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A review of porcine tonsils in immunity and disease

  • Dennis C. Horter (a1), Kyoung-Jin Yoon (a1) and Jeffrey J. Zimmerman (a1)

The porcine tonsils are a group of lymphoepithelial tissues located at the common openings of the gastrointestinal and respiratory tracts. The tonsils participate in a variety of functions involving innate, cellular and humoral immunity at the local and systemic levels. Among these immunological functions is the continuous surveillance for the presence of foreign antigens at the openings of the gastrointestinal and respiratory tracts. Within the pig, the movement of lymphocytes, cytokines and chemotactic molecules from the tonsils to other lymphoid organs confers immunity to other portals of pathogen entry and facilitates an efficient and rapid systemic immune response. In spite of the immunological nature of the tonsils, some microorganisms have acquired adaptations that allow them to circumvent the tonsillar immune defenses and utilize the tonsils as a site of entry, replication and colonization. Several bacterial and viral pathogens persist asymptomatically within the tonsils, making identification of asymptomatic carrier animals difficult in disease control and/or pathogen elimination. This paper reviews the current information on the anatomy, immunology and pathobiology of porcine tonsils and discusses the tonsils as a site of pathogen entry, replication and colonization using Salmonella spp., classical swine fever virus and porcine reproductive and respiratory syndrome virus as examples.

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Ackermann MR, De Bey MC, Register KB, Larson DJ and Kinyon JM (1994). Tonsil and turbinate colonization by toxigenic and non-toxigenic strains of Pasteurella multocida in conventionally raised Iowa swine. Proceedings of the International Pig Veterinary Society 13: 162.
Albina E, Madec F, Cariolet R and Torrison J (1994). Immune response and persistence of the porcine reproductive and respiratory syndrome virus in infected pigs and farm units. Veterinary Record 134: 567573.
Alexandersen S, Oleksiewicz MB and Donaldson AI (2001). The early pathogenesis of foot-and-mouth disease in pigs infected by contact: a quantitative time-course study using TaqMan RT–PCR. Journal of General Virology 82: 747755.
Allende R, Laegreid WW, Kutish GF, Galeota JA, Wills RW and Osorio FA (2000). Porcine reproductive and respiratory syndrome virus: description of persistence in individual pigs upon experimental infection. Journal of Virology 74: 1083410837.
Andries K and Pensaert M (1980). Immunofluorescence studies on the pathogenesis of hemagglutinating encephalomyelitis virus after oronasal inoculation. American Journal of Veterinary Research 41: 13721378.
Baekbo P (1988). Pathogenic properties of Pasteurella multocida in the lung of pigs. Proceedings of the International Pig Veterinary Society 10: 58.
Baele M, Chiers K, Devriese LA, Smith HE, Wisselink HJ, Vaneechoutte M and Haesebrouck F (2001). The gram-positive tonsillar and nasal flora of piglets before and after weaning. Journal of Applied Microbiology 91: 9971003.
Bagby GC Jr, Rigas VD, Bennett RM, Vandenbark AA and Garewal HS (1981). Interaction of lactoferrin, monocytes, and T lymphocyte subsets in the regulation of steady-state granulopoiesis in vitro. Journal of Clinical Investigation 68: 5663.
Baskerville A and Dow C (1973). Pathology of experimental pneumonia in pigs produced by Salmonella choleraesuis. Journal of Comparative Pathology 83: 207215.
Bautista EM and Molitor TW (1997). Cell-mediated immunity to porcine reproductive and respiratory syndrome virus in swine. Viral Immunology 10: 8394.
Belz GT (1998). Intercellular and lymphatic pathways associated with tonsils of the soft palate in young pigs. Anatomy and Embryology 197: 331340.
Belz GT and Heath TJ (1995). Lymphatic drainage from the tonsil of the soft palate in pigs. Journal of Anatomy 187: 491495.
Belz GT and Heath TJ (1996). Tonsils of the soft palate of young pigs: crypt structure and lymphoepithelium. Anatomical Record 245: 102113.
Bennell MA and Husband AJ (1981). Route of lymphocyte migration in pigs. I. Lymphocyte circulation in gut-associated lymphoid tissue. Immunology 42: 469474.
