Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Orthohantavirus wikipedia , lookup
Foot-and-mouth disease wikipedia , lookup
Hepatitis B wikipedia , lookup
Marburg virus disease wikipedia , lookup
Henipavirus wikipedia , lookup
Canine distemper wikipedia , lookup
Taura syndrome wikipedia , lookup
Avian influenza wikipedia , lookup
Canine parvovirus wikipedia , lookup
Bull. Vet. Inst. Pulawy 46, 45-52, 2002 ANTIGENIC CHARACTERIZATION OF POLISH INFECTIOUS BURSAL DISEASE VIRUS STRAINS KATARZYNA DOMAŃSKA, GAËLLE RIVALLAN*, KRZYSZTOF ŚMIETANKA, DIDIER TOQUIN*, ZENON MINTA, AND NICOLAS ETERRADOSSI* Department of Poultry Diseases, National Veterinary Research Institute, 24-100 Pulawy, Poland *Laboratoire d’Etudes et de Recherches Avicoles et Porcines – Unité de Virologie Immunologie et Parasitologie Aviaires et Cunicoles, Agence Française de Securité Sanitaire des Aliments (AFSSA), BP 53-22440 Ploufragan, France Antigen Capture-ELISA based on eight different neutralizing mouse monoclonal antibodies (Mabs) was used to study Polish infectious bursal disease viruses (IBDVs) isolated from two epidemics on the turn of 70/80s (early IBDV) and in the 90s (recent IBDV). They were compared to the Faragher 52/70 (F52/70) reference strain of European classical serotype 1 IBDV and to the 89/163 (typical) and 91/168 (atypical) French very virulent (vv) IBDV isolates. All Polish viruses, irrespective of the isolation date, exhibited antigenic profile which was different from the F52/70 reference strain (no binding of Mabs 3 and 4). Two of the early IBDVs did not react with Mab 5 and two of six recent IBDV did not react with Mab 8. The other recent Polish viruses had an antigenic reactivity similar to that of typical vvIBDV. Key words: infectious bursal disease virus, IBDV, Antigen Capture–ELISA, monoclonal antibody. Infectious bursal disease (IBD) is an important virus-induced, highly contagious disease of chickens (31). The disease causes heavy economical losses due to immunosuppression in subclinical cases or to acute cases associated with mortality, haemorrhages and bursal damage. Since the first report in the USA (3) the disease became widespread all over the world. In Europe it appeared for the first time in the middle of 1960s. Until 1987 the strains of the virus were of low virulence, they caused low mortality, and were satisfactorily controlled by vaccination. However, in 1987 some vaccination failures were described in different parts of the world (2, 10, 24, 28). In the USA, it was demonstrated that the new isolates had been affected by an antigenic drift against which classical IBD virus (IBDV) vaccines were not satisfactorily protective (11, 27). In Europe, the first cases of acute IBDV were described at the same time (2, 28). The acute forms of the disease, caused by very virulent strains, were then described in Japan in the early 1990s (12, 23) and they have rapidly spread all over the world (30). During the 63rd General Session of the Office International des Epizooties (OIE, Paris, 15-19 May 1995), it was estimated that IBD has a considerable socio- 46 economic importance at the international level, as the disease is present in more than 95% of Member Countries (6). IBDV is a small, non-enveloped virus belonging to the family Birnaviridae. The genomes of the virus consist of two segments of double-stranded RNA contained within a single-shelled icosahedral capsid composed of four structural proteins (4). Two of these proteins, VP2 and VP3, are major immunogens. VP2 (MW 40-45 kDa) encoded by the larger genome segment, has major neutralizing, conformational epitopes within a central variable region. This part is named “VP2 variable domain” because most of the amino acids (aa) changes between antigenically different IBDVs are clustered in this area. Major differences in the reactivity of IBDV strains with neutralizing Mabs may be referred to aa changes in two hydrophilic aa sets termed peak A and B which flank VP2 variable domain (25, 