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.     

Protection of the nursing pig against experimentally induced enteric colibacillosis by vaccination of dam with fimbrial antigens of E coli (K88, K99 and 987P)

Pregnant gilts were vaccinated with two doses of alhydrogel adsorbed fimbrial antigens of Escherichia coli (K88ab, K88ac, K99 and 987P) supplemented with beta toxoid of Clostridium perfringens type C. Their piglets, and piglets of nonvaccinated gilts, were subsequently orogastrically challenged with one or other of the four fimbrial types of enteropathogenic E coli. Some of the vaccinated animals were reinjected with a single dose of the vaccine during second gestation and their piglets, and piglets of non-vaccinated sows, were challenged the same way as were litters of gilts. Blood serum and colostra were examined for antibodies to the four fimbrial antigens of E coli and for antitoxin to beta toxin of C perfringens type C. It was found that: (1) a highly significant reduction in mortality and morbidity was achieved in vaccinated litters against all four challenge strains of E coli; (2) excretion of K88ab and K88ac but not of K99 and 987P challenge strains was significantly reduced; (3) revaccination of sows by a single dose of the vaccine during second gestation conferred complete protection against mortality and highly significant protection against morbidity; (4) no correlation was noted between colostral or seroagglutinins to fimbrial antigens of E coli and mortality rates in litters challenged with homologous fimbrial types of E coli, but good correlation was found between colostral precipitins to K88 antigens and mortality rates in litters; (5) antitoxin value in 97 per cent of colostrum of vaccinated sows was 10 iu equivalent of C perfringens type C toxin or more per ml of colostrum.     

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)     

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.     

Lesions of transmissible gastroenteritis virus infection in experimentally inoculated pigs suckling immunized sows

Intestinal lesions of transmissible gastroenteritis (TGE) virus infection in conventionally reared pigs suckling either nonvaccinated, vaccinated, or previously infected sows were studied by scanning electron microscopy, light microscopy, and immunofluorescent microscopy for TGE viral antigen. Pigs were inoculated with virulent TGE virus when they were 5 or 21 days old and were euthanatized shortly after the onset of diarrhea or 96 hours after inoculation if no diarrhea developed. Pigs inoculated when they were either 5 or 21 days old and suckling nonvaccinated sows developed severe lesions, including swelling and necrosis of enterocytes and severe villus atrophy. Pigs inoculated when they were 5 days old and suckling sows vaccinated with attenuated vaccines developed less-severe villus atrophy, and those suckling sows immunized by exposure to nonattenuated TGE virus developed moderate or no villus atrophy. Pigs inoculated when they were 21 days old and suckling sows vaccinated with attenuated vaccines had severe villus atrophy, whereas those suckling sows immunized by exposure to nonattenuated virus had more-moderate villus lesions. Villus atrophy was inhibited to various degrees in pigs suckling immunized sows, depending in part on the antibody titer in the colostrum and milk.     

Assessment of protective efficacy of live and killed vaccines based on a non-encapsulated mutant of Streptococcus suis serotype 2.

The protective efficacy of a live and killed non-encapsulated isogenic mutant of Streptococcus suis serotype 2 was determined in pigs, and compared with the efficacy of the capsulated wild-type strain. SPF pigs were vaccinated twice intramuscularly at 4 and 7 weeks of age with a dose of 1 x 10(9) formalin-killed CFU of the wild-type (WT-BAC), formalin-killed non-encapsulated mutant (CM-BAC) or live non-encapsulated mutant (CM-LIVE) strain. After 2 weeks, vaccinated pigs and non-vaccinated controls were challenged intravenously with 1 x 10(7) CFU of the homologous, wild-type S. suis serotype 2 strain. Protection was evaluated by clinical, bacteriological, serological and post-mortem examinations. All pigs vaccinated with WT-BAC were completely protected against challenge with the homologous serotype. Pigs vaccinated with CM-BAC were partially protected. Although all pigs vaccinated with CM-BAC survived the challenge, four out of five pigs developed clinical signs of disease for several days. Compared to the WT-BAC and CM-BAC, the CM-LIVE vaccine was less protective. Two out of five pigs vaccinated with CM-LIVE died in the course of the experiment and all of them developed specific clinical signs of disease for several days. The protective efficacy of the vaccines could be associated with serum antibody titers. Antibody titers against cells of wild-type and non-encapsulated mutant strains as well as against muramidase-released proteins (MRP) were high in pigs vaccinated with WT-BAC and CM-BAC. Pigs vaccinated with CM-LIVE showed lower antibody titers. Antibody titers against purified capsular polysaccharides (CPS) of S. suis serotype 2 were only found in pigs vaccinated with WT-BAC. These findings indicate that CPS and other bacterial components of WT-BAC are probably essential for full protection against homologous challenge.     

