Chemistry: molecular biology and microbiology – Measuring or testing process involving enzymes or... – Involving virus or bacteriophage
Reexamination Certificate
2000-08-11
2002-06-25
Salimi, Ali R. (Department: 1648)
Chemistry: molecular biology and microbiology
Measuring or testing process involving enzymes or...
Involving virus or bacteriophage
C424S229100, C424S204100, C424S184100
Reexamination Certificate
active
06410222
ABSTRACT:
The present invention relates to a prophylaxis for chicken Marek's disease induced by Marek's disease type I virus (hereinafter also referred to as “MDV-1”). More specifically, the present invention relates to a method for immunizing chickens comprising inoculating into a growing chicken egg either a composition comprising cell-free attenuated live MDV-1 or a composition comprising cells infected with attenuated live MDV-1 capable of producing cell-free viruses. Furthermore, the present invention provides a method for efficiently immunizing chickens against plural diseases with recombinant MDV-1.
BACKGROUND OF THE INVENTION
Marek's disease is a chicken infectious disease characterized by infiltration or tumorous proliferation of lymphoids by MDV-1 associated with symptoms such as leg paralysis, formation of lymphoma in various organs of viscera, weight loss, anemia, diarrhea, etc. In the field, Marek's disease leads chicken to death or partial or total disposal in a poultry laboratory and hence results in much economic loss in poultry farmer.
For protection from Marek's disease, attenuated live vaccine has hitherto been used, i.e. MDV-1, MDV-2 or herpes virus of turkey (HVT, MDV-3) alone or in admixture has been subcutaneously inoculated into newborn chicken. In such a case, a dosage form of virus-infected cells was usually employed. However, it was reported that as to Marek's disease virus with extremely high pathogenicity such as very virulent strain or very virulent (+) as reported in recent years, MDV-2 or HVT exhibits poor effectiveness but only vaccine of MDV-1 can effectively be used (R. L. Witter, AVIAN DISEASE 41: 149-163, 1997).
Nowadays, a number of vaccines have been developed for various chicken infectious diseases. Prophylaxis of diseases by vaccination is a ruling measure for sanitation in the field of poultry irrespective of breeding chicken, laying hen or chicken for meat. On the other hand, labor cost due to scale-up of poultry or crammed schedule of frequent inoculation of vaccine is a burden to poultry farmer. For obviating this, development of more effective and efficient vaccination such as reduction in frequency of inoculation by mixing several vaccines (i.e. mixed vaccine) or improvement of vaccination has been attempted.
As one of efficient way of vaccinations, Sharma et al. reported vaccination into growing chicken egg (“in ovo” inoculation) (J. M. Sharma et al., AVIAN DISEASE 26(1): 134-149, 1982). That is, according to Sharma et al., chicken hatched from a growing chicken egg inoculated with HVT-infected cells and chicken inoculated with said HVT after hatching were attacked by Marek's disease virus (hereinafter also referred to as “MDV”), and as a result, it was found that the chicken from vaccinated growing egg exhibited more potent resistance against the attack as compared to the chicken vaccinated after hatching, demonstrating that in ovo inoculation can effectively be used for immunization.
Reddy et al. prepared a recombinant HVT (rHVT) wherein a fusion protein (F protein) gene of Newcastle disease virus (hereinafter also referred to as “NDV”) and hemagglutinin-neuraminidase (HN) glycoprotein gene of NDV were incorporated into HVT genome (S. K. Reddy et al., Vaccine 14(6): 469-477, 1996). They inoculated cells infected with this virus into growing chicken egg on day 18. After hatching, the chicken was attacked by both NDV and MDV viruses to thereby demonstrate that the recombinant virus could effectively protect the chicken from the attack of both viruses. The effect of in ovo vaccination has also been estimated for an inactivated oil-emulsified vaccine of NDV and avian influenza virus (H. Stone, AVIAN DISEASE 41: 856-863, 1997) or for live Eimeria sporozoite vaccine (Evans et al., WO 96/40233).
