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Bulletin No. 12 - Fall 2002

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Summary

In this bulletin some interesting confirmation that heatstable toxins are the most frequent virulence factors in ETEC, and that C. difficile is playing a role in digestive disorders in neonates. Even if early vaccination schedules against M. hyopneumoniae are now controversial, vaccination was proved to be beneficial: a meta-analysis based on a large number of trials points out a 21-gram improvement of the ADWG, on an average. PCV2 and associated diseases are more and more spreading over the world. You'll find some initial report of them in Czech Republic, Greece and Japan and a the case of a rare form of PCV2-related exudative epidermitis in Sweden.

Contents

Bacterology
  • PCR Detection and identification of virulence factors from Escherichia coli strains causing neonatal diarrhea
  • Enterotoxigenic Escherichia coli infection in pigs and its diagnosis
  • Diagnosis and treatment of Clostridium difficile neonatal diarrhea
  • A meta-analysis comparing the effect of vaccines against Mycoplasma hyopneumoniae on daily weight gain in pigs
Virology
  • Herd-level seroprevalence of swine-influenza virus in Korea
  • Characterization of the carrier state in PRRSv infection
  • Identification of radically different variants of PRRSv in Eastern Europe: towards a common ancestor for European, American viruses
  • Association between clinical signs and high serum titers of PRRSv in nursery pigs under field conditions.
  • Evidence for local spread of PRRSv
  • First evidence of PCV-2 infection of pigs in the Czech Republic by semi-nested PCR
  • PCV-2 infection in swine fetuses inoculated at different stages of gestation
  • Detection of porcine circovirus types 1 and 2 in serum and tissue samples of pigs with and without postweaning multisystemic wasting syndrome
  • Exudative epidermitis and PCV-2 infection in a Swedish SPF-herd
  • First report of PMWS and PDNS in pigs in Greece
  • Detection of PCV-2 DNA by nested PCR from formalin-fixed tissues of PMWS pigs in Thailand
  • PDNS syndrome in Japan
Immunology
  • Immune regulation during pregnancy and host-pathogen interactions in infectious abortion
  • Dendritic cells: A specialized complex system of antigen presenting cells
  • Mucosal immunology: overview and potential in the veterinary species
  • Immunity in neonates

Bacterology

B085705
ROUILLARD T, LE GUENNEC J, MOALIC PY
PCR Detection and identification of virulence factors from Escherichia coli strains causing neonatal diarrhea
Rev M?d V?t 2002 153 : 261-268
ETEC (enterotoxigenic Escherichia coli) are the most common pathogens causing diarrhea in piglets. A PCR technique was used to test and identify the different virulence factors (STb, STa, LTa) produced by ETEC strains as well as the different fimbrial adhesins (K88, K99, F41, F107). ETEC strains were isolated mostly from the ileum of diarrheic piglets and also from their colon. The STb gene coding for the same toxin had the highest prevalence (30,5% of piglets) followed by STa (11.9%). The latter was always found associated with the fimbrial adhesin K99. Only K99 and K88 were detected with K88 as the most prevalent adhesin (12%). STb gene alone was detected in 22% of piglets. A majority of piglets were tested positive for 2 to 4 virulence factors. Previous studies showed similar results although they also reported a higher number of adhesins in ETEC strains.

FRANCIS DH.
Enterotoxigenic Escherichia coli infection in pigs and its diagnosis
J Swine Health Prod. 2002 10: 171-175
What is currently known about ETEC (enterotoxin Escherichia coli) is reported in this paper. The author considers different aspects of an ETEC infection: the role of fimbrial adhesins and enterotoxins, the relation between age, lineage and susceptibility to ETEC strains, the role of IMTGP (mucine-type sialoglycoprotein, the K88a and F18 receptor on porcine enterocyte) and the different methods of analysis (ELISA, IFA and PCR) with their flaws.

B085463
LEBRET A,
Diagnosis and treatment of Clostridium difficile neonatal diarrhea
Porc Magazine 2002 (355) : 71-73
Neonatal diarrhoea in piglets due to Clostridium difficile is becoming a major cause for concern in France. The pathogen is a well known causative agent of diarrhoea in humans but is relatively new in swine. In America, Clostridium difficile has been under close scrutiny and was the only pathogen detected in 29 % (year 2000) and 42% (year 2001) of piglets analysed and suffering from diarrhoea. The diarrhoea typically occurs in one week-old piglets and is characterized by yellowish liquid stool. There is a high morbidity rate among piglets but a relatively low mortality (10%). The infection is diagnosed by an ELISA test which detects A and B toxins in collected diarrhoea. To date, 3 types of treatment and preventive measures may be recommended: 1) yeasts administered to the sow or piglets which control the proliferation of the bacteria in the intestinal flora, 2) antibiotics such as bacitracin in America (no market authorization in France) and tiamulin in France which are being tested, 3) immunization of sows (oral administration of antitoxins and 'English soup', i.e. contamination of sows).

B085935
JENSEN CS, ERSBOLL AK, NIELSEN JP
A meta-analysis comparing the effect of vaccines against Mycoplasma hyopneumoniae on daily weight gain in pigs
Prev Vet Med 2002 54 : 265-278
A meta-analysis was conducted in order to assess the effects of vaccination against a causative agent of swine enzootic pneumonia (Mycoplasma hyopneumoniae) on ADWG (average daily weight gain). The three commercial vaccines currently available against the infectious agent are Stellamune?, Suvaxyn? and Hyoresp?. Out of the sixty-three studies published, 14 were finally kept for analysis as they met all the inclusion criteria. The variables of the meta-analysis were ADWG, trial, treatment, trial size, vaccination status, housing system and vaccination schedule. An average 21g increase in ADWG was calculated in vaccinated pigs compared to non vaccinated pigs. Other variables had no significant impact on ADWG.

Virology

B085688
JUNG T, CHOI C, CHUNG HK, KIM J, CHO WS, JUNG K, CHAE C -
Herd-level seroprevalence of swine-influenza virus in Korea
Prev Vet Med 2002 53 : 311-314
KOREA, SWINE, SWINE INFLUENZA, SWINE INFLUENZA VIRUS, SURVEY, EPIDEMIOLOGY, SEROLOGY, ELISA
A nationwide survey was carried out in Korea to assess the seroprevalence of one subtype of swine influenza A virus: H1N1 virus in swine herd. An ELISA kit was used to test the 911 sera from finishing pigs in 130 swine farms covering the five country states. The results showed a high prevalence of the virus (93 out of the sampled herds were positive and a herd was considered positive if at least two of the sampled animals were positive), even higher than the virus prevalence reported in America and Denmark.

B085469
HORTER DC, POGRANICHNIY RM, CHANG CC, EVANS RB, YOON KJ, ZIMMERMAN JJ IOWA STATE UNIV SCI & TECHNOL
Characterization of the carrier state in porcine reproductive and respiratory syndrome virus infection
Vet Microbiol 2002 86 : 213-228
An experimental study was conducted to determine the carrier status of PRRSV infected pigs over a long period of time (105 days). PRRSV is known to produce persistent infection and the evaluation of the carrier state is useful for the protection of negative herd, the prevention and control of the disease. PRRS-free pigs (60) were intranasally inoculated with a virus supernatant. A control group (60) was kept for comparison. Various samples (serum, peripheral blood leucocyte, oropharyngeal scrapings,..) from animals were collected at different days PI (post-infection) and assayed for conversion to PRRS by VI (virus isolation) RT-nPCR (transcriptase-nested polymerase chain reaction) and swine bioassay. Virus antibody response was tested with an ELISA kit. The VI and swine bioassay results showed that 51 out the 59 virus-inoculated animals were PRRS virus carrier over the whole study period. The eight remaining pigs were positive for viral nucleic acid by RT-nPCR. However no difference in antibody response between carrier and non carrier was noted with ELISA. Consequently, reliable identification of carriers may be performed using the first three techniques but not ELISA.

B085923
STADEJEK T, STANKEVICIUS A, STORGAARD T, OLEKSIEWICZ MB, BELAK S, DREW TW, PEJSAK Z
Identification of radically different variants of porcine reproductive and respiratory syndrome virus in Eastern Europe: towards a common ancestor for European, American viruses
J Gen Virol 2002 83 : 1861-1873
Previous studies have reported the genetic diversity of EU-type PRRSV. This is confirmed by a new study involving two Eastern European strains from Poland and Lithuania. A total of 22 ORF5 segments of PRRSV from Poland, Germany, Great-Britain and Lithuania were sequenced as well as two EU-type live vaccines. Similarly, the ORF7 sequences of Polish and Lithuanian strains were determined. It was found that the Polish and especially the Lithuanian PRRSV ORF5 sequences were exceptionally diverse from any other European genotype. Also, the size of the ORF7 protein from Lithuanian PRRSV was intermediate between the European prototype (Lelystad virus) and the US-type ORF7 protein, thereby establishing a link between EU-US sequences and suggesting a probable evolution from a common ancestor.

CUARTERO L. DEE S, DEEN J, RUIZ A, PIJOAN C
Association between clinical signs and high serum titers of porcine reproductive and respiratory syndrome virus (PRRSV) in nursery pigs under field conditions
J Swine health Prod. 2002, 10: 119-122
The acclimatization of gilts is considered a good strategy to prevent a PRRS outbreak in a PRRS positive herd. A cross-sectional study was carried out with 120 pigs (2, 4, 6 weeks of age) from a herd experiencing PRRSV. Pigs were classified into for 4 categories (healthy pigs, healthy pigs with lymphadenopathy, sick pigs and sick pigs with lymphadenopathy) according to their clinical signs. Their antibody titers were also recorded. The main conclusion of the study was that pigs showing clinical signs of PRRSV and potentially serving as PRRSV source for gilt acclimatization were not necessarily viremic.

LAGER KM, MENGELING WL, WESLEY R
Evidence for local spread of porcine reproductive and respiratory syndrome virus
J Swine Health Prod. 2002, 10: 167-170
Indirect transmission of PRRSV in several herds had been previously reported. In a recent study, PRRSV was isolated in 25 isolates from seven local herds in north-east Iowa. The isolates were subsequently analysed by RFLP (restriction fragment length analysis) and a similar RFLP pattern was revealed in 6 out of the seven farms which were run independently from one another. An indirect area spread of the virus was concluded but the mode of transmission is yet to be discovered.

B085677
CELER V, CARASOVA P
VET & PHARMACEUT UNIV BRNO
First evidence of porcine circovirus type 2 (PCV-2) infection of pigs in the Czech Republic by semi-nested PCR
J Vet Med B Infect Dis Vet P 2002 49 : 155-159
PCV-2 was detected in 37 out of 77 samples from inguinal lymph nodes and nasal swabs from Czech pigs by using a semi-nested PCR with a first and second round of amplification. PMWS had been diagnosed in a number of pigs providing 56 samples and it turned out that the samples from the pigs with the clinical disease were highly positive for PCV-2. The results of the first round were confirmed by a second re-amplification which detected the presence of PCV-2 DNA only in three more samples. DNA sequencing was then carried out to further confirm the specificity of the PCR test.

B085961
SANCHEZ RE, NAUWYNCK HJ, MCNEILLY F, ALLAN GM, PENSAERT MB
Porcine circovirus 2 infection in swine fetuses inoculated at different stages of gestation
Vet Microbiol 2001 83 : 169-176
The aim of the present study was to verify whether PCV-2 can replicate in fetal tissues and cause damage to fetuses. Two fetuses were inoculated with PCV-2 in each of two seropositive sows (out of the 6 sows included) and the remaining fetuses were left uninoculated. Inoculation was performed at different dates (57, 75, 92 days of gestation). The results showed that PCV-2 was isolated from all PCV-2 inoculated foetuses. Serum, lung, heart, liver, spleen, kidney, lymph node samples collected were PCV-2 positive in all foetuses. However, infected cells were more numerous in fetuses inoculated at 57 d. than other fetuses. Also, lesions were observed only in the four fetuses inoculated at 57 d. The non-inoculated fetuses were seronegative. Evidence of a possible viral replication of the virus and subsequent damage to fetuses caused by the infection was thus brought. The gestational age was an important parameter in the extent of PCV-replication.

B085668
CALSAMIGLIA M, SEGALES J, QUINTANA J, ROSELL C, DOMINGO M
UNIV AUTONOMA BARCELONA
Detection of porcine circovirus types 1 and 2 in serum and tissue samples of pigs with and without postweaning multisystemic wasting syndrome
J Clin Microbiol 2002 40 : 1848-1850
Two major techniques (PCR and in situ hybridization) for PCV1 and PCV2 detection were compared in terms of sensitivity. Serum samples were tested by PCR and superficial inguinal lymph nodes from PMWS-free and PMWS affected pigs were examined by the two techniques. Generally, over 50% of samples were found positive for PCV-2. PCV-1 was detected in only three samples. PCR proved to be a more sensitive technique although both methods achieved high agreement. On the other hand in situ hybridization was more efficient in detecting the presence of PMWS microscopic lesions.