Prevalence of four enterotoxin (STaP, STaH, STb, and LT) and four adhesin subunit (K99, K88, 987P, and F41) genes among Escherichia coli isolates from cattle

Colony hybridizations with DNA probes for 3 heat-stable (STaP, STaH, and STb) enterotoxins and 1 heat-labile (LT) enterotoxin and for 4 adhesins (K99, F41, K88, 987P) were performed on 870 Escherichia coli isolates to determine pathotypes prevalent among enterotoxigenic E coli (ETEC) isolated from cattle in Belgium. One hundred thirty-two E coli isolates (15.2%) hybridized with probes STaP, K99, and/or F41. The 5 other probes were not hybridized by E coli isolates. Therefore, only STaP enterotoxin and K99 and F41 adhesins were virulence factors of ETEC isolated from cattle. Two major pathotypes accounted for 95% of the ETEC: STaP+K99+F41+ (67.4%) and STaP+K99+ (27.3%). The last 5% of probe-positive isolates had STaP+, STaP+F41+, or K99+F41+ minor pathotypes. Of 12 American ETEC isolates also assayed, 7 were positive with STb and/or 987P probes (pathotypes STaP+STb+, STaP+ 987P+, or STaP+STb+987P+) and may be porcine- rather than bovine-specific enteropathogens. The remaining 5 American ETEC isolates belonged to 3 minor pathotypes (STaP+, STaP+F41+, and K99+F41+) also found among Belgian E coli isolates. Such isolates may be derivatives of STaP+K99+F41+ or STaP+K99+ ETEC after in vivo or in vitro loss of virulence genes and/or non-ETEC isolates, which have acquired virulence genes by in vivo transfer.     

Serological titers to various leptospiral serovars before and after vaccinating gilts with three commercial vaccines

The antibody response to various leptospiral serovars was evaluated in six-month-old gilts vaccinated with three commercial vaccines, each containing five leptospiral serovars.

All three vaccines elicited a significant postvaccinal antibody response to Leptospira canicola, grippotyphosa and icterohaemorrhagiae (copenhageni). The antibody response to the other leptospiral antigens in the vaccines varied among the vaccinates. None of the vaccinated groups developed significant titers to L. hardjo. Two of the three vaccines elicited a significant postvaccinal response to L. pomona, but in each case the titer mean of the vaccinated group was <1/100. Although not among the antigens in the vaccines, titers to L. bratislava increased in all vaccinated groups, except one, and in one control group.

     

Cross-protection studies between feline infectious peritonitis and porcine transmissible gastroenteritis viruses

Cross-protection studies between the feline infectious peritonitis (FIP) and the porcine transmissible gastroenteritis (TGE) viruses were conducted in cats, pigs and pregnant gilts. Cats vaccinated with TGE virus developed neutralizing antibodies against TGE virus and low titer antibody against FIP virus detected by an indirect fluorescent antibody technique but were not protected against a virulent FIP virus challenge. Baby pigs and pregnant gilts vaccinated with FIP virus did not develop detectable antibodies to TGE virus. Nevertheless, it appeared that vaccination of swine with FIP virus conferred some immunity against TGE virus infection. Seventeen-day-old pigs vaccinated with two doses of FIP virus had a 67% survival rate following a virulent TGE virus challenge, and 75% of the 3-day-old pigs suckling either FIP or TGE-virus-vaccinated gilts survived virulent TGE virus infection in contrast to 0% survival of baby pigs suckling unvaccinated gilts.     