Chicken immunization at the stage of growing egg as described above, called “in ovo vaccination”, can be expected to eliminate or reduce labor and cost and hence an automated device for inoculation into chicken egg becomes prevailing.
However, Sharma et al. reported that MDV-1-infected cells were inoculated into growing chicken egg and growth of said virus in chicken embryo tissue was investigated and, as a result, no viral growth was observed (J. M. Sharma et al., AVIAN DISEASES 31: 570-576, 1987). They also reported that chicken hatched from said growing egg was not protected from the attack of virulent MDV strain. This result suggests that in ovo vaccination against Marek's disease with MDV-1 is not so easy. Accordingly, it is the present situation that a univalent or mixed vaccine of HVT or MDV-2 SB-1 strain has alternatively been used as in place of MDV-1, a causing virus of Marek's disease.
On the other hand, there is a report of attempting to inoculate MDV-1, having been regarded as being ineffective for in ovo vaccination, into growing chicken egg (Taniguchi et al., 117th Japan Veterinary Science Association excerpt, p.198, 1994, Tokyo). In this case, if inoculation is made directly to fetus, the virus efficiently grew and successful immunization results. However, indeed, failure in direct inoculation to fetus frequently occurs. In spite of such circumstances, field application has been conducted because even if some individuals failed to be immunized, contact infection occurring about two weeks after MDV-1 inoculation would impart immunization to those individuals that failed to be immunized.
However, if non-immunized chicken is exposed to virulent MDV strain in the field after hatching and prior to infection with said MDV-1 vaccine by contact infection, then said chicken cannot be protected from Marek's disease and hence considerable economic loss will results. Thus, for thorough protection from Marek's disease, it is most important whether or not immunization is established within a week just after hatching. Accordingly, if possible, it is desirable to surely infect fetus in the growing egg with vaccine virus.
There is also a care that direct inoculation of needle into fetus might possibly damage the fetus badly in some cases.
Under the circumstances, there is a need to develop a more effective MDV-1 vaccine for Marek's disease that is applicable for in ovo vaccination.
DISCLOSURE OF THE INVENTION
The present inventors thoroughly investigated in order to develop a more effective MDV-1 vaccine for Marek's disease that is applicable for in ovo vaccination. As a result, it was found that a cell-free viral solution prepared from a solution of ruptured cells infected with either attenuated MDV-1 or recombinant MDV-1 was inoculated into growing egg to thereby exhibit viral growth. It was also found that antibodies to MDV-1 and to other viral antigens incorporated into MDV-1 were induced in serum of chicken that hatched from said virus-inoculated growing egg. As such, the present inventors have completed the present invention.
That is, an object of the present invention is to provide a method for immunizing chickens which comprises inoculating into growing egg a composition comprising either cell-free attenuated live MDV-1 or cells infected with attenuated live MDV-1 capable of secreting cell-free attenuated live MDV-1 out of the cells. The present invention also provides a method for efficiently immunizing chickens against plural diseases by using a recombinant MDV-1 in the above method for immunization.
Another object of the present invention is to provide a method for immunizing chickens which comprises inoculating into growing egg a mixed vaccine comprising the above cell-free MDV-1 plus another vaccine derived from at least one microorganisms selected from the group consisting of viruses other than MDV-1, bacteria and protozoan.
The method of the present invention is characterized by a composition comprising cell-free attenuated live MDV-1, a process for preparing the same and in ovo vaccination of said composition.
BEST MODE FOR CARRYING OUT THE INVENTION
The term “cell-free virus(es)” as used herein means viruses that are present in the state of being free from cells.
For
Sakaguchi Masashi
Tokunaga Eiji
Yokogawa Kenji
Birch & Stewart Kolasch & Birch, LLP
Juridical Foundation The Chemosero-Therapeutic Research Institut
Salimi Ali R.
LandOfFree
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