A Salmonella abortusovis inactivated vaccine protects mice from abortion after challenge.

Two types of Salmonella abortusovis vaccines were prepared, one with aluminium hydroxide (vaccine A) and the other with water in oil (vaccine B) adjuvants. They were compared in a pregnant mouse model, aiming at protecting them from abortions after challenge with a virulent strain of S. abortusovis. The protection for vaccine A was from 74% to 77.6% and that for vaccine B from 71% to 79.6%. Abortions occurred 5-10 days post challenge and S. abortusovis was isolated from all aborted fetuses and from the liver and the spleen of their mothers at the end of the experiment (18 days post challenge). The presence of salmonella in the liver and the spleen of vaccinated non-pregnant but challenged mice was studied in a separate experiment. The bacterium was isolated from one out of 12 vaccinated mice 6 days post challenge as well as from the six controls.     

Leptospiral infection in aborted equine foetuses

During an investigation of equine abortion, leptospiral infection was demonstrated in nine out of 22 foetuses examined by immunofluorescence and culture. Strains belonging to four serogroups (Australis, Pomona, Hebdomadis and Icterohaemorrhagiae) were isolated. The age of leptospira infected foetuses ranged from six months to term.     

A systematic review of leptospirosis on dogs,pigs, and horses in Latin America

Leptospirosis is a worldwide zoonosis which can affect many species. Control programs need accurate diagnosis to be successful, and currently, diagnosis relies on serology. It presents three main issues: the sampling, the antigen panel, and the cutoff point. Herein, we propose a systematic review on leptospirosis among dogs, pigs, and horses in Latin America in order to improve the understanding of the seroepidemiology of leptospirosis in these species in the region as well as the temporal development of the research on this topic and, consequently, improve the chances of success on control programs. Internet databases were consulted over 2015. Inclusion criteria included serosurvey using MAT; a relevant number of animals; the presence in the antigen panel of at least one representative of serogroups Icterohaemorrhagiae and Canicola for dogs, Icterohaemorrhagiae, Australis, and Pomona for pigs, and Icterohaemorrhagiae and Australis for horses; and a cutoff point of ≥100. Overall, 240 papers were studied, of which 87 referred to dogs, 66 to pigs, 39 to horses, and 48 to more than one of the studied species. In relation to those that met all the inclusion criteria, it was 45 (66.2%) in dogs, 23 (41.8%) in pigs, and 23 (63.9%) in horses. Leptospirosis is widespread in Latin America. Predominant serogroups are Canicola to dogs and Icterohaemorrhagiae to pigs and horses. Therefore, research on animal leptospirosis should be encouraged in Latin America, in order to reach a greater standardization in studies and then achieve better results on control programs.     

Occurrence of leptospiral infections in swine population in Poland evaluated by ELISA and microscopic agglutination test

Swine are one of significant reservoirs and sources of Leptospira infections for man. Serological screenings help to effectively control the epidemiological situation in swine herds and to prevent transmission of Leptospira from animals to man. The purpose of this study was to investigate, by the use of serological methods, the prevalence of infections caused by selected Leptospira serogroups in swine population in Poland. A total of 7112 swine serum samples were examined. The samples were collected from January to October 2008 and came from 280 counties situated in all 16 provinces of Poland. All sera were examined preliminary by enzyme-linked immunosorbent assay (ELISA) using heat-stable antigenic preparation. The samples positive or doubtful in ELISA were investigated by microscopic agglutination test (MAT) with use of serovars Icterohaemorrhagiae, Pomona, Canicola, Sejroe, Tarassovi and Of the collected sera examined by ELISA 73 (1.02%) samples were positive, 85 (1.20%)--doubtful and 6954--negative. Among ELISA-positive and doubtful sera 64 samples (coming from 14 provinces) were recognized in MAT as positive. Among MAT positive samples 42.19% of sera demonstrated titres with serovar Pomona, 32.81%--with Sejroe, 14.06%--with Icterohaemorrhagiae, 6.25%--with Tarassovi, 3.13%--with Grippotyphosa and 1.56% with Canicola.     

Canine leptospirosis—Do we have a problem?

