Cell Culture-derived Vaccine Research Articles

The influence of the type of immunosorbent on rabies antibody EIA; advantages of purified glycoprotein over whole virus

Two types of in vitro assay (enzyme immunoassay and seroneutralization test) for the titration of rabies antibodies were used to assay sera from mice and humans immunized with cell culture vaccines or neural tissue vaccines. Enzyme immunoassays (EIA) were performed in plates sensitized with whole virus, purified glycoprotein or purified nucleocapsid. Neutralizing antibody titres were determined by the rapid fluorescent focus inhibition test (RFFIT) and by an in vitro seroneutralization test including a rapid enzyme immunotitration of intracellular antigens (REITICA). The results obtained with sera of immunized mice and humans showed that (1) cell culture vaccines mainly induced the synthesis of antiglycoprotein neutralizing antibodies; and (2) neural tissue vaccines induced a high synthesis of antinucleocapsid non-neutralizing antibodies and a more or less important synthesis of antiglycoprotein antibodies depending on the origin of the tissue used for their preparation. Consequently, it was emphasized that when using EIA, the antibody titration must be run in glycoprotein-coated plates rather than in whole virus-coated plates to appreciate correctly the immunizing potency of a rabies vaccine, especially neural tissue vaccine.

Rabies vaccines produced in cell culture

Summary In 1953, Sanders et al. published the first trial of adapting rabies virus to cell culture. The adapting of rabies virus to diploid cells of human origin by Wiktor et al. in 1954 gave new possibilities. Other cell systems were then explored in different countries. A list of the cells recommended by the WHO Expert Committee was drawn up in 1974. The cell culture vaccines used regularly for human vaccination are classifiedaccording to their cell support: a ) primary cells of animal origin: cells from hamster kidney, fœtal calf kidney and dog kidney; b ) cells from bird embryos: chicken or quail; c ) diploid cells: essentially of human origin, WI38, then MRC5 and, on trial, rhesus diploid cells; d ) heteroploid cells: Vero cells. Three examples illustrate the points in common and the differences in the culturesystems and the corresponding vaccines: u -vaccines produced from human diploid cells, the most widely used in the world, acting as a reference for cell culture vaccines; -vaccines produced from fœtal calf kidney cells, an example of productionusing a primary animal cell system; -vaccines produced from Vero heteroploid cells, which paved the way to large-scale industrial production. Cell culture vaccines have transformed the possibilities of immunization beforeand after exposure. But these vaccines only account for 7% of antirabies treatment at present, with enormous variations, principally depending on the economic possibilities of the different regions of the world. Future development, based on the recommendations made in 1984 by the WHO Rabies Expert Committee, should resolve the technical and economic problems, making it possible to replace traditional vaccines by cell culture vaccines.

Schémas réduits de traitement antirabiqueavec les nouveaux vaccins de cultures cellulaires

Summary The original ≪Pasteur treatment≫ required long series of daily injections of rabbit medulla suspension of increasing virulence. Even with the Fermi and Semple types of inactivated sheep brain vaccines, these long series remained necessary, with a high risk of neuroparalytic accidents. The first possibility of using redu ced schedules of post-exposure vaccination appeared after 1955 with the sucklingmouse-brain vaccine. But it was only after 1965, with the newly developed cell culture vaccines, (mainly the human diploid cell vaccine), that a reduced schedule of rabies treatment of only 6 injections could be recommended by the WHO. This WHO scheme is now widely used with other cell culture vaccines in several countries. New reduced schedules of rabies post-exposure vaccination are presently under study with the aim of inducing an immune response as early as possible and, at the same time, reducing the amount of vaccine used (and thus the cost of vaccination) and the number of injections: the multi-site method and the intradermal route of injection have proven to be very efficient in this respect.

Field Vaccination against Hemorrhagic Enteritis of Turkeys by a Cell-Culture Live-Virus Vaccine

A cell-culture-propagated (CC) live-virus hemorrhagic enteritis (HE) vaccine was evaluated for efficacy and safety in two field trials conducted in North Carolina (NC) and Minnesota (MN). At 4 or 5 1/2 weeks of age, 9,839 poults in NC and 15,857 poults in MN were vaccinated with a CC HE vaccine administered via the drinking water. A comparable number of poults were maintained as unvaccinated controls. Vaccinated and unvaccinated poults were compared for seroconversion, response to laboratory challenge with a virulent HE virus at 3 weeks postvaccination, livability, percentage graded A, and average weight at marketing. In both trials, vaccination with the CC HE vaccine resulted in immunity against HE as indicated by seroconversion and by resistance to HE lesions following laboratory challenge with virulent HE virus. Compared with unvaccinated groups, vaccinated groups had a significantly higher percentage of turkeys graded A in the NC trial and in two of three flocks in the MN trial (P less than 0.005). Further, in the NC trial, livability was significantly higher (P less than 0.005) in vaccinated turkeys than in unvaccinated turkeys. These data indicate that the CC HE vaccine is efficacious and safe to use in the field.

Cross protection of mice against different rabies virus isolates

In an attempt to identify “atypical” strains which could account for vaccination failures, 10 street, one intermediate (DR19) and 4 fixed rabies virus isolates from men, cattle, dogs, cats, mongoose and vampire bats in five countries (Argentina, Brazil, Chile, Cuba, and France) were studied by cross-protection tests in mice. For the purpose of this study, any virus that killed more than 20 % of the vaccinated mice challenged with that virus was considered “atypical”. When the suckling mouse brain rabies vaccine was used, two “atypical” isolates were found: one, from a human case in Chile (91, 125 mouse passages) and the other, from a vampire bat in Brazil (DR19, 22 mouse passages). However, when mice immunized with a cell culture vaccine (PV-BHK) of a higher antigenic value than the brain vaccine, were challenged with those same isolates, mortality was below 20%. The fact that these two isolates killed enough vaccinated mice to be considered “atypical” could be related to antigenic differences between these viruses and those included in the vaccine. However, since this mortality was observed only in the mice immunized with the vaccine with a lower antigenic value, reasons are given why it could be attributed to other biological characteristics of those strains than antigenic differences. Causes for vaccines failures other than immunological differences of rabies virus strains are also analyzed and discussed.

Simple techniques for increasing the batch size of rinderpest cell culture vaccine.

Simple techniques for increasing the batch size of rinderpest cell culture vaccine.

The duration of immunity in cattle following inoculation of rinderpest cell culture vaccine.

The duration of immunity following a single administration of rinderpest cell culture vaccine, of 90 or more monolayer passages, was studied in E. African zebu (Boran) and grade (cross-bred European) cattle. All animals were kept for periods of 6-11 years in rinderpest-free environments; groups of them (in all 23 Borans and 10 grades) were then challenged by parenteral or intranasal inoculation of virulent virus or by contact exposure to reacting cattle. Nasal excretion of virus was studied daily over the 10-to 14-day period following challenge, and simultaneous attempts were made to detect viraemia. The neutralizing antibody response was followed at 6-month intervals over the whole post-vaccination period and then daily for 10 days and at longer intervals to 3 weeks after challenge. All 33 animals which were exposed by various routes failed to react clinically and a rinderpest viraemia was never detected. No transmission of virus from the vaccinates to susceptible in-contact controls occurred within 14 or more days, from the 20 animals which could be so tested. Clearcut serological responses to challenge were seen in six cattle (four Borans and two grades) which were challenged after 7 years or more; these reactions were all delayed to the 9th or 10th days, i.e. they were not typically 'anamnestic'. These results are discussed in relation to mass vaccination campaigns for the control of rinderpest and from the comparative viewpoint of measles vaccination in man.

Isolation and serotyping of porcine rotaviruses and antigenic comparison with other rotaviruses

