Maria Pieters

Publications (4)8.88 Total impact

• Article: An experimental model to evaluate Mycoplasma hyopneumoniae transmission from asymptomatic carriers to unvaccinated and vaccinated sentinel pigs.

  Maria Pieters, Eduardo Fano, Carlos Pijoan, Scott Dee
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  ABSTRACT: The objective of this study was to determine the effect of vaccinating susceptible animals on the transmission of Mycoplasma hyopneumoniae from experimentally infected pigs during the chronic phase of infection. Thirty-six seeder pigs were experimentally infected with M. hyopneumoniae. Eighty and 200 d post-infection (dpi) 18 seeder pigs were placed in direct contact with 15 vaccinated and 15 unvaccinated age-matched naïve animals. Direct animal contact occurred over 14 d. Pigs were euthanized at the end of the contact period and bronchial swabs were collected and lung tissue examined. At 94 dpi, 15 out of 15 unvaccinated sentinels and 14 out of 15 vaccinated sentinels tested positive for M. hyopneumoniae by nested polymerase chain reaction (N-PCR). At 214 dpi, M. hyopneumoniae DNA was detected by PCR in 8 out of 15 unvaccinated and 6 out of 15 vaccinated sentinels. Vaccination against M. hyopneumoniae did not prevent colonization of sentinels in contact with infected animals. Transmission of M. hyopneumoniae from asymptomatic carriers to unvaccinated and vaccinated sentinels was not different.
  Canadian journal of veterinary research = Revue canadienne de recherche vétérinaire 04/2010; 74(2):157-60. · 0.94 Impact Factor
• Article: An assessment of the duration of Mycoplasma hyopneumoniae infection in an experimentally infected population of pigs.

  Maria Pieters, Carlos Pijoan, Eduardo Fano, Scott Dee
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  ABSTRACT: Mycoplasma hyopneumoniae (M. hyopneumoniae) is the primary pathogen of enzootic pneumonia (EP), a highly prevalent respiratory disease that affects pigs worldwide. Previous studies have demonstrated that M. hyopneumoniae infection can be longer than 185 days; however, the total duration of infection has not been determined yet. Therefore, the objective of this study was to determine the duration of M. hyopneumoniae infection in asymptomatic carriers. To achieve our goal, 60 pigs were inoculated with M. hyopneumoniae strain 232 and the persistence of M. hyopneumoniae in the respiratory tract was assessed by detection of the bacterial DNA in bronchial swabs and the ability of the infected pigs to transmit the pathogen to sentinels. Infection of the inoculated animals was demonstrated by the detection of M. hyopneumoniae DNA in nasal swabs, seroconversion to the bacteria and the onset of dry coughing. Experimentally infected pigs shed M. hyopneumoniae prior to and after the cough was observed. M. hyopneumoniae DNA was detected in 100% of experimentally infected pigs at 94 days post infection (dpi), 61% at 214dpi and 0% at 254dpi. Experimentally infected pigs transmitted the bacteria to sentinels at 80 and 200dpi. Results of this study have demonstrated that M. hyopneumoniae infected pigs can be incubatory as well as convalescent carriers of the pathogen and that convalescent carriers can remain infectious for up to 200 days. Total clearance of M. hyopneumoniae in the group was evidenced, demonstrating that duration of M. hyopneumoniae infection lasts less than 254 days.
  Veterinary Microbiology 09/2008; 134(3-4):261-6. · 3.33 Impact Factor
• Article: Current perspectives on the diagnosis and epidemiology of Mycoplasma hyopneumoniae infection.

  Marina Sibila, Maria Pieters, Thomas Molitor, Dominiek Maes, Freddy Haesebrouck, Joaquim Segalés
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  ABSTRACT: Mycoplasma hyopneumoniae is the principal aetiological agent of enzootic pneumonia (EP), a chronic respiratory disease that affects mainly finishing pigs. Although major efforts to control M. hyopneumoniae infection and its detrimental effects have been made, significant economic losses in pig production worldwide due to EP continue. M. hyopneumoniae is typically introduced into pig herds by the purchase of subclinically infected animals or, less frequently, through airborne transmission over short distances. Once in the herd, M. hyopneumoniae may be transmitted by direct contact from infected sows to their offspring or between pen mates. The 'gold standard' technique used to diagnose M. hyopneumoniae infection, bacteriological culture, is laborious and is seldom used routinely. Enzyme-linked immunosorbent assay and polymerase chain reaction detection methods, in addition to post-mortem inspection in the form of abattoir surveillance or field necropsy, are the techniques most frequently used to investigate the potential involvement of M. hyopneumoniae in porcine respiratory disease. Such techniques have been used to monitor the incidence of M. hyopneumoniae infection in herds both clinically and subclinically affected by EP, in vaccinated and non-vaccinated herds and under different production and management conditions. Differences in the clinical course of EP at farm level and in the efficacy of M. hyopneumoniae vaccination suggest that the transmission and virulence characteristics of different field isolates of M. hyopneumoniae may vary. This paper reviews the current state of knowledge of the epidemiology of M. hyopneumoniae infection including its transmission, infection and seroconversion dynamics and also compares the various epidemiological tools used to monitor EP.
  The Veterinary Journal 05/2008; 181(3):221-31. · 2.24 Impact Factor
• Article: Passive transfer of maternal Mycoplasma hyopneumoniae-specific cellular immunity to piglets.

  Meggan Bandrick, Maria Pieters, Carlos Pijoan, Thomas W Molitor
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  ABSTRACT: Immunity in the neonatal animal is primarily maternally derived, either by lymphocytes that pass into the newborn across the placenta or following colostrum ingestion. However, the effect of this passively transferred cellular maternal immunity on the newborn's immune repertoire is not clearly understood. Various studies have shown that colostral lymphocytes are activated and possess functional abilities; however, no studies have shown the transfer of colostral antigen-specific T-cell-specific responses in a newborn. In this study we examined the transfer of vaccine-induced Mycoplasma hyopneumoniae cellular immunity from immune dams to newborn piglets. Newborn piglets from vaccinated and nonvaccinated dams were assessed in two ways for cellular immune responses specific to M. hyopneumoniae: (i) delayed-type hypersensitivity (DTH) testing and (ii) in vitro lymphocyte proliferation, assayed on piglet blood lymphocytes and sow colostral lymphocytes. DTH responses to M. hyopneumoniae were detected only for offspring of vaccinated sows, whereas DTH responses to the nonspecific mitogen phytohemagglutinin were seen for all piglets. M. hyopneumoniae-specific proliferation was seen for colostral lymphocytes from vaccinated sows and for blood lymphocytes from neonatal piglets of vaccinated dams but not for blood lymphocytes from piglets of nonvaccinated sows. Functional antigen-specific T cells were transferred to offspring from vaccinated sows and participated in the neonatal immune response upon stimulation. These data have implications for defining disease intervention strategies.
  Clinical and vaccine immunology: CVI 04/2008; 15(3):540-3. · 2.37 Impact Factor