Acute canine leptospirosis is well known to vet surgeons. To protect dogs against this lethal disease, vaccination is widely used. However, chronic forms of leptospirosis have been noticed even in vaccinated animals, generally induced by bacteria from serogroups other than Icterohaemorrhagiae and Canicola such as Sejroë, Australis or Grippotyphosa. In a survey on 98 ill cats, 48% were positive in microagglutination test (MAT) to Leptospira spp., showing that this infection is also frequent in the feline species.     

Prevalence of serum antibodies against six Leptospira serovars in healthy dogs

OBJECTIVE: To determine the prevalence of antibodies against 6 Leptospira serovars and determine risk factors associated with positive Leptospira titers in healthy client-owned dogs in Michigan. DESIGN: Cross-sectional study. ANIMALS: 1,241 healthy dogs at least 4 months of age. PROCEDURES: Dogs were examined by veterinarians at private practices. Vaccinated and unvaccinated dogs were enrolled in the study, which occurred prior to the availability of a 4-serovar (Canicola, Grippotyphosa, Icterohaemorrhagiae, and Pomona) Leptospira vaccine. Sera were tested by use of the microscopic agglutination test to determine antibody titers against Leptospira serovars Bratislava, Canicola, Grippotyphosa, Hardjo, Icterohaemorrhagiae, and Pomona. A questionnaire was used to collect demographic information about each dog to identify risk factors associated with seropositive status. RESULTS: 309 of 1,241 (24.9%) dogs had antibody titers against at least 1 of the 6 Leptospira serovars, which suggested exposure to Leptospira spp. Prevalence of antibodies was highest to serovar Grippotyphosa, followed by Bratislava, Canicola, Icterohaemorrhagiae, and Pomona. Age, travel outside Michigan, exercise outside fenced yards, and exposure to livestock and wildlife were significant risk factors for positive titers. CONCLUSIONS AND CLINICAL RELEVANCE: Among healthy dogs from the lower peninsula of Michigan, > 20% have antibodies against leptospiral serovars historically considered uncommon but more recently incriminated as causing clinical canine leptospirosis. Wildlife and livestock may be of increasing importance as reservoirs for canine leptospirosis as urbanization continues to occur. Expanded vaccination strategies may partially mitigate these trends.     

Evaluation of colostral immunity in swine with commercial anti-leptospira polyvalent whole-bacteria vaccine

The intensity and duration of passive immunity against swine leptospirosis were investigated by the microscopic agglutination test and in vitro leptospira growth inhibition. Twenty-one females at first parturition were divided into three groups: Group A (n=08): received two doses with 30 days interval of the commercial anti-leptospira bacterin A. Group B (n=06) received two doses with 30 days interval of the commercial anti-leptospira bacterin B and Group C (n=07) was the control. In all groups the colostrums were collected. Blood collection of piglets was performed in four different ages. Agglutinin antibodies were equally detected in sera and colostrums for serovars Canicola, Grippotyphosa, Copenhageni, Icterohaemorrhagiae and Pomona (Group A) and Canicola, Copenhageni, Icterohaemorrhagiae, Pomona and Hardjo (Group B). Mean neutralizing antibodies titers were low. Passive immunity was low duration.     

Leptospires isolated from wild mammals caught in the south west of England.

Leptospires of the serogroups Australis, Icterohaemorrhagiae, Hebdomadis, Javanica and Pomona were isolated from wildlife caught in the south west of England.     

Leptospira spp. in horses in southern Brazil: Seroprevalence,infection risk factors,and influence on reproduction

Leptospirosis in horses is often associated with reproductive disorders. In the southern states of Brazil, horses are used for various jobs and cultural practices; nevertheless, serological surveillance for Leptospira is rare. Therefore, the objective of this study was to determine the seroprevalence of Leptospira spp. in horses in southern Brazil, as well as to identify the risk factors for infection and its impacts on reproduction. We performed microscopic agglutination tests for 12 serovars that corresponding 9 serogroup (Sejroe, Icterohaemorrhagiae, Australis, Pyrogenes, Pomona, Canicola, Grippotyphosa, Tarassovi and Ballum) in 595 samples from 60 herds. A brief history was obtained to analyze risk factors for reproductive disorders. A total of 45.9% of the tested horses were seropositive, of which the most frequent serogroups were Icterohaemorrhagiae (Icterohaemorrhagiae and Copenhageni serovars) and Ballum (Ballum serovar). Simple infections were found in 45.4% of seropositive animals, while mixed infections occurred in 54.6% of horses. There was a correlation between seropositivity and age and sex, that is, seropositivity was more frequent in animals over 6 years old and in females. There was no correlation between seropositivity and reproductive disorders. We conclude that there is a high seroprevalence of Leptospira spp. in southern Brazil with predominance of Icterohaemorrhagiae serogroup, mainly in older animals. Location, breeds, contact with dogs or other domestic animals are not risk factors, whereas gender is a risk factor. Reproductive disorders are not due to leptospirosis in the study region.     