Beyer J, Fichtner D, Schirrmeier H, Polster U, Weiland E and Wege H (2000). Porcine reproductive and respiratory syndrome virus (PRRSV): kinetics of infection in lymphatic organs and lung. Journal of Veterinary Medicine B, Infectious Diseases And Veterinary Public Health 47: 925.
Bianchi AT, Zwart RJ, Jeurissen SH and Moonen-Leusen HW (1992). Development of the B- and T-cell compartments in porcine lymphoid organs from birth to adult life: an immunohistological approach. Veterinary Immunology and Immunopathology 33: 201221.
Binns RM and Hall JG (1966). The paucity of lymphocytes in the lymph of unanaesthetized pigs. British Journal of Experimental Pathology 47: 275280.
Binns RM and Pabst R (1988). Lymphoid cell migration and homing in the young pig: alternative immune mechanisms in action. In: Husband A (editor). Migration and Homing of Lymphoid Cells. Boca Raton: CRC Press, pp. 137174.
Boeker M, Pabst R and Rothkotter J (1999). Quantification of B, T and null lymphocyte subpopulations in the blood and lymphoid organs of the pig. Immunobiology 201: 7487.
Borror DJ (1971). Dictionary of Word Roots and Combining Forms. Palo Alto (CA): Mayfield Publishing Company.
Brandtzaeg P, Baekkefold ES, Farstad IN, Jahnsen FL, Johanson FE, Nilsen EM and Yamanaka T (1999). Regional specialization in the mucosal immune system: what happens in the microcompartments? Immunology Today 20: 141151.
Brown TT Jr, Shin KO and Fuller FJ (1995). Detection of pseudorabies viral DNA in tonsillar epithelial cells of latently infected pigs. American Journal of Veterinary Research 56: 587594.
CDC (2001). Preliminary FoodNet data on the incidence of foodborne illnesses—selected sites, United States, 2000. Morbidity and Mortality Weekly Report 50: 241246.
Cheville NF and Mengeling WL (1969). The pathogenesis of chronic hog cholera (swine fever): histologic, immunofluorescent, and electron microscopic studies. Laboratory Investigations 20: 261274.
Choi C and Chae C (2003). Detection of classical swine fever virus in boar semen by reverse transcription–polymerase chain reaction. Journal of Veterinary Diagnostic Investigations 15: 3541.
Colgrove G, Haelterman EO and Coggins L (1969). Pathogenesis of African swine fever virus in young pigs. American Journal of Veterinary Research 30: 13431359.
Cooper NR (1985). The classical complement pathway. Activation and regulation of the first complement component. Advances in Immunology 37: 151216.
Darwich L, Segales J, Domingo M and Mateu E (2002). Changes in CD4(+), CD8(+), CD4(+), CD8(+), and immunoglobulin M-positive peripheral blood mononuclear cells of postweaning multisystemic wasting syndrome-affected pigs and age-matched uninfected wasted and healthy pigs correlate with lesions and porcine circovirus type 2 load in lymphoid tissues. Clinical and Diagnostic Laboratory Immunology 9: 236–42.
Davies PR and Ossowicz CJ (1991). Evaluation of methods used for detecting Streptococcus suis type 2 in tonsils, and investigation of the carrier state in pigs. Research in Veterinary Science 50: 190194.
de Jong MF, Wellenberg G, Schaake J and Frik K (1988). Selection of pig breeding herds free from atrophic rhinitis by means of a bacteriological screening of pigs on DNT producing Pasteurella multocida: a field evaluation from 1981 until 1987. Proceedings of the International Pig Veterinary Society 10: 49.
Dekker A, Moonen P, de Boer-Luijtze EA and Terpstra C (1995). Pathogenesis of swine vesicular disease after exposure of pigs to an infected environment. Veterinary Microbiology 45: 243–50.
Devriese LA, Hommez J, Pot B and Haesebrouck F (1994). Identification and composition of the streptococcal and enterococcal flora of tonsils, intestines and faeces of pigs. Journal of Applied Bacteriology 77: 3136.
Dick CP, Johnson RP and Yamashiro S (1989). Sites of persistence of feline calicivirus. Research in Veterinary Science 47: 367–73.