猪口服免疫F18ac~+非产肠毒素大肠杆菌疫苗候选株后小肠免疫细胞的组织形态学特征

由F4+和(或)F18+产肠毒素大肠杆菌(ETEC)引起的腹泻和肠毒血症是乳猪及断奶仔猪的多发病。本文通过对断奶仔猪小肠淋巴样细胞亚群表型进行定量分析,检测和评估了F18ac+非ETEC弱毒疫苗候选株对F4ac+ETEC感染的免疫原性及保护效力;同时还评估了左旋咪唑作为一种免疫应答调节剂(IRM)的调节效能及其与试验疫苗联用的佐剂活性。     

The porcine humoral response to detergent extracted Aujeszky's disease (pseudorabies) virus antigens

Twenty Aujeszky's disease (AD) virus antigens were demonstrated by crossed immunoelectrophoresis in a Triton-X-100 detergent extract of virus-infected PK-1a cells. Eight of these antigens were shown to be glycosylated based on their ability to be specifically bound by the lectin Ricinus communis agglutinin II. Pigs nasally infected with AD virus showed a significant serum antibody titer to seven of the known glycosylated antigens and to four additional antigens. The antibody titer to these antigens persisted for at least 116 days. Pigs which were vaccinated parenterally with the whole detergent extract survived a nasal challenge of 10(8 . 5) PFU of virulent AD virus. The antibody response of these vaccinated pigs on the day of challenge was essentially identical to the recovery response previously observed in non-vaccinated nasally infected pigs. These results indicate that the optimum components of future AD virus subunit vaccines and their complementary diagnostic reagents should be selected from these 11 antigens.     

Efficacy of an inactivated virus vaccine for prevention of porcine parvovirus-induced reproductive failure.

Gilts vaccinated IM either once (4 gilts) or twice (2 gilts) with an acetylethyleneimine-inactivated porcine parvovirus (PPV) vaccine before they were bred were subsequently exposed intranasally and orally to virulent PPV at about the 40th day of gestation (from 37 to 43 days). At 2 weeks after vaccination, all had hemagglutination-inhibiting (HI) titers for PPV (from 20 to 80) which decreased by the time the immunity was challenged with virulent virus (from 10 to 40), but increased thereafter (from 160 to 1,280). Titers of singly and doubly vaccinated gilts were similar throughout the experiment. The gilts were killed at about the 84th day of gestation (from 80 to 87 days), and their litters were examined. Litters were comprised of 68 live fetuses and 1 dead fetus (7 to 14 fetuses/litter). Neither viral antigen, PPV, nor homologous HI antibody was found in any of the fetuses. In addition, 4 gilts were kept in contact with the vaccinated gilts and were treated similarly except for vaccination. These 4 gilts remained free of HI antibody until after they were exposed to virulent PPV during gestation. At the time the gilts were killed the titers were 1,280 to 2,560. Their litters were comprised of 11 live fetuses and 26 dead fetuses (8 to 11 fetuses/litter). Virus was isolated from fetuses of all litters. Viral antigen was found in 24 of the dead fetuses and 10 of the live fetuses. All infected live fetuses also had HI antibody for PPV. The 2 boars used to breed vaccinated and nonvaccinated gilts (usually each gilt was bred to each of the 2 boars), but not exposed to virulent PPV, remained free of HI antibody for PPV.     

Prevention of colibacillosis in neonatal swine with a 4-pilus E coli bacterin

Of 12 pregnant swine (vaccinates) given a 4-pilus enterotoxigenic E coli (ETEC) bacterin (K88, K99, 987P, F41), all developed comparable or significantly higher serum and colostral antibody levels than those of 8 pregnant swine (controls) given a 3-pilus ETEC bacterin (K88, K99, 987P). When piglets were challenged with an ETEC strain bearing the F41 antigen, those from vaccinates had significantly lower mortality, less scours, less severe clinical signs and better weight gain than those from controls.     

Comparative investigations of a combined vaccine against parvovirus and erysipelas and corresponding monovaccines in different vaccination schedules. 1: Field trial]

In a field trial, the development of antibodies of a combined vaccine against the porcine parvovirus (PPV) as well as against swine erysipelas was compared with corresponding mono vaccines. Furthermore, these vaccines were used in different vaccination schedules. The tests were carried out on 109 gilts in three closed farms. In all gilts, a basic immunization repeated twice was carried out at the age of six months and at intervals of three weeks. The revaccination was carried out four months after the basic immunization with half of the animals, and six months after the basic immunization with the remaining gilts. Between the combined vaccine and the mono vaccine no significant differences in the development of antibodies against PPV could be found according to different vaccination schedules. The gilts having been vaccinated with the mono vaccine and boostered six months later showed significantly higher antibody titers against Erysipelothrix rhusiopathiae. Between the remaining vaccination groups no significant difference in the development of the antibodies against swine erysipelas could be found. On only one farm, a continuous decrease of antibody titers against PPV in case of altogether 238 non-vaccinated piglets until the sixth month of life could be observed. On the two other farms, an increase of antibody titers against PPV could be found at different points of time, which indicates an infection of the piglets. Between the individual vaccination groups no significant antibody titers against PPV could be measured in milk tests. With regard to the number of piglets born alive per litter, the number of piglets born dead per litter and the number of mummies, a significant difference could neither be found between the vaccination groups 1-4.     

Vaccination Against Porcine Parvovirus Infection

Of 13 gilts 7 were vaccinated twice at an interval of 3 weeks with an inactivated vaccine against porcine parvovirus (PPV) infection, while the 6 nonvaccinated gilts served as controls. Starting after the 1st vaccination the gilts were bred and, after about 40 days of gestation, challenged intravenously with virulent PPV. The vaccinated gilts produced an antibody respons after the 1st and 2nd vaccination compatible with a primary and a secondary immune response, respectively. The nonvaccinated gilts remained low-titered or PPV antibody negative until after challenge. The gilts were killed after about 90 days of gestation, and their litters were examined. All of 53 fetuses from the vaccinated gilts were alive, and infection with PPV could not be demonstrated. Conversely, 50 of 65 fetuses from the non-vaccinated gilts were infected with PPV, and 43 were dead.In a field study comprising 2 herds, PPV seronegative or lowtitered gilts were vaccinated before mating. There were no obvious signs of reproductive disorders in the 2 herds during the vaccination trials, and the reproductive performance of vaccinated gilts did not differ significantly from that of non-vaccinated gilts.     

H9亚型禽流感病毒流行毒株交叉免疫攻毒保护试验

采用1998-2009年在河北、河南及山东分离的3株禽流感H9亚型流行毒株,分别制备灭活疫苗,免疫SPF鸡,免疫后21 d,采血测定HI抗体,然后用从上述3个地区及北京分离的共5株禽流感H9亚型流行毒株进行攻击,观察不同时期及地点分离的H9亚型流行毒株的交叉免疫攻毒保护效果。结果显示,用不同时期及地点的3个分离毒株所制备出的灭活疫苗免疫鸡后,各免疫组试验鸡H9亚型禽流感的HI抗体效价均明显上升,不同毒株灭活疫苗所诱导产生的HI抗体效价存在着不同程度的差异,用同源毒株作为抗原测定免疫组鸡的血清样品,可获得较高的HI抗体效价。攻毒试验结果证明,对不同时期及地点分离的禽流感H9亚型流行毒株间产生了较好的交叉保护力。用1998年分离的WD98株制备出的灭活疫苗对目前的流行毒株仍具有较好的保护效力。     

Serum and mucosal antibody responses and protection in pigs vaccinated against Mycoplasma hyopneumoniae with vaccines containing a denatured membrane antigen pool and adjuvant