Experimental infection of pregnant gilts with Leptospira interrogans serovar mozdok.

Three pregnant gilts were experimentally infected with leptospires of the serovar mozdok, isolated from an aborted pig fetus from a Portuguese pig farm with abortion problems. All the gilts aborted dead or dying piglets on days 105 or 106 of pregnancy. Serovar mozdok was isolated from 12 of the 22 piglets in the three litters. Histological examination of the livers and kidneys of the gilts at the end of the experiment revealed evidence of disease, and leptospires were isolated from their kidneys. Their serological responses up to 42 days after inoculation were monitored by means of a microscopic agglutination test, using 21 antigens from 18 serogroups. Cross reactions to heterologous antigens belonging to the Grippotyphosa, Australis, Icterohaemorrhagiae and Cynopteri groups were observed in all of them.     

水禽用H5亚型禽流感灭活疫苗对高致病性禽流感病毒流行毒株的免疫保护效果研究

为评价水禽用禽流感灭活疫苗(H5N2亚型,D7株)对2010年以后分离的高致病性禽流感病毒流行毒株的免疫保护效果,将该疫苗免疫3周龄SPF鸭后,21 d采血、分离血清测定HI抗体效价,同时用5株2010年以后分离的高致病性禽流感流行毒进行攻毒保护试验,攻毒后5d采集所有试验鸭喉头和泄殖腔拭子进行病毒分离.结果显示,该疫苗免疫SPF鸭21 d后的HI抗体效价的几何平均滴度达7.4log2,对5株高致病性禽流感病毒的攻击均可产生良好的免疫保护,并有效阻止病毒排泄.该疫苗的推广使用将对我国水禽高致病性禽流感的防控发挥重要作用.     

Reactivity of heat-stable Leptospira antigenic preparation used in enzyme-linked immunosorbent assay for detection of antibodies in swine serum

Serology plays an important role in laboratory diagnosis of leptospirosis. Apart from the most often used microscopic agglutination test (MAT), enzyme-linked immunosorbent assay (ELISA) seems to be useful especially in screenings of animal herds. The ELISA used for detection of antibodies against selected Leptospira serogroups in swine serum samples was investigated during the study. An essential element of this test is heat-stable antigenic preparation from cultures of Leptospira interrogans serovars Icterohaemorrhagiae, Pomona and L. borgpetersenii serovar Sejroe. The aim of the present study was to identify and analyze ELISA heat-stable antigen fractions playing a role in the reaction with leptospiral antibodies indicated in swine serum. Reactivity of the three-component antigenic preparation was compared in immunoblotting with reactivity of six heat-stable antigenic preparations made from the following single serovars: L. interrogans serovars Icterohaemorrhagiae, Pomona, Canicola, L. borgpetersenii serovars Sejroe, Tarassovi and L. kirshneri serovar Grippotyphosa. All antigenic preparations were submitted to SDS-PAGE and transferred to a nitrocellulose membrane using a semidry system. After the transfer, the membrane was incubated with diluted swine serum containing antibodies specific for one of the six above mentioned Leptospira serovars. For the three-component antigenic preparation and antigens prepared from single serovars the immunoblot revealed reaction of sera with fractions of the 20-26 kDa region and around the 14.5 kDa region. The investigated heat-stable Leptospira antigenic preparation contains fractions demonstrating serogroup- and species-specificity. Fraction 20-26 kDa showed serogroup-specific activity, whereas the fraction around 14.5 kDa showed species-specific activity.     