Dillender MJ and Lunney JK (1993). Characteristics of T lymphocyte cell lines established from NIH minipigs challenge inoculated with Trichinella spiralis. Veterinary Immunology and Immunopathology 35: 301319.
Dunne HW (1973). Hog cholera (European swine fever). Advances in Veterinary Science and Comparative Medicine 17: 315359.
Edwards S, Fukusho A, Lefevre P-C, Lipowski A, Pejsak Z, Roehe P and Westergaard J (2000). Classical swine fever: The global situation. Veterinary Microbiology 73: 103119.
Ellis J, Hassard L, Clark E, Harding J, Allan G, Willson P, Strokappe J, Martin K, McNeilly F, Meehan B, Todd D and Haines D (1998). Isolation of circovirus from lesions of pigs with postweaning multisystemic wasting syndrome. Canadian Veterinary Journal 39: 4451.
Elvinger F, Liggett AD, Tang KN, Harrison LR, Cole JR Jr, Baldwin CA and Nessmith WB (1994). Eastern equine encephalomyelitis virus infection in swine. Journal of the American Veterinary Medical Association 205: 10141016.
Fedorka-Cray PJ, Whipp SC, Isaacson RE, Nord N and Lager K (1994). Transmission of Salmonella typhimurium to swine. Veterinary Microbiology 41: 333344.
Fedorka-Cray PJ, Kelley LC, Stabel TJ, Gray JT and Laufer JA (1995). Alternate routes of invasion may affect pathogenesis of Salmonella typhimurium. Infection and Immunity 63: 26582664.
Fleming A (1922). On a remarkable bacteriolytic element found in tissues and secretions. Proceedings of the Royal Society of London Series B 93: 306317.
Fu Y and Galan JE (1999). A Salmonella protein antagonizes Rac-1 and Cdc42 to mediate host-cell recovery after bacterial invasion. Nature 401: 293297.
Gram T, Ahrens P and Nielsen JP (1996). Evaluation of a PCR for detection of Actinobacillus pleuropneumoniae in mixed bacterial cultures from tonsils. Veterinary Microbiology 51: 95104.
Gray JT, Fedorka-Cray PJ, Stabel TJ and Ackermann MR (1995). Influence of inoculation route on the carrier state of Salmonella choleraesuis in swine. Veterinary Microbiology 47: 4359.
Hancock RE and Scott MG (2000). The role of antimicrobial peptides in animal defenses. Proceedings of the National Academy of Sciences of the United States of America 97: 88568861.
Hardy GA, Imami N and Gotch FM (2002). Improving HIV-specific immune responses in HIV-infected patients. Journal of HIV Therapy 7: 4045.
Harms PA, Sorden SD, Halbur PG, Bolin SR, Lager KM, Morozov I and Paul PS (2001). Experimental reproduction of severe disease in CD/CD pigs concurrently infected with type 2 porcine circovirus and porcine reproductive and respiratory syndrome virus. Veterinary Pathology 38: 528539.
Higgins R and Gottschalk M (1999). Streptococcal diseases. In: Straw BE, D'Allaire S, Mengeling WL and Taylor DJ (editors). Diseases of Swine. 8th edn. Ames (IA): Iowa State Press pp. 563578.
Horter DC, Pogranichniy RM, Chang CC, Evans RB, Yoon KJ and Zimmerman JJ (2002). Characterization of the carrier state in porcine reproductive and respiratory syndrome virus infection. Veterinary Microbiology 86: 213–28.
Howerth EW, Stallknecht DE, Dorminy M, Pisell T and Clarke GR (1997). Experimental vesicular stomatitis in swine: effects of route of inoculation and steroid treatment. Journal of Veterinary Diagnostic Investigations 9: 136142.
Howie AJ (1981). The cells in tonsillar crypts. Clinical Otolaryngology and Allied Sciences 7: 3544.
Kassay D and Sandor A (1962). The crypt system of the palatine tonsils. Archives of Otolaryngology 75: 144155.
Kleiboeker SB, Lehman JR and Fangman TJ (2002). Concurrent use of reverse transcription–polymerase chain reaction testing of oropharyngeal scrapings and paired serological testing for detection of porcine reproductive and respiratory syndrome virus infection in sows. Journal of Swine Health and Production 10: 251258.
Kotenko SV, Saccani S, Izotova LS, Mirochnitchenko OV and Pestka S (2000). Human cytomegalovirus harbors its own unique IL-10 homologue (cmvIL-10). Proceedings of the National Academy of Sciences of the United States of America 97: 16951700.
Krmpoti A, Busch DH, Bubi I, Gebhardt F, Hengel H, Hasan M, Scalzo AA, Koszinowski UH and Jonji S (2002). MCMV glycoprotein gp40 confers virus resistance to CD8+ T cells and NK cells in vivo. Nature Immunology 3: 529535.
Kume K, Nakai T and Sawata A (1984). Isolation of Haemophilus pleuropneumoniae from the nasal cavities of healthy pigs. Japanese Journal of Veterinary Science 46: 641647.
Kwapinski JBG (1972). Methodology of Immunochemical and Immunological Research. New York: John Wiley and Sons pp. 609611.
Laufer J, Oren R, Goldberg I, Horwitz A, Kopolovic J, Chowers Y and Passwell JH (2000). Cellular localization of complement C3 and C4 transcripts in intestinal specimens from patients with Crohn's disease. Clinical Experimental Immunology 120: 3037.
Levitskaya J, Coram M, Levitsky V, Imreh S, Steigerwald-Mullen PM, Klein G, Kurilla MG and Masucci MG (1995). Inhibition of antigen processing by the internal repeat region of the Epstein–Barr virus nuclear antigen 1. Nature 375: 685688.
Levitskaya J, Sharipo A, Leonchiks A, Ciechanover A and Masucci MG (1997). Inhibition of ubiquitin/proteasome-dependent protein degradation by the Gly-Ala repeat domain of the Epstein–Barr virus nuclear antigen 1. Proceedings of the National Academy of Sciences of the United States of America 94: 1261612621.
Loemba HD, Mounir S, Mardassi H, Archambault D and Dea S (1996). Kinetics of humoral immune response to the major structural proteins of the porcine reproductive and respiratory syndrome virus. Archives of Virology 141: 751761.
Long JF (1985). Pathogenesis of porcine polioencephalomyelitis. In: Olsen RA, Krakowka S and Blakeslee JR (editors). Comparative Pathobiology of Viral Diseases, Vol. 1. Boca Raton (FL): CRC Press pp. 179197.
Madsen LW, Svensmark B, Elvestad K, Aalbaek B and Jensen HE (2002). Streptococcus suis serotype 2 infection in pigs: new diagnostic and pathogenetic aspects. Journal of Comparative Pathology 126: 5765.
McClurkin AW, Littledike ET, Cutlip RC, Frank GH, Coria MF and Bolin SR (1984). Production of cattle immunotolerant to bovine viral diarrhea virus. Canadian Journal of Comparative Medicine 48: 156161.
Meyerholz DK, Stabel TJ, Ackermann MR, Carlson SA, Jones BD and Pohlenz J (2002). Early epithelial invasion by Salmonella enterica serovar Typhimurium DT104 in the swine ileum. Veterinary Pathology 39: 712720.
Morozov I, Sirinarumitr T, Sorden SD, Halbur PG, Morgan MK, Yoon KJ and Paul PS (1998). Detection of a novel strain of porcine circovirus in pigs with postweaning multisystemic wasting syndrome. Journal of Clinical Microbiology 36: 25352541.
Murakami S, Azuma R, Koeda T, Oomi H, Watanabe T and Fujiwara H (1998). Immunohistochemical detection for Actinomyces sp. in swine tonsillar abscess and granulomatous mastitis. Mycopathologia 141: 15–9.
Neutra MR, Pringault E and Kraehenbuhl JP (1996). Antigen sampling across epithelial barriers and induction of mucosal immune responses. Annual Review of Immunology 14: 275300.
Nielsen B, Heisel C and Wingstrand A (1996). Time course of the serological response to Yersinia enterocolitica O:3 in experimentally infected pigs. Veterinary Microbiology 48: 293303.
Pabst R and Binns RM (1989). Heterogeneity of lymphocyte homing physiology: several mechanisms operate in the control of migration to lymphoid and non-lymphoid organs in vivo. Immunology Reviews 108: 83109.