29). Antigenic diversity among IBDV isolates has been recognized since 1981 when serotypes 1 and 2 were defined on the basis of their lack of in vitro crossneutralization (15). So far, virus strains that are pathogenic for chicken have all been shown to belong to serotype 1. Further antigenic differences have been demonstrated within this serotype since 1984, and the study of North-American IBDV isolates causing little mortality but significant immunosuppression has led to dividing the serotype into six subtypes which were originally differentiated by cross-neutralization assays using polyclonal sera (11). Studies based on Mabs subsequently demonstrated a growing number of modified neutralizing epitopes in the recent serotype 1 isolates from the United States, which were designated as “variant viruses”. It was hence suggested that North-American IBDV isolates might have been affected by an antigenic drift and the epidemiology of IBDV in the US has been defined since then by the natural occurrence of neutralizing monoclonal antibodies escape variants (26, 27). In Poland first cases of IBD were diagnosed at the end of 60s but the real epidemic of IBD occurred at the end of 70s (1, 14, 16). Despite of a wide spreading of IBDV, the clinical form of the disease was rarely observed. The field strains isolated in 1978 and 1980 revealed low pathogenicity for SPF chickens (17, 18). However, they caused economic losses due to impaired growth and acquired immunodeficiency (19). At the end of 1991 the first cases of acute form of IBD were diagnosed in western and central Poland. During the next year the disease spread rapidly throughout the whole country and affected broilers and laying pullets flocks with mortality up to 50% and 70%, respectively (20, 21). Pathotypic characterization of the IBDVs isolated in 1991-93 confirmed their high virulence (22). Mortality rates in challenged 4-weekold SPF chickens ranged from 40 to 100%. The aim of the present study was to compare antigenically early and recent Polish IBDV isolates in a Mab-based Antigen Capture-ELISA (AC-ELISA). Materials and Methods Viruses. Three early Polish isolates 78/GSi, 78/GSz and 80/GA were collected during the first epidemic of IBDV in Poland between 1978-80. Six recent IBDV strains were isolated in 1990-2000 from chickens with clinical symptoms of acute form of IBDV. The reference IBDV strains included in this study were the Faragher 52/70 (F52/70) strain as reference for the classical European serotype 1 strains, the French 89/163 strain as reference for the very virulent (vv) IBDV and the 91168 strain as an atypical vvIBDV (7). The viruses (isolates and strains) were propagated in 4-to-6- 47 week-old SPF chickens, with sampling of the infected bursae 4 days p.i. Bursal homogenates were prepared by blending the bursae w/v in phosphate buffered saline (PBS), then clarified v/v in Freon. All viruses were stored at -70 0C. AC-ELISA. The antigenic characterization was performed using a Mab based AC-ELISA according to Eterradossi (7). The study was performed in two steps, the first aimed at standardizing the amount of captured antigens (with polyclonal ascitic fluid), the second one at measuring Mab binding in a Mab-based AC-ELISA (7). Briefly, 96-well polystyrene plates were coated with a chicken anti-F52/70 polyclonal antiserum, diluted in PBS. Blocking was then achieved by incubating the coated plates overnight at 370C with a blotto-tween solution containing 10% foetal calf serum and 0.02% sodium azide. Bursal homogenates were then incubated with the coated plates for 1 h at 370C. After incubation the captured IBDV antigens were detected with mouse polyclonal anti-IBDV antibodies or with a panel of eight mouse anti-IBDV neutralizing Mabs 1, 3, 4, 5, 6, 7, 8 and 9 (ascitic fluids) followed by a goat anti-mouse alkalinephosphatase conjugate (KPL, USA), both incubated for 1 h at 370C. Optical densities (OD) were read at 405 nm after incubating an alkaline-phosphatase substrate (pNPP, Sigma, USA) for 1 h at 370C. All immunological reagents used in each step of the assay were first equilibrated so that the capture of an undiluted infected bursal homogenate would yield an OD averaging the maximum reading value of the reader (3.000). In the next step the equilibration of the captured antigen was assayed; dilutions yielding 50% of the maximum OD were used in the antigenic typing. These dilutions ensure that differences in the intensity of binding of Mabs originate from true antigenic differences of the tested viruses, and not from the testing of different quantities of the same virus that may be captured at various level resulting from variation of the antigenic content in bursae infected by the same virus. Additionally, a few controls were included in each assay: the evaluation of the unspecific binding of mouse antibody (an equilibrated dose of the infected homogenates with a negative mouse ascitic fluid containing no anti-IBDV Mab), the control of the 50% effect that was to be yielded by the equilibrated antigens (an equilibrated dose of both the infected and the SPF homogenates with a mouse polyclonal ascitic fluid) and the control of the maximum effect (the undiluted infected and SPF homogenates with polyclonal ascitic fluid). The reactivity of the different Mabs was calculated as a percentage, according to the formula below (4, 6, 9). Percentage of reactivity = OD Mab _ OD Negative ascitic fluid x100 OD Reference polyclonal _ OD Negative ascitic fluid Results In AC-ELISA, all bursal homogenates containing the recent Polish IBDVs proved to contain high amounts of IBDV antigens, and compared well with the reference F52/70-, 89/163- and 91/168-containing homogenates (optical densities ranging 2.2 to 2.9). On the contrary, all homogenates prepared from bursae infected with the early Polish isolates contained low amounts of antigens (optical densities ranging from 0.5 to 1.0). 48 Table 1 presents the reactivity of the eight anti-IBDV Mabs in paired ACELISAs performed with 12 viruses (the following marks are used: differences in the Mab reactivity of the tested viruses from F52/70 are evidenced as gray areas of the table, reduced binding (<25%) of the Mab with the tested viruses are evidenced as pale shading, lack of binding (<15%) as darker shading of the table). None of the tested Polish IBDV strains allowed significant binding of Mab 3 and 4 (mean reactivities of these Mabs ranging from 0-2% and 0-14%, respectively). This result suggests that the studied viruses, irrespective of their date of isolation, might have aa changes in the first major hydrophilic peak (peak A) of VP2 variable domain. This was a very interesting finding, for the early IBDV strains isolated before the emergence of the acute form of IBD all had shown a classical antigenicity (high reactivity versus all Mabs as a reference F52/70). Moreover, two early Polish viruses (78/GSi and 80/Ga) did not react with Mab 5 and also exhibited a two- to three-fold reduction in the binding of Mab 8 (mean reactivities were 31% and 21% for 78/GSi and 80/Ga, respectively, versus 2-3% in atypical vv IBDV or 82-88% in typical isolates). From previous studies, the lack of or a low reactivity with Mab 5 was considered as an indication of aa changes in the first minor hydrophilic peak of VP2 variable domain. Two of the recent Polish viruses (92/111 and 93/35) exhibited an antigenic profile similar to the atypical French 91/168 isolate as they did not react with Mab 8. This result suggested that aa changes may exist in their second major hydrophilic peak B. The 91/272, 94/48, 99/150 and 00/40 viruses had an antigenic reactivity similar to that of typical vvIBDV. Discussion Regarding recent Polish viruses, four of them had exactly the same antigenic profile as typical vvIBDVs (no binding of Mabs 3 and 4). The present study could confirm previous pathotypic studies and demonstrate that vvIBDVs are now present in Poland. Interestingly, two of the recent Polish