Seven rotavirus strains were isolated in cell cultures from the intestinal contents of piglets with diarrhea. MA104 cells with pancreatin in the cell culture medium was the host system of choice for virus isolation and replication. A cell culture immunofluorescence test in which MA104 cells were used in microtiter plates was very effective for detecting and assaying rotaviruses. A plaque reduction neutralization test, cross-protection studies in gnotobiotic pigs, and electrophoresis of rotaviral double-stranded RNA were used for comparing viruses. Three strains produced plaques on initial isolation attempts, replicated well in cell cultures, and were antigenically very similar. We suggest that these three strains be considered porcine rotavirus serotype 1, with The Ohio State University (OSU) strain serving as the prototype. The OSU strain was distinct from bovine, simian, canine, and human (Wa and M) rotaviruses by plaque reduction neutralization. Four strains did not produce plaques on initial isolation attempts, were difficult to adapt to cell cultures, and were related to each other but were distinct from the serotype 1 strains. We suggest that the Gottfried (G) strain be tentatively considered as a prototype for porcine rotavirus serotype 2. The G strain was antigenically closely related to canine and simian rotaviruses and less so to human M rotavirus (human rotavirus serotype 3). Canine, simian, and human M rotaviruses were closely related. All seven porcine rotavirus strains caused diarrhea in gnotobiotic pigs. Cell-cultured vaccines of the OSU and G strains caused only mild or no diarrhea in gnotobiotic pigs, and protection occurred when such pigs were challenged with homologous, bur not heterologous, virulent viruses. A survey indicated that 94% of 274 porcine serum samples and 100% of 75 herds were serologically positive to the porcine OSU rotavirus.

Efficacy and Safety of a Cell-Culture Live Virus Vaccine for Hemorrhagic Enteritis of Turkeys: Laboratory Studies

Poults free from hemorrhagic enteritis (HE) antibody were vaccinated by gavage at 1 day or 2 weeks of age with a live HE vaccine virus that had been propagated in a Marek's disease (MD)-induced B-lymphoblastoid cell line of turkey origin. Vaccinated and unvaccinated poults were challenged with a virulent HE virus at various times postvaccination. One hundred tissue-culture-infectious doses of the vaccine virus per poult were sufficient to induce a serological response as well as to protect poults against HE lesions and mortality. Vaccinated poults were protected against the disease as early as 1 week and as late as 8 weeks PV. The vaccine was efficacious by several routes of application. The vaccine virus spread horizontally from vaccinated to contact-exposed poults, as indicated by seroconversion and resistance of contact-exposed poults to challenge. The vaccine had no detectable harmful effects on the humoral immune response to particulate antigens or on weight gain of vaccinated poults. The vaccine proved to be free from MD virus, as indicated by the absence of MD lesions and antibody in 8-week-old chickens inoculated intra-abdominally with the vaccine at hatching. These findings indicate that the cell-culture-propagated HE vaccine is efficacious and safe.

Towards global eradication of rinderpest.

Summary: Rinderpest is still the greatest scourge of domestic cattle and buffaloes in tropical Africa and Asia. Despite large-scale mass vaccina­ tion campaigns, outbreaks of the disease continue to spread to countries from where it was once eradicated. During the past few years an increased incidence of the disease has affected several countries in West, East and Central Africa, the Middle East and South-East Asia. The Sahelian drought this year might force large-scale migration of cattle from Chad and Mali, and thereby increase the spread of the disease to countries south of Sahara. Currently a panzootic of rinderpest is sweeping across tropi­ cal Africa, and an epidemiologist has already claimed that a million cattle have died or been emergency slaughtered. This calamity coupled with drought, famine and political strife has resulted in a disaster of the century. Global eradication of smallpox has shown that it is possible to eradic­ ate a disease by human endeavour. Rinderpest is also a severe disease of domestic cattle and is of great economic significance. It does not pro­ duce persistent, recurrent and subclinical infection, and a safe and effec­ tive cell-culture vaccine is available. With international financing and organisation, global eradication of rinderpest should be possible within a period of a few years. The paper describes the present situation of the disease, efforts made to control and eradicate it in the recent past, and suggests ways and means to achieve these goals.

‘Red Book’ Update

UPDATE The Red Book Committee met on May 10, 1982 and considered a number of issues, including: 1. The 1982 edition (19th) of the Red Book has been distributed beginning on June 4, 1982. We welcome comments and suggestions for the 20th edition. 2. IMPORTANT REVISION IN RED BOOK RECOMMENDATIONS: After the Committee meeting it came to our attention that three children who had anaphylactoid reactions to egg ingestion experienced immediate allergic reactions to chick-embryo-grown live measles virus vaccine; two had difficulty breathing and one had hypotension. Persons who are egg-allergic but do not have a history of anaphylactoid reactions appear to be at little or no risk from live measles virus (LMV) vaccine (See Morbidity Mortality Weekly Rep 31:217-231, May 7, 1982). Because previous experience indicated no adverse reactions in egg-allergic children given vaccine prepared in chick embryo tissue culture, the 1982 Red Book contains the following statement: The vaccine currently used in the United States is prepared in chick embryo tissue culture by inoculation with a further attenuated passage of the Edmonston B strain of measles virus. This preparation is virtually devoid of allergenic substances derived from the chick embryo cell cultures used for growth of the live vaccine viruses. However, there is a remote potential risk of hypersensitivity reactions in patients allergic to eggs, chicken, or chicken feathers; large scale use of the vaccine for more than a decade has resulted in only rare, isolated reports of minor allergic reactions. In a study in which children known to be allergic to eggs, chicken, or chicken feathers were vaccinated with a chick embryo cell culture-derived vaccine, no allergic reactions were observed.

Booster Effect of Human Diploid Cell Antirabies Vaccine in Previously Treated Persons

Contact was maintained with 27 of 45 persons for four years after their severe exposure to rabies virus and successful protection. During that time, these persons showed no adverse effects of treatment and maintained rabies-neutralizing antibody at the level of 2 to 91 IU/mL of serum. After a single booster inoculation of human diploid cell culture vaccine four years after the initial treatment, levels of neutralizing antibodies rose to 36 to 650 IU/mL of serum ten days after the booster inoculation. These observations confirm the persistence of rabies-specific serum antibodies for an extended (four years) period after vaccination. Furthermore, a single booster inoculation with human diploid cell culture vaccine resulted in a sharp increase in the level of antibodies, indicating that a person would probably be protected against a second exposure.

12 - Immunization

LC16m8 is a live, attenuated, cell-cultured smallpox vaccine that was developed and licensed in Japan in the 1970s, but was not used in the campaign to eradicate smallpox. In the early 2000s, the potential threat of bioterrorism led to reconsideration of the need for a smallpox vaccine. Subsequently, LC16m8 production was restarted in Japan in 2002, requiring re-evaluation of its safety and efficacy. Approximately 50,000 children in the 1970s and about 3500 healthy adults in the 2000s were vaccinated with LC16m8 in Japan, and 153 adults have been vaccinated with LC16m8 or Dryvax in phase I/II clinical trials in the USA. These studies confirmed the safety and efficacy of LC16m8, while several studies in animal models have shown that LC16m8 protects the host against viral challenge. The World Health Organization Strategic Advisory Group of Experts on Immunization recommended LC16m8, together with ACAM2000, as a stockpile vaccine in 2013. In addition, LC16m8 is expected to be a viable alternative to first-generation smallpox vaccines to prevent human monkeypox.

Vaccination of Children With Human Cell Culture Rabies Vaccine

Three children exposed to the bites of proved or probably rabid animals were immunized with human rabies immune globulin and human diploid cell culture vaccine. There were no significant clinical reactions, and all three developed high levels of rabies antibody. The patients have remained well from four to 18 months.

The development and evaluation of a cell culture vaccine against infectious laryngotracheitis virus

The development and evaluation of a vaccine against infectious laryngotracheitis virus (ILTV) using an avirulent Australian strain propagated in chicken embryo kidney cell culture is described. Yields of cell culture-grown vaccine virus per embryo were at least as high as yields obtained by the Chorio-allantoic Membrane (CAM) method. Freeze-dried preparations of stabilized cell culture vaccine showed no loss in infectivity after storage at 4°C for 12 months. In a dose-response trial using 9-day-old ILTV-susceptible chickens vaccinated by the ocular route, the 50% protective dose against challenge with virulent ILTV was shown to be approximately 100 plaque-forming units per bird.

Immunoglobulin (IgG) and (IgM) antibody responses to rabies vaccine.

IgM and IgG neutralizing antibody responses were estimated in the sera of rabbits and mice immunized with different doses of Semple, duck embryo and cell culture rabies vaccines. IgM synthesis was prolonged in animals immunized with multiple doses of either Semple or duck embryo vaccines but not those immunized with cell culture vaccine. Mice were passively protected by IgG antibody against subsequent challenge but not by IgM of equivalent neutralizing titre. Mice challenged when the antibody response was solely IgM were not protected if the transition to IgG synthesis was prevented by cyclophosphamide treatment.