Seroepidemiology of leptospirosis in livestock in Trinidad

A study was conducted to determine the seroprevalence of leptospirosis and infecting serovars across livestock (cattle, sheep, goats, and pigs) in Trinidad using the microscopic agglutination test with an international panel of 23 serovars. Of a total of 590 cattle tested, 21.5% were seropositive with agglutinations to 13 of the 23 antigens used in the panel. Icterohaemorrhagiae (9.3%), Sejroe (4.1%), Ballum (4.1%), and Autumnalis (1.9%) were the predominant serogroups detected in the cattle sampled (n = 590). Of 222 sheep tested, 5.0% were seropositive with agglutinations to five serovars belonging to two serogroups. These serogroups were Autumnalis at 2.7%, and Icterohaemorrhagiae at 2.3% of all sheep tested (n = 222). Of a total of 180 goats tested, 3.3% were seropositive, all agglutinating to the Icterohaemorrhagiae serogroup, 1.7% to serovar Copenhageni, 1.1% to serovar Mankarso, and 0.6% to serovar Icterohaemorrhagiae. Among pigs (n = 200), 5.0% were seropositive for five serovars belonging to three serogroups. These serogroups were Icterohaemorrhagiae at 2.5%, Australis at 2%, and Ballum at 0.5%. Overall, age and sex of animals were not significantly associated with leptospirosis with the exception of cattle where age was a significant factor for seropositivity. It was concluded that for livestock, leptospirosis may be an important zoonotic and economic disease, particularly in the case of cattle. It is imperative that the impact of leptospirosis on abortion, stillbirths, and decreased milk production in livestock in the country be assessed.     

Epidemiology of leptospirosis in North-Central Italy: Fifteen years of serological data (2002–2016)

Leptospirosis is a re-emerging bacterial zoonosis. North-Central Italy is characterized by a geographic area that promote Leptospira circulation. Data on sero-epidemiological survey carried out from 2002 to 2016 in North-Central Italy were reported and discussed. Overall, 709 out of the 8488 (8.35%) tested sera were positive for Leptospira at the cut-off titer (1:100) and 218 (2.57%) at higher titer (≥1:400). The highest percentages of positivity was recorded for coypus (22.86%), swine (19.74%) and bovine (13.03%). Pomona and Australis resulted the serogroup more often detected, followed by Sejroe and Icterohaemorrhagiae; while, a low number of positive sera was detected for serogroups Ballum, Canicola and Tarassovi. Percentage of positive sera for each year slightly decreased from 2002 to 2008 and rose from 2009. High percentages of positive reactions were recorded in 2014 (17.23%), 2015 (19.61%) and 2016 (38.05%). In conclusion, the results of this investigation reported an increase of leptospirosis in North-Central Italy. Furthermore, several animals resulted infected as accidental hosts by unusual Leptospira serovars. These data could suggest a change in host range for some serovars, that may promote the adaptation to new hosts.     

Prevalence of Leptospira infection in aborted pigs in Northern Ireland

During an investigation of pig abortions and stillbirths in Northern Ireland, leptospires were isolated from 55 of the 78 litters examined. Strains belonging to four serogroups (Australis, Icterohaemorrhagiae, Hebdomadis and Autumnalis) were recovered but leptospires of the Australis serogroup accounted for 91 per cent of the isolates. Two serovars of the Australis group bratislava and muenchen, were identified.     

A serological survey of antibodies to Leptospira species in dogs in South Africa

Leptospirosis, a disease more common in the tropics, can cause a life-threatening multisystemic syndrome in humans and animals. Immunity, whether natural or vaccine-induced, is serogroup-specific with the infecting serovars varying according to geographical locality. In South Africa, in spite of the fact that the bacterin vaccine for some Leptospira serovars is often used, there is no recent information on the incidence of canine leptospirosis as well as the infecting serovar/s. The aim of this study, which was undertaken on sera collected in 2008 and 2009 from both strays and owned dogs predominantly in the coastal regions of South Africa, was to determine the presence of leptospiral antibodies to 15 serovars known to infect dogs. Of the 530 samples tested, 25 tested positive to 7 different serovars with the microscopic agglutination test (MAT). Nine of the 25 samples tested positive to more than one serovar. The 2 serovars most frequently represented were Canicola, which reacted to 17 sera, and Pyrogenes, which reacted to 10 sera. Currently the only vaccines available in South Africa in different combinations contain serovars Canicola, Icterohaemorrhagiae, Pomona and Grippotyphosa. The results showed that the use of vaccines containing serovar Canicola is still justifiable in certain regions of the country. However, the presence of antibodies to serovar Pyrogenes in several dogs, pending a broader investigation, indicates that this serovar should also be included in the range of Leptospira vaccines for use in South Africa.     

