Thermostable Vaccine Research Articles

Thermostable newcastle disease vaccines in Tanzania

The V4 thermostable Newcastle disease vaccine was tested under village conditions in Central Tanzania. The vaccination regimes were four vaccinations by eye drop (eye drop group), one vaccination by eye drop followed by three vaccinations by drinking water (drinking water group), one vaccination by eye drop followed by three vaccinations with vaccine supplied on boiled sorghum (food vaccine group) and no vaccine (control group). Antibody responses in the eye drop and drinking water groups suggested that at least 70% of the chickens would be protected against challenge with virulent virus. In both groups, eight of the 11 chickens survived laboratory challenge. Only three of the 11 chickens in the food vaccine group resisted challenge, and none of the 10 control chickens.

Newcastle disease virus strain I 2 – a prospective thermostable vaccine for use in developing countries

Forty-five avirulent Australian strains of Newcastle disease virus had been examined for antigenicity in chickens and 18 of these were tested for thermostability. Strain I 2, chosen for a combination of antigenicity and thermostability, was artificially selected for enhanced thermostability. Master seed material was then prepared in minimal disease eggs, and vaccine by a further two passages in conventional eggs. Strain I 2 virus at seed and vaccine level induced adequate levels of antibody in chickens vaccinated by eye drop and usually in their contacts. The serological response to oral vaccination was less certain. Antibody titres indicative of substantial protection against virulent challenge were maintained in a simulated village flock for 38 weeks by vaccination of the foundation flock on two occasions, with subsequent vaccination confined to clutches of chicks as they were produced. Strain I 2 virus survived for at least 12 weeks when stored at 22°C in 1% gelatin. Strain I 2 is suitable for local production of thermostable vaccine in regional laboratories in developing countries.

Cellular immune response of a varicella vaccine following simultaneous DTaP and VZV vaccination

Background: Chickenpox and zoster are an important cause of morbidity among children and adults. The ability of a new, thermostable vaccine to induce varicella–zoster-virus (VZV)-specific humoral and cell mediated immunity when given simultaneously with diphtheria–tetanus-acellular pertussis vaccine (DTaP) as a booster dose in the second year of life was investigated. Methods: A new, temperature stable varicella vaccine (OKA-strain, SB-Biologicals, Rixensart, Belgium) was given simultaneously with a booster dose of DTaP vaccine. VZV-specific humoral and cell-mediated immunity was studied in the first 27 out of 232 vaccinated children at 16–28 months of age, from blood samples drawn just before and six weeks after vaccination. VZV-specific antibody response, T-cell proliferation, cytokine production and expression of activation markers (CD25, HLADR) on T-cells were analyzed. Results: Vaccination resulted in a significant rise of VZV-specific serum IgG titers and in a strong VZV-specific T-cell response in all vaccinated infants. Analysis of the expression of activation marker revealed activation of both CD4 +-T-helper- and CD8 +-T-cells. Conclusions: The varicella vaccine given simultaneously with DTaP produced strong B- and T-cell responses alike. This is the first report to show that CMI to VZV is conferred to young children by vaccination with a temperature stable VZV vaccine.

Vietnamese trials with a thermostable Newcastle disease vaccine (strain I 2) in experimental and village chickens

The Australian I 2 strain of Newcastle disease virus was tested as a vaccine in the laboratory and in Vietnamese villages. The infectivity titre of lyophilised vaccine fell less than 1 log 10 unit on storage for 6 days at 26–32°C. Vaccine stored at similar temperatures induced high levels of immunity in laboratory chickens after storage for 17 days and in village chickens after storage for 21 days. I 2 vaccine protected for at least 24 weeks after vaccination, and for 16 weeks after application in drinking water. Under laboratory conditions, I 2 vaccine given by eye drop spread by contact to unvaccinated chickens, inducing in them both an antibody response and protective immunity. In villages, chickens vaccinated by eye drop, chickens receiving vaccine on food and chickens in contact with vaccinated chickens all resisted artificial challenge 6 weeks after vaccination. There were no adverse reactions to vaccination. Strain I 2 was judged to be thermostable, avirulent and immunogenic, and suitable for use as a vaccine under village conditions.

Thermostabilization of live virus vaccines by heavy water (D 2O)

Eradication of poliomyelitis is based on the mass administration of oral poliovirus vaccine (OPV). Delivery of effective vaccines in the developing world, especially in tropical areas, is compromised when refrigeration cannot be assured. The OPV, prepared with three live attenuated polioviruses (Sabin strains, serotypes 1, 2 and 3), is considered to be the most thermolabile of vaccines in the World Health Organization's Expanded Programme on Immunization. To be effective, the initial concentration (potency) of each of the three component serotypes, measured in tissue culture infective doses, should not decrease by more than 0.5 log 10 before vaccine delivery. High concentration (1 M) of MgCl 2 is currently used as stabilizer for OPV. The stabilizