast, no consistent increase in immunofluorescence or serum neutralizing antibodies was observed in control animals. Conception rates were 89.2% for vaccinates and 85.9% for control animals 30 days after breeding and 80 to 90% of these remained pregnant 60 days after breeding.(ABSTRACT TRUNCATED AT 250 WORDS)     

Q fever (Coxiella burnetii) investigations in dairy cattle: persistence of antibodies after vaccination.

The immune response and persistence of antibodies were investigated in dairy cattle vaccinated with formalin-inactivated phase (ph) I Coxiella burnetii vaccine agglutinating antibody geometric mean titer (GMT) of 193.2 at 1 month after vaccination compared to a GMT of 2.0 for nonvaccinated calves. The agglutinating antibodies gradually decreased in vaccinated cattle, but the GMT remained approximately 4 times higher than that for the nonvaccinated group for at least 20 months. Results of serotests at 2 months after revaccination indicated a rapid increase in the GMT to 177.0 with agglutinating titers between 1:64 and 1:512.     

Brucella abortus-specific immunoglobulin in isotypes in serum and vaginal mucus from cattle vaccinated with strain 19 and challenge exposed with virulent strain 2308

The immunoglobulins (IgG1, IgG2, IgM, and IgA) of the Brucella-specific antibody response of 69 crossbred beef heifers were studied after Brucella abortus strain 19 vaccination and strain 2308 challenge exposure. The immunoglobulin isotype responses in serum and vaginal mucus were measured by use of fluorescent immunoassay. Serum antibody responses were detected also by 3 standard serologic tests (complement fixation [CF], Rivanol precipitation, and the CARD test] and 2 primary bindings assays that detect IgG antibodies. One month after vaccination, mean antibody titers for all immunoglobulin isotypes were higher for vaccinated cattle (n = 46) than for nonvaccinated controls (n = 23). After vaccination, IgA antibody responses in vaccinated cattle were only 2-fold higher than those for controls, whereas IgG1, IgG2, and IgM antibody responses were 3- to 90-fold greater than those for controls. Measurement of IgA antibody responses classified 21 of 39 vaccinates as seropositive after vaccination, whereas the other isotypes classified 28 or 34 cattle as seropositive. Three months after challenge exposure, the mean antibody responses for each isotype were higher in cattle that aborted or were culture positive than in cattle that did not abort and were culture negative. Although IgG1, IgG2, and IgM antibody titers were each of benefit in identifying B abortus-infected cattle, it did not appear that the magnitude of the antibody responses provided sufficient discrimination between S19-vaccinated cattle and S2308 challenge-exposed cattle. Serum IgA antibody responses were 10-fold higher after challenge exposure than after vaccination and may be a response to mucosal infection with the virulent organism.(ABSTRACT TRUNCATED AT 250 WORDS)     

Clostridial antibody response from injection-site lesions in beef cattle, long-term response to single or multiple doses, and response in newborn beef calves.

Experiments were conducted to compare clostridial antibody response of beef heifers that do and do not develop injection-site lesions, evaluate long-term antibody response of a single- and multiple-dose toxoid, and evaluate the ability of a clostridial toxoid to elicit an active antibody response in newborn calves. In Exp. 1, 37 weaned heifers were vaccinated (d 0) with a clostridial vaccine (Alpha-7, 2 mL, s.c.). Serum samples were collected on d 0, 28, 56, 84, and 112 to determine clostridial antibody titers. On d 28, heifers were visually inspected and palpated for injection-site lesions. The percentage of heifers that developed lesions was 64.9%. Lesioned heifers had elevated antibody titers for Clostridium chauvoei (CC) on d 28 (P < 0.08) and 84 (P < 0.07) compared with non-lesioned heifers. Clostridium sordellii (CS) and perfringens type D (CPD) antibody titers were greater in lesioned heifers than in non-lesioned heifers on d 28 and 56. In Exp. 2, long-term antibody response of Alpha-7 (A7) and Ultrabac 7 (UB7) was investigated in stocker heifers. The A7 heifers (n = 15) received one 2-mL vaccination (d 0), and the UB7 heifers (n = 15) received a 5-mL vaccination on d 0 and 28. Blood samples were collected on d 0, 28, 56, 84, 112, 140, and 180. Clostridium chauvoei, CPD, and Cl. novyi (CN) antibody titers from the A7 heifers were greater than those from the UB7 heifers on d 28. Due to the second UB7 injection, CC, CS, CN, and Cl. perfringens type C (CPC) antibody titers were greater in UB7 heifers than in A7 heifers on d 56. By d 112, titers were not different, and by d 140 all antibody titers were below detectable levels. In Exp. 3, 58 pregnant, mature, crossbred cows were vaccinated with A7 before calving. At birth, calves were carefully observed to ensure consumption of colostrum. Calves were blocked according to parturition date, and calves in each block were randomly allocated to receive A7 (s.c. at 3 +/- 3 d of age) or remain unvaccinated controls. Calves were bled at the time of vaccination (d 0) and on d 28, 56, 84, and 112. Antibody titers for CC, CPC, and CPD were elevated on d 0 and decreased throughout the experimental period (P < 0.01), but no titer differences (P > 0.10) were detected between treatment groups on any of the days sampled. These data indicated that antibody titers against clostridial diseases are enhanced when injection-site lesions develop. One injection of Alpha-7 seemed to provide the same length of protection as two injections of Ultrabac 7.     

Bovine antibody against Streptococcus agalactiae, type Ia, produced by preparturient intramammary and systemic vaccination.

Four pregnant heifers were immunized by the intramammary route with killed or live Streptococcus agalactiae vaccine, and a 5th heifer was vaccinated by the intramuscular route with killed vaccine. Antibody in the colostrum from vaccinated and non-vaccinated glands was compared. Antibacterial glands was compared. Antibacterial antibody titers of the 4 immunoglobulin classes were determined by indirect fluorescent antibody assay. Although the content of immunoglobulin G1 (IgG1), IgG2, and IgM in the colostrum from the vaccinated glands was not substantially different from the nonvaccinated glands, IgA content was considerably greater in the former. Antibody specific to S agalactiae was isolated from all colostrum samples. The mouse passive protection test and Ouchterlony analysis were used to demonstrate the presence of type-specific antibody to Ia strain used for vaccination. The passive mouse protection test also was useful to compare the protective capacity of specific S agalactiae, type Ia, antibodies of immunoglobulin classes IgG, IgM, and IgA. Increased protective capacity of IgM and IgA over IgG1, on a weight basis, was demonstrated. The present study indicates that S agalactiae preparations, when introduced into the mammary gland, can give rise to local antibody synthesis in the vaccinated glands.     

Immune response of pigs inoculated with virulent pseudorabies virus and pigs inoculated with attenuated or inactivated pseudorabies virus vaccine before and after challenge exposure

Pseudorabies virus (PRV) antibodies, detectable by indirect radioimmunoassay (IRIA), serum-virus neutralization test (NT), or microimmunodiffusion test (MIDT) were developed within 8 days after pigs were inoculated with virulent PRV or attenuated PRV vaccine. Indirect radioimmunoassay and NT titers in pigs inoculated with virulent PRV were developed at the same rate, with IRIA titers being higher than NT titers. Pigs inoculated with attenuated or inactivated PRV vaccine developed peak mean prechallenge NT antibody titers of 4 and 1 (reciprocals of serum dilutions), respectively. Pigs inoculated with attenuated PRV vaccine had peak mean prechallenge IRIA antibody titers of 6, whereas pigs inoculated with inactivated PRV vaccine had mean IRIA antibody titers of 64. Challenge exposure of swine inoculated with attenuated or inactivated PRV vaccine elicited quantitatively equivalent responses, as measured by IRIA or NT, which were higher than prechallenge titers. There were no false-positive IRIA, NT, or MIDT results obtained when sera from nonvaccinated, nonchallenge-exposed pigs were tested. It appears that the PRV infection status of a seropositive swine herd could be ascertained by serologically monitoring several representative animals from a herd, using the NT. If 2 or more tests of representative animals at 14-day intervals were done and the mean NT titer was 4 or less, it could be concluded that the herd was vaccinated against, but not infected with, virulent virus.     

Effects and use of a modified live Anaplasma marginale vaccine in beef heifers in California

Eighty-one 11-month-old, nonpregnant, Anaplasma marginale-seronegative beef heifers were allotted to 2 groups for evaluation of a modified live A marginale vaccine (n = 50 for vaccinated group and n = 31 for nonvaccinated group). The vaccine induced a mild form of anaplasmosis, as evidenced by a significant (P less than 0.01) decrease in the packed cell volume (PCV) between days 31 and 46 after vaccination. The lowest PCV was 11%, and 3 heifers had a PCV less than 20%. Slight lethargy was evident in some of the vaccinated heifers between days 30 and 45 after vaccination. All vaccinated heifers became seropositive to A marginale, as measured by the complement fixation test and the card test on days 35 and 42 after vaccination, respectively. All nonvaccinated heifers remained seronegative.     

Effect of vaccination of the dam on rotavirus infection in young calves

Vaccination of cows with a combined, inactivated, adjuvanted rotavirus and Escherichia coli vaccine resulted in increased neutralising antibody titres to rotavirus in serum and colostral whey. Evidence was obtained that vaccination resulted in a decreased incidence of rotavirus shedding and of abnormal faeces or diarrhoea in young calves fed colostrum and milk from the vaccinated dams. The E coli component of the vaccine was not evaluated because no natural challenge was evident.