Pabst R and Nowara E (1984). The emigration of lymphocytes from palatine tonsils after local labeling. Archives of Otorhinolaryngology 240: 713.
Pantaleo G, Graziosi C, Butini L, Pizzo PA, Schnittman SM, Kotler DP and Fauci AS (1991). Lymphoid organs function as major reservoirs for human immunodeficiency virus. Proceedings of the National Academy of Sciences of the United States of America 88: 98389842.
Paton D (2002). The reappearance of classical swine fever in England in 2000. In: Morilla A, Yoon K-J and Zimmerman JJ (editors). Trends in Emerging Viral Infections of Swine. Ames (IA): Iowa State Press pp. 153158.
Payne JM and Derbyshire JB (1963). Portals of entry for bacterial infection in calves and piglets with particular reference to the tonsil. Journal of Pathology and Bacteriology 85: 171178.
Payne S, Parekh B, Montelaro RC and Issel CJ (1984). Genomic alterations associated with persistent infections by equine infectious anaemia virus, a retrovirus. Journal of General Virology 65: 13951399.
Perry ME (1994). The specialized structure of crypt epithelium in the human palatine tonsil and its functional significance. Journal of Anatomy 185: 111127.
Pescovitz MD, Sakopoulos AG, Gaddy JA, Husmann RJ and Zuckermann FA (1994). Porcine peripheral blood CD4+/CD8+ dual expressing T-cells. Veterinary Immunology and Immunopathology 43: 53.
Ploegh HL (1998). Viral strategies of immune evasion. Science 280: 248–53.
Pospischil A, Wood RL and Anderson TD (1990). Peroxidase-antiperoxidase and immunogold labeling of Salmonella typhimurium and Salmonella choleraesuis var kunzendorf in tissues of experimentally infected swine. American Journal of Veterinary Research 51: 619624.
Rabsch W, Tschape H and Baumler AJ (2001). Non-typhoidal salmonellosis: emerging problems. Microbes and Infection 3: 237247.
Ramos JA, Ramis AJ, Rabanal RM, Marco A, Domingo M and Ferrer LM (1990). Scanning electron microscopy of swine lymphoid organs. Histology and Histopathology 5: 397406.
Ramos JA, Ramis AJ, Marco A, Domingo M, Rabanal R and Ferrer L (1992). Histochemical and immunohistochemical study of the mucosal lymphoid system in swine. American Journal of Veterinary Research 53: 14181426.
Ressang AA (1973). Studies on the pathogenesis of hog cholera. I. Demonstration of hog cholera virus subsequent to oral exposure. Zentralblatt für Veterinärmedizin 20: 256271.
Robertson A, Bannister GL, Boulanger P, Appel M and Gray DP (1965). Hog cholera. V. Demonstration of the antigen in swine tissues by the fluorescent antibody technique. Canadian Journal of Comparative Medicine and Veterinary Science 29: 299305.
Rossow KD, Benfield DA, Goyal SM, Nelson EA, Christopher-Hennings J and Collins JE (1996). Chronological immunohistochemical detection and localization of porcine reproductive and respiratory syndrome virus in gnotobiotic pigs. Veterinary Pathology 33: 551556.
Rutter JM (1985). Atrophic rhinitis in swine. Advances in Veterinary Science and Comparative Medicine 29: 239279.
Saalmuller A, Redehasse MJ, Buhring HJ, Jonjic S and Koszinowski UH (1987). Simultaneous expression of CD4 and CD8 antigens by a substantial proportion of resting porcine T lymphocytes. European Journal of Immunology 17: 1297.
Saar LI and Getty R (1964). The interrelationship of the lymph vessel connections of the lymph nodes of the head, neck, and shoulder regions of swine. American Journal of Veterinary Research 25: 618636.
Sahasrabudhe KS, Kimball JR, Morton TH, Weinberg A and Dale BA (2000). Expression of the antimicrobial peptide, human beta-defensin 1, in duct cells of minor salivary glands and detection in saliva. Journal of Dental Research 79: 16691677.