viruses (isolates 92/11 and 93/35) appeared to be antigenically different from other vvIBDVs, as did the 91/168 French atypical vvIBDV strain, because they all had a reduced ability to bind Mab 8. As shown for the French strain 91/168 responsible for this are aa differences located at the C-terminal end of peak B (Q324L in 91/168 in comparison to other typical vvIBDV) (8). As these atypical French and Polish vvIBDV-related isolates have been isolated during a relatively short period (1991-1993) and so far have not been isolated elsewhere, it is tempting to speculate that the same IBDV strains were exchanged between the two countries. However, the epidemiological links between the outbreaks in the two countries are not known and more isolates collected in the same areas / periods would be necessary to precise where the virus was originally prevalent. A 1989-1997 survey of French vvIBDV isolates suggested that the 91/168 strain caused only a sporadic outbreak in France and did not replace in this country the more typical 89163-like vvIBDVs. 49 Table 1 Antigenic characterization of Polish IBDV strains in a Mab-based AC-ELISA IBDV strain Reactivity in AC-ELISA with Mab1 Mab3 Mab4 Mab5 Mab6 Mab7 Mab8 Mab9 72a 71 58 59 88 96 91 76 71-72 68-73 51-65 52-65 76-100 90-102 86-96 74-78 89/163 typical vvIBD V 58 50-66 1 0-1 6 3-8 27 17-37 95 101-88 86 78-94 76 60-92 73 76-69 91/168 atypica l vvIBD V 62 61-62 1 1-1 15 10-19 46 32-60 96 82-109 50 30-69 3 2-4 68 57-79 31 26-35 61 52-70 17 16-18 68 45-91 82 66-98 72 66-78 65 62-67 89 97-80 72 71-72 0 0-0 2 1-2 2 1-2 2 1-2 1 1-1 2 1-3 1 0-2 1 0-1 2 1-3 1 0-1 6 5-7 0 0-0 11 8-13 13 10-15 14 14-14 8 6-10 9 7-11 12 7-16 0 0-0 58 45-70 2 0-4 60 51-68 46 36-55 44 45-43 39 31-46 62 56-68 53 47-58 115 118 106-123 119-117 119 117 106-131 99-135 88 94 94-82 93-95 96 104 89-102 97-111 123 51 99-146 34-68 113 56 106-120 42-69 109 112 113-104 107-117 104 107 114-94 118-95 129 118 108-149 110-125 31 30-32 88 85-91 21 17-25 82 63-101 2 2-2 3 2-4 84 75-93 86 85-87 88 84-92 121 118-124 79 73-84 98 102-94 68 67-69 77 69-85 76 73-79 76 73-78 72 71-73 81 80-82 F52/70 b 78/GSi 78/GSz 80/GA 91/272 92/111 93/35 94/48 99/150 00/40 a b : Mean result from two repeated tests. : Range in two repeated tests. 50 Unexpected results were also obtained with the 78/GSz, 78/GSi and 80/GA early Polish viruses. Indeed, these isolates did not react with Mabs 3 and 4 and the two latter viruses also reacted poorly, if at all, with Mabs 5 and 8. Hence, the neutralizing epitopes present on the early Polish IBDVs were clearly different in comparison with both the European F52/70 reference strain and the recent vvIBDV isolates from Poland. With respect to strain identification in the laboratory, the results concerning early Polish viruses are interesting as several previous studies had suggested that the lack of reactivity to Mabs 3 and 4 in AC-ELISA might be a character of very virulent and variant IBDVs and help in differentiation between classical and recent isolates in addition to pathogenicity testing (9). The present results indicate that early Polish IBDVs isolated between 1978-80, hence before the identification of variant and very virulent strains, may also not react with Mab 3 and 4, in spite of being early strains with a low pathogenicity. It should be remembered that bursal homogenates contaminated with the early Polish isolates contained low amounts of IBDV antigens, as compared with homogenates containing pathogenic strains such as F52/70 or the vvIBDVs. Hence, as precised previously (6, 9), both the high antigen content in bursal homogenates and the lack of binding of Mabs 3 and 4 should be considered as relevant in the presumptive identification of vvIBDVs. The identification should always be definitively assessed by pathogenicity testing (8). With respect to IBDV epidemiology, the present results of testing early Polish isolates are also interesting. Indeed, the current idea is that early IBDVs, prevalent worldwide until the