A cell culture vaccine against bovine ephemeral fever.

A vaccine was prepared from cell culture fluids harvested from the twelfth passage of the 919 strain of bovine ephemeral fever (BEF) virus in Vero cell cultures. Cattle were vaccinated subcutaneously with various combinations of strain 919 virus and adjuvants. Neutralising antibodies were assayed at various times after vaccination and some cattle were challenged by intravenous inoculation with the virulent 417WBC strain of BEF virus. Strain 919 virus of the third and twelfth passage levels in Vero cells produced neither fever, clinical illness nor detectable viraemia in 5 calves inoculated intravenously. Nor could viraemia be detected in 5 heifers receiving vaccine subcutaneously. When the vaccine was administered mixed with aluminium hydroxide adjuvant, the production of neutralising antibodies increased with an increase in the volume of vaccine from 2.5 ml to 10 ml and the response to 2 injections was significantly better than the response to a single injection. The neutralising antibody response was decreased when vaccine was diluted in phosphate buffered saline. The neutralising antibody response following 2 subcutaneous vaccinations with strain 919 virus mixed with aluminium hydroxide adjuvant was higher than that following intravenous inoculation with virulent virus. The vaccine-induced antibodies persisted for at least 12 months, and revaccination at this time led to an increase in the titre of neutralising antibody. Antibodies induced by a single subcutaneous administration of strain 919 virus mixed with Freund's complete adjuvant persisted for at least 40 weeks; those induced by vaccine containing Freund's incomplete adjuvant had virtually disappeared within 16 weeks. All these calves responded to vaccination with aluminium hydroxide-containing vaccine with increases in levels of neutralising antibodies. Of 26 vaccinated calves challenged with virulent BEF virus, 24 remained clinically normal. Two developed brief periods of pyrexia on the seventh day after challenge, but no other clinical signs. One of these calves had a viraemia that was demonstrated only by intravenous inoculation of a susceptible calf. The remaining calf had no detectable viraemia. All of 7 unvaccinated calves developed severe clinical BEF within 5 days of challenge. No disease attributable to the 919 virus occurred in 24 vaccinated pregnant heifers or their newborn calves.

Immunization of Pheasants for Eastern Encephalitis

Pheasants vaccinated twice with as much as one-half horse dose of a commercial Eastern-Western encephalitis adjuvanted cell-culture vaccine did not develop significant hemagglutination-inhibition titers and were not protected against artificial challenge by an Eastern encephalitis virus.

Prophylactic immunization of humans against rabies by intradermal inoculation of human diploid cell culture vaccine.

The antirabies human diploid cell vaccine produced by 1'Institute Merieux, Lyon, France, was administered intradermally to 35 high-risk volunteers using 0.2-ml amounts and various immunization schedules. Three groups never before vaccinated against rabies developed virus-neutralizing antibodies, the titer of which was dose dependent. A single injection stimulated the formation of antibodies. Four inoculations induced the highest antibody levels and the longest persistence of antibody. The administration of a single intradermal booster inoculation was sufficient, even in the case of low-persisting antibody, to elicit a rapid increase of antibodies to high levels. A primary inoculation course of two injections induced a sufficient antibody level which, in case of exposure, could apparently be rapidly elevated by a 0.2-ml intradermal booster inoculation. Adverse side reactions were observed in 7 of 14 individuals after a 1- or 1.5-year intradermal booster inoculation. We therefore suggest that the intramuscular and subcutaneous routes continue to be used for primary vaccinations and that the highly effective intradermal route be restricted to booster inoculations. This is the first long term study of this vaccine and should be a guideline for the pre-exposure treatment of high-risk personnel.

The Addition of Fowlpox and Pigeon Pox Vaccine to Marek's Vaccine for Broilers

Laboratory and field studies indicated that a cell-culture fowlpox vaccine was effective and safe when administered subcutaneously to day-old broiler chicks in combination with cell-associated Marek's vaccine without compromising the latter. Pox vaccines of chick embryo origin evaluated similarly provided excellent protection, although they caused local musculature swelling when injected into muscle rather than under the skin. No muscle swelling followed improper vaccination with the cell-culture fowlpox vaccine.