B085577
WATTRANG E, MCNEILLY F, ALLAN GM, GREKO C, FOSSUM C, WALLGREN P
SWEDISH UNIV AGR SCI
Exudative epidermitis and porcine circovirus-2 infection in a Swedish SPF-herd
Vet Microbiol 2002 86 : 281-293
An unexpected outbreak of Exudative Epidermatitis (EE) occurred in a SPF-herd in Sweden in 1993. A survey over 10 year (1990-2000) was carried out in order to find the probable cause of the infection. This SPF-herd was started in 1988 and remained closed to new animal material except semen (Artificial Insemination). Serum samples from pigs were retrospectively tested as well as samples from three sows which farrowed after the initial EE outbreak and from their offspring. Their clinical signs were also monitored. Samples were tested for Staphylococcus hyicus (the causative agent of EE), as well as presence of antibody to PCV-2 (interferon-a and interleukin-6). Until Feb. 1993, the SPF-herd was PCV-2 negative. In the time of outbreak, the pigs had varying levels of PCV-2 and piglets showed seroconversion later during 1993. The AI boars from which semen was collected were also sero-positive to PCV-2. S. hyicus was isolated from all pigs prior to the outbreak. One piglet showed clinical signs of EE and 14 others had IFN-a in their serum, an indicator of viral activity. Based on the results of the study, it was concluded that the introduction of PCV-2 was a predisposing factor initiating EE skin lesions and reproductive disturbance.

B085765
SAOULIDIS K, KYRIAKIS SC, KENNEDY S, LEKKAS S, MILIOTIS CC, ALLAN G, BALKAMOS GC, PAPOUTSIS PA
ARISTOTLE UNIV THESSALONIKI
First report of post-weaning multisystemic wasting syndrome and porcine dermatitis and nephropathy syndrome in pigs in Greece
J Vet Med B Infect Dis Vet P 2002 49 : 202-205
The first cases of PMWS and PDNS associated to PCV-2 in Greece are reported in this paper, with a detailed description of characteristic clinical signs, post-mortem and histopathological findings.

B085762
KIATIPATTANASAKULBANLUNARA W, TANTILERTCHAROEN R, SUZUKI K, ALBARENQUE SM, THANAWONGNUWECH R, NAKAYAMA H, DOI K
Detection of porcine circovirus 2 (PCV-2) DNA by nested PCR from formalin-fixed tissues of post-weaning multisystemic wasting syndrome (PMWS) pigs in Thailand
J Vet Med Sci 2002 64 : 449-452
Detection of PCV-2 in 16 formalin-fixed paraffin-embedded (FFPE) or formaline-fixed (FF) tissues from PMWS pigs was performed by a first PCR amplification and by the second nested PCR in Thailand as part of a retrospective study (tissues dating from 1993-2000). The second technique was the most sensitive one to detect the virus in all FFPE and FF samples from all pigs with PMWS.

B085530
ABE T, YAMADA M, HARITANI M, TANIMURA N, KIMURA KM, KAWASHIMA K
KAMOJIMA LIVESTOCK HYG CTR
Porcine dermatitis and nephropathy syndrome in Japan
Vet Rec 2002 150 : 87-88
A detailed account of the first case of PDNS in Japan, with description of macroscopical and microscopical lesions is given in this paper.

Immunology

B085669
ENTRICAN G,
MOREDUN RES INST
Immune regulation during pregnancy and host-pathogen interactions in infectious abortion
J Comp Pathol 2002 126 : 79-94
This paper is an in-depth study into the immune mechanisms involved in the success and/or failure of pregnancy in mammal and human beings both in terms of fetal and maternal survival. The role of immune cells in the context of infectious abortions is also considered. The study highlights the beneficial or detrimental effects of cytokines as well as the effects of hormones on normal pregnancy and infection occurring during pregnancy.

B085618
MAKALA LHC, NAGASAWA H -
OBIHIRO UNIV AGR & VET MED
Dendritic cells: A specialized complex system of antigen presenting cells
J Vet Med Sci 2002 64 : 181-193
The current knowledge on the complex system of dendritic cells (DC) is reviewed in this paper. DC are key elements in the immune system and they are known to capture antigens, process them and present them to the na?ve T cells for activation. The ontogeny, classification, morphology and function of the DC are detailed but much remains to be discovered about the mechanisms involved in immune response and the role of DC. Research into the network of DC is underway worldwide.

B085743
HANNANT D,
ANIM HLTH TRUST
Mucosal immunology: overview and potential in the veterinary species
Vet Immunol Immunopathol 2002 87 : 265-267
The importance and role of mucosal immune system has been studied in several animal species, especially in horses and are summed up in this paper.

B085739
MOREIN B, ABUSUGRA I, BLOMQVIST G
NATL VET INST
Immunity in neonates
Vet Immunol Immunopathol 2002 87 : 207-213
The immature immune system of neonates and the passive immunity acquired from the mother are problematic in terms of an active immune response which should be mounted by neonates in case of infection. In addition, the neonatal innate immune system presents some defects and is orientated towards an up regulation of Th2 response and a deficiency of Th1. However several experiments with mice have shown that the TH2 bias can be overcome with induction of Th1 by appropriate treatment and vaccination.



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