emergence of the US variants and vvIBDVs, were “classical” ones with more or less the same antigenic profile as strain F52/70. This theory stems from the antigenic and genetic study, firstly of a limited number of early pathogenic viruses which have been maintained as reference strains (e.g. the 002/73, STC, Cu1 and F52/70 strains), and secondly of some IBD attenuated vaccine strains which have been developed from several early IBDV isolates (Lukert strain, D78, etc). However, the extent to which early IBDVs were actually antigenically and genetically homogeneous is not known precisely, as the number of available early IBDV strains is, unfortunately, limited. Similarly, it is not known whether other IBDV strains, possibly involved in subclinical infections, were present in Europe before the F52/70-like viruses were isolated. These points might be important to investigate, as the epidemiological origin of the IBDV strains that have recently emerged in Europe is still unknown. The present report showing that early Polish isolates appear antigenically original suggests that more diversity than currently admitted might have existed in Europe prior to the emergence of the vvIBDV. Such an assertion is in accordance with a recent report by Mato et al. (12) showing that several early Hungarian IBDV isolates collected in the late 70s and early 80s belong to a genetic cluster significantly different from the “classical” viruses. Analysis of more early IBDV isolates is necessary to get a more precise insight into the actual epidemiology of IBD. Acknowledgement: This work was supported by COST “Immunosuppressive viral diseases in poultry” from the EU. Action 839 51 References 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. Borzemska W., Golnik W.: Przypadek choroby Gumboro (Bursitis infectiosa) rozpoznany w Polsce, Medycyna Wet., 1969, 25, 644-645. Chettle, N.J., Stuart, J.C., Wyeth, P.J.: Outbreaks of virulent infectious bursal disease in East Anglia. Vet. Rec., 1989, 125, 271-272. Cosgrove A.S.: An apparently new disease of chickens-avian nephrosis. Avian Dis., 1962, 6, 385-389. Dobos P., Hill B.J., Hallett R., Becht H: Biophysical and biochemical characterization of five animal viruses with bisegmented double-stranded RNA genomes. J. Virol. 1979, 32, 593-605. Eterradossi N., Toquin D., Adam G., Picault J.P., Druin P., Guittet M., Bennejean G.: Proceedings from the International Symposium on Infectious Bursal Disease and Chicken Infectious Anaemia, Rauischholzhausen, Germany, 21-24 June 1994, 208. Eterradossi N.: Progress in the Diagnosis and Prophylaxis of Infectious Bursal Disease in Poultry. Comprehensive reports on technical items presented to the International Committee or to regional Commissions, OIE, Paris, 1995, 75-82. Eterradossi N., Toquin D., Rivallan G., Guittet M.: Modified activity of a VP2located neutralizing epitope on various vaccine, pathogenic and hypervirulent strains of infectious bursal disease virus. Arch. Virol., 1997, 142, 255-270. Eterradossi N., Rivallan G., Toquin D., Guittet M.: Limited antigenic variation among recent infectious bursal disease virus isolates from France. Arch. Virol., 1997, 142, 2079-2087. Eterradossi N., Arnauld C., Toquin D., Rivallan G.: Critical amino acid changes in VP2 variable domain are associated with typical and atypical antigenicity in very virulent infectious bursal disease viruses. Arch. Virol., 1998, 143, 1627-1636. Eterradossi N., Arnaud C., Tekaia F., Toquin D., Le Coq H., Rivallan G., Guittet M., Domenech J., van den Berg T.P., Skinner M.A.: Antigenic and genetic relationship between European very virulent Infectious Bursal Disease Viruses and an early West-African isolate. Avian Pathol., 1999, 28, 36-46. Jackwood D.J., Saif Y.M.: Antigenic diversity of infectious bursal disease viruses. Avian Dis., 1987, 31, 766-770. Lin Z., Kato A., Otaki Y., Nakamura T., Sasmaz E., Ueda S.: Sequence comparison of a highly virulent infectious bursal disease virus prevalent in Japan. Avian Dis., 1993, 37, 315-323. Mato T., Palya V., Lomniczi B.: Molecular characterization of Hungarian field isolates and vaccinal IBDV strains. COST Action 839 on Immunosuppressive Viral Diseases of Poultry: Proceedings 2000, 28-32. Mazurkiewicz M, Wachnik Z.: Zakaźne zapalenie torby Fabrycjusza u kurcząt Medycyna Wet. 1970, 26, 165-168. McFerran J.B., McNulty M.S., McKillop E.R., Conner T.J., McCracken R.M., Collins D.S., Allan G.M.: Isolation and serologic studies with infectious bursal disease virus from fowl, turkeys, and ducks: demonstration of a second serotype. Avian Pathol. 1980, 9, 395-405. Minta Z., Karczewski W., Roszkowski J.: Badania nad krajowym szczepem wirusa choroby Gumboro. Medycyna Wet., 1982, 38, 34-37. 52 17. Minta Z., Roszkowski J., Karczewski W., Kozaczyński W.: Properties of indigenous strains of infectious bursal disease virus. I. Identification. Bull. Vet. Inst. Pulawy, 1985-86, 28-29, 64-67. 18. Minta Z., Roszkowski J., Karczewski W., Kozaczyński W.: Properties of indigenous strains of infectious bursal disease virus. II. Pathogenicity. Bull. Vet. Inst. Pulawy, 1985-86, 28-29, 67-73. 19. Minta Z., Roszkowski J., Karczewski W., Kozaczyński W.: Properties of indigenous strains of infectious bursal disease virus. III. Immunosuppressive effect. Bull. Vet. Inst. Pulawy, 1985-86, 28-29, 73 -76. 20. Minta Z., Daniel A., Bugajak P., Kozaczyński W., Tomczyk G., Roszkowski J.: Current status of avian viral diseases in Poland, Proceedings 19th World’s Poultry Congress, Amsterdam, Holland, 19-24 September 1992, 37. 21. Minta Z., Daniel A.: Infectious bursal disease in Poland: current situation and vaccinal control. Proceedings Book from International Symposium on Infectious Bursal Disease and Chicken Infectious Anaemia, Rauischholzhausen, Germany, 21-24 June 1994, 208-214. 22. Minta Z., Daniel A., Kozaczynski W.: Characterization of infectious bursal disease virus strains isolated in Poland from acute outbreaks. Proceedings from World’s Poultry Congress, New Delhi, India, 2-5 September 1996, 326-327. 23. Nunoya T., Otaki Y., Tajima M., Hiraga M., Saito T.: Occurrence of acute infectious bursal disease with high mortality in Japan and pathogenicity of field isolates in SPF chickens. Avian Dis., 1992, 36, 597-609. 24. Pitcovski J., Goldberg D., Levi B.Z., Di-Castro D., Azriel A., Krispel S., Maray T., Shaaltiel Y.: Coding region of segment A sequence of a very virulent isolate of IBDV-comparison with isolates from different countries and virulence. Avian Dis., 1998, 42, 497-506. 25. Schnitzler D., Bernstein F., Müller H., Becht H.: The genetic basis for the antigenicity of the VP2 protein of the infectious bursal disease virus. J. Gen. Virol., 1993, 74, 1563-1571. 26. Snyder D.B., Lana D.P., Savage P.K., Yancey F.S., Mengel S.A., Marquardt W.W.: Group and strain-specific neutralization sites of infectious bursal disease virus defined with monoclonal antibodies. Avian Dis. 1988, 32, 527-534. 27. Snyder D.B., Vakharia V.N., Savage P.K.: Naturally occurring neutralizing monoclonal antibody escape variants define the epidemiology of infectious bursal disease viruses in the United States. Arch. Virol. 1992, 127, 89-101. 28. van den Berg T.P., Gonze M., Meulemans G.: Acute infectious bursal disease in poultry: isolation and characterization of a highly virulent strain. Avian Pathol., 1991, 20, 133-143. 29. van den Berg T.P., Gonze M., Morales D., Meulemans G.: Relevance of antigenic variation for protection in infectious bursal disease. Proceedings of the International symposium on infectious bursal disease and chicken infectious anaemia, Rauischholzhausen, Germany, 1994, 22-36. 30. van den Berg T.P, Eterradossi N., Toquin D., Meulemans G.: Infectious Bursal Disease (Gumboro Disease) In Diseases of Poultry: world trade and public health implications. OIE Scientific and Technical Review, special edition, 2000, 19, 509543. 31. van den Berg T.P.: Acute infectious bursal disease of chicken. A review. Avian Pathol., 2000, 29, 175-194.