Objective To investigate the protective efficacy of a pool of denatured membrane protein antigens of Mycoplasma hyopneumoniae (J strain) in the molecular size range 70 to 85 kDa (F3 antigen) in combination with adjuvants for pigs challenged with M hyopneumoniae .
Design A vaccine efficacy experiment with assessment of serum and respiratory tract antibody responses.
Procedure F3 antigens were emulsified with five different adjuvants. To groups of three pigs per vaccine, four vaccines were given by intramuscular injection, and two vaccines, including one of those given intramuscularly, were given by intraperitoneal injection.
Results Compared to six unvaccinated pigs, animals vaccinated with F3 antigen displayed significantly reduced pneumonia (54% reduction in mean lung score) following experimental challenge. Analysis of post-vaccination, pre-challenge IgG and IgA ELISA antibody absorbances in serum and respiratory tract washings revealed no correlation with lung score. Six weeks after challenge, pigs previously vaccinated intramuscularly mostly demonstrated greater IgG and IgA responses in respiratory tract washings, and greater IgG serum antibody responses, than those vaccinated by intraperitoneal injection.
Conclusion Pigs vaccinated with M hyopneumoniae antigens in the molecular size range of 70 to 85 kDa showed a significant reduction in lung lesions compared with unvaccinated control animals after experimental challenge. IgG and IgA antibody concentrations in serum and respiratory tract washings after vaccination do not provide a useful prognostic indicator of protection from enzootic pneumonia.     

In vivo evaluation of vaccine efficacy against challenge with a contemporary field isolate from the α cluster of H1N1 swine influenza virus

Influenza A virus vaccines currently contain a mixture of isolates that reflect the genetic and antigenic characteristics of the currently circulating strains. This study was conducted to evaluate the efficacy of a trivalent inactivated swine influenza virus vaccine (Flusure XP) in pigs challenged with a contemporary α-cluster H1N1 field isolate of Canadian swine origin. Pigs were allocated to vaccinated, placebo, and negative-control groups and monitored for respiratory disease for 5 d after challenge. On the challenge day and 5 d after challenge the serum of the vaccinated pigs had reciprocal hemagglutination inhibition antibody titers 40 for all the vaccine viruses but ≤ 20 for the challenge virus. Gross lesions were present in the lungs of all pigs that had been inoculated with the challenge virus, but the proportion of lung tissue consolidated did not differ significantly between the placebo and vaccinated pigs. However, the amount of virus was significantly reduced in the nasal secretions, lungs, and bronchoalveolar lavage fluid in the vaccinated pigs compared with the placebo pigs. These results indicate that swine vaccinated with Flusure XP were partially protected against experimental challenge with a swine α-cluster H1N1 virus that is genetically similar to viruses currently circulating in Canadian swine.     

Colostral and milk antibody titers in cows vaccinated with a modified live-rotavirus-coronavirus vaccine

Colostral and milk whey rotavirus (RV) and coronavirus (CV) antibody titers stimulated in 15 beef heifers by vaccination with a modified live-RV-CV vaccine were compared with titers in 15 nonvaccinated heifers. Geometric mean antibody titers to RV in colostral and 3-day milk whey from vaccinated heifers were 2,807 and 92, respectively, and in control heifers were 1,613 and 71, respectively. Geometric mean antibody titers to CV in colostral and 3-day milk whey of vaccinated heifers were 877 and 13, respectively, compared with titers were 877 and 13, respectively, compared with titers in nonvaccinated heifers of 731 and 7, respectively. Differences in antibody titers between vaccinated and nonvaccinated heifers were not significantly different.     

Use of an inactivated vaccine for prevention of parvovirus-induced reproductive failure in gilts

Gilts from dams that had been inoculated with inactivated porcine parvovirus (PPV) vaccine before breeding became seronegative to PPV by 26 weeks of age. Vaccination of these gilts with inactivated PPV vaccine at 32 weeks of age resulted in an antibody response that peaked at about 2 weeks after vaccination, with -log10 mean hemagglutination inhibiting (HI) antibody titers of less than 2. In the first-year group (82 gilts), HI titers gradually decreased, 20% of the gilts being seronegative by 6 to 7 weeks after vaccination and 75% being seronegative by 16 weeks after vaccination. In the second-year group, 93 gilts were infected naturally by a field strain of PPV at about 11 weeks after single vaccination with inactivated PPV. Additionally, in the second year, 20 vaccinated and 6 nonvaccinated gilts were immune-challenged with virulent PPV at 10 to 12 weeks after vaccination. Neither field nor challenge PPV infection of vaccinated pregnant gilts caused reproductive failure, even though some of the gilts became seronegative for PPV before challenge. Our findings suggest that single vaccination of gilts with inactivated PPV vaccine should give adequate protection from PPV-induced reproductive failure, even though serum HI titers decrease to an undetectable level shortly before PPV infection.