禽大肠杆菌病免疫保护机理的研究

以禽病原性大肠杆菌O18、O78分离株制成超声波裂解铝佐剂灭活苗免疫14日龄鸡，以相同或不同外膜蛋白型（Outer membrane protein pattern,OMP型）的O18、O78分离株攻毒。结果表明：O78血清相同和不同OMP型分离株间能获得最大保护；O18血清型相同OMP型分离株间获得最大保护，而不同OMP型分离株间不能保护；上述两个血清型的分离株间不论OMP型是否相同，均缺乏保护。以间接ELISA试验、间接血凝试验分别测定了试验鸡临攻毒前针对大肠杆菌OMPs和脂多糖(Lipopolysaccharide,LPS）的抗体。结果表明：免疫组鸡血清上述两种抗体明显高于攻毒对照组；在免疫组，存活鸡临攻毒前血清中上述两种抗体滴度恒高于死亡鸡，但除3个组外，多数组差异不显著。攻毒对照组这一关系不稳定。结果说明：禽大肠杆菌疫苗的免疫保护，主要与O血清型有关，部分与OMP型有关，如O18分离株，免疫保护性抗原含OMPs,LPS等多个抗原表位。     

Production of a falcon herpesvirus vaccine.

Ten common kestrels (Falco tinnunculus) were used for this falcon herpes vaccine experiment. Four kestrels were subcutaneously given 1 ml of an attenuated falcon herpesvirus that had originally been isolated from the liver of an American prairie falcon (Falco mexicanus). This virus was then passaged 100 times on chicken embryo fibroblast cells (CEF-cells). Another 4 kestrels were given subcutaneously an inactivated falcon herpesvirus vaccine derived from the same American field strain. This vaccine was concentrated, inactivated by heat and betapropiolactone and emulsified in complete Freund's adjuvans. Two further kestrels served as controls and were not vaccinated. Twenty-one days after vaccination, all 10 kestrels were challenged with passage 3 of the American falcon herpesvirus. The 2 control kestrels died 6 days after challenge and 3 of those given the inactivated herpes vaccine died 9 days after challenge, with typical lesions of herpesvirus inclusion body hepatitis. Before the vaccination experiment, all 10 kestrels were free of serum neutralising antibodies to the falcon herpesvirus. Twenty-one days after vaccination, all 4 kestrels vaccinated with the attenuated vaccine, and one vaccinated with the killed vaccine, had seroconverted, having shown no symptoms to the challenge with a low passage virulent American herpesvirus strain. Following the challenge their antibody titres to falcon herpesvirus increased. No herpesvirus was isolated from any of the cloacal swabs taken during this experiment, indicating that there is no danger for any other birds from the attenuated herpesvirus vaccine. This experiment clearly shows that an attenuated falcon herpesvirus vaccine can protect kestrels from fatal inclusion body hepatitis.     

Evaluation of factors affecting vaccine efficacy of recombinant Marek's disease virus lacking the Meq oncogene in chickens

We previously reported that deletion of the Meq gene from the oncogenic rMd5 virus rendered it apathogenic for chickens. Here we examined multiple factors affecting Marek's disease vaccine efficacy of this nonpathogenic recombinant Meq null rMd5 virus (rMd5deltaMeq). These factors included host genetics (MHC haplotype), strain or dose of challenge virus, vaccine challenge intervals, and maternal antibody status of the vaccinated chicks. Studies on host genetics were carried out in five chicken lines comprising four different MHC B-haplotypes. Results showed that chicken lines tested were highly protected, with protective indexes of 100% (B*2/*15), 94% (B*2/*2), 87% (B*19/*19), and 83% (B*21/*21). At a challenge dose above 8000 plaque-forming units, differences in protection were observed between the two highly virulent strains examined (648A and 686). The interval between vaccination and challenge indicated a protective efficacy from 0 to 2 days varied greatly (12%-82%) after challenge with vv+686, the most virulent virus. Less variation and significant protection began at 3 days post vaccination and reached a maximum at 5 days post vaccination with about 80%-100% protection. Taken together, our results indicate that the factors examined in this study are important for vaccine efficacy and need to be considered in comparative evaluations of vaccines.