Salles MW and Middleton DM (2000). Lymphocyte subsets in porcine tonsillar crypt epithelium. Veterinary Immunology and Immunopathology 77: 133144.
Salles MW, Perez-Casal J, Willson P and Middleton DM (2002). Changes in the leucocyte subpopulations of the palatine tonsillar crypt epithelium of pigs in response to Streptococcus suis type 2 infection. Veterinary Immunology and Immunopathology 87: 5163.
Sallusto F, Lanzavecchia A and Mackay CR (1998). Chemokines and chemokine receptors in T-cell priming and Th1/Th2-mediated responses. Immunology Today 19: 568574.
Salmon DE (1889). Hog cholera: its history, nature, and treatment. Washington: Bureau of Animal Industry, US Department of Agriculture, Washington Printing Office, p. 32.
Sato Y, Wake K and Watanabe I (1990). Differentiation of crypt epithelium in human palatine tonsils: the microenvironment of crypt epithelium as a lymphoepithelial organ. Archives of Histology and Cytology 53: 4154.
Schummer A and Nickel R (1979). Digestive system. In: Sack WO (editor). The Viscera of the Domestic Mammals, 2nd edn. Berlin: Springer-Verlag pp. 5155.
Senkevich TG, Bugert JJ, Sisler JR, Koonin EV, Darai G and Moss B (1996). Genome sequence of a human tumorigenic poxvirus: prediction of specific host-response-evasion genes. Science 273: 813816.
Shadduck JA, Koestner A and Kasza L (1967). The lesions of porcine adenoviral infection in germfree and pathogen-free pigs. Pathologia Veterinaria 4: 537552.
Sharipo A, Imreh M, Leonchiks A, Brändén C-I and Masucci MG (2001). cis-Inhibition of proteasomal degradation by viral repeats: impact of length and amino acid composition. FEBS Letters 499: 137142.
Shi J, Zhang G, Wu H, Ross C, Blecha F and Ganz T (1999). Porcine epithelial beta-defensin 1 is expressed in the dorsal tongue at antimicrobial concentrations. Infection and Immunity 67: 31213127.
Slipka J (1988). Palatine tonsils—their evolution and ontogeny. Acta Oto-laryngologica 454: 1822.
Solorzano RF, Thigpen JE, Bedell DM and Schwartz WL (1966). The diagnosis of hog cholera by a fluorescent antibody test. Journal of the American Veterinary Medical Association 149: 3134.
Stephano AH, Gay GM and Ramirez TC (1988). Encephalomyelitis, reproductive failure and corneal opacity in pigs, associated with a new paramyxovirus infection (blue eye). Veterinary Record 122: 610.
Terpstra C and Wensvoort G (1988). Bovine viral diarrhea virus infections in piglets born to sows vaccinated against swine fever with contaminated vaccine. Research in Veterinary Science 45: 143148.
Terpstra C and de Smit AJ (2000). The 1997/1998 epizootic of swine fever in the Netherlands: control strategies under a non-vaccination regimen. Veterinary Microbiology 77: 315.
Terpstra C, Wensvoort G and Pol JMA (1991). Experimental reproduction of porcine epidemic abortion and respiratory syndrome (mystery swine disease) by infection with Lelystad virus: Koch's postulates fulfilled. Veterinary Quarterly 13: 131136.
Terzic S, Sver L, Valpotic I, Lojkic M, Miletic Z, Jemersic L, Lackovic G, Kovsca-Janjatovic A and Orsolic N (2002). Immunophenotyping of leukocyte subsets in peripheral blood and palatine tonsils of prefattening pigs. Veterinary Research Communications 26: 273283.
Thibodeau V, Frost EH, Chenier S and Quessy S (1999). Presence of Yersinia enterocolitica in tissues of orally-inoculated pigs and the tonsils and feces of pigs at slaughter. Canadian Journal of Veterinary Research 63: 96100.
Trautmann A and Fiebiger J (1957). Fundamentals of the Histology of Domestic Animals. Ithaca (NY): Comstock Publishing Associates pp. 121123.
Uchiya K, Barbieri MA, Funato K, Shah AH, Stahl PD and Groisman EA (1999). A Salmonella virulence protein that inhibits cellular trafficking. EMBO Journal 18: 39243933.
Van Oirschot JT and Terpstra C (1977). A congenital persistent swine fever infection. I. Clinical and virological observations. Veterinary Microbiology 2: 121132.
Velinova M, Thielen C, Melot F, Donga J, Eicher S, Heinen E and Antoine N (2001). New histochemical and ultrastructural observations on normal bovine tonsils. Veterinary Record 149: 613617.
Wensvoort G, Terpstra C, Pol JM, ter Laak EA, Bloemraad M, de Kluyver EP, Kragten C, van Buiten L, den Besten A and Wagenaar F (1991). Mystery swine disease in the Netherlands: the isolation of Lelystad virus. Veterinary Quarterly 13: 121130.
Wheeler JG and Osorio FA (1991). Investigation of sites of pseudorabies virus latency, using polymerase chain reaction. American Journal of Veterinary Research 52: 17991803.
Wilcock BP and Olander HJ (1978). Influence of oral antibiotic feeding on the duration and severity of clinical disease, growth performance and pattern of shedding in swine inoculated with Salmonella typhimurium. Journal of the American Veterinary Medical Association 172: 472477.
Wilcock BP, Armstrong CH and Olander HJ (1976). The significance of the serotype in the clinical and pathologic features of naturally occurring porcine salmonellosis. Canadian Journal of Comparative Medicine 40: 8088.
Williams DM and Rowland AC (1972). The palatine tonsils of the pig—an efferent route to the lymphoid tissue. Journal of Anatomy 113: 131137.
Williams DM, Lawson GHK and Rowland AC (1973). Streptococcal infection in piglets: the palatine tonsil as portals of entry for Streptococcus suis. Research in Veterinary Science 15: 352362.
Wills RW, Zimmerman JJ, Yoon KJ, Swenson SL, McGinley MJ, Hill HT, Platt KB, Christopher-Hennings J and Nelson EA (1997). Porcine reproductive and respiratory syndrome virus: a persistent infection. Veterinary Microbiology 55: 231240.
Winkler MT, Doster A and Jones C (2000). Persistence and reactivation of bovine herpesvirus 1 in the tonsils of latently infected calves. Journal of Virology 74: 53375346.
Wood RL and Rose R (1992). Populations of Salmonella typhimurium in internal organs of experimentally infected carrier swine. American Journal of Veterinary Research 53: 653658.
Wood RL, Pospischil A and Rose R (1989). Distribution of persistent Salmonella typhimurium infection in internal organs of swine. American Journal of Veterinary Research 50: 10151021.
Wu AM, Csako G and Herp A (1994). Structure, biosynthesis, and function of salivary mucins. Molecular and Cellular Biochemistry 17: 3955.
Yamamoto Y, Okato S, Nishiyama M and Takahashi H (1992). Function and morphology of macrophages in palatine tonsils. Advances in Otorhinolaryngology 47: 107113.
Zhang G, Ross CR and Blecha F (2000). Porcine antimicrobial peptides: new prospects for ancient molecules of host defense. Veterinary Research 31: 277296.
Zimmerman JJ (2003). Historical overview. In: Zimmerman JJ and Yoon K-J (editors). The Porcine Reproductive and Respiratory Syndrome (Porcine Arterivirus) Compendium 2nd edn. Des Moines (IA): National Pork Board pp. 16.
Zimmerman JJ, Sanderson T, Eernisse KA, Hill HT and Frey ML (1992). Transmission of SIRS virus in convalescent animals to commingled penmates under experimental conditions. American Association Swine Practitioners Newsletter 4: 25.
Zuckermann FA (1999). Extrathymic CD4/CD8 double positive T cells. Veterinary Immunology and Immunopathology 72: 5566.
Zuckermann FA and Gaskins HR (1996). Distribution of porcine CD4/CD8 double-positive T lymphocytes in mucosa-associated lymphoid tissues. Immunology 87: 493499.
Zuckermann FA and Husmann RJ (1996). Functional and phenotypic analysis of porcine peripheral blood CD4/CD8 double-positive T cells. Immunology 87: 500512.
Zwirner J, Felber E, Schmidt P, Riethmuller G and Feucht HE (1989). Complement activation in human lymphoid germinal centres. Immunology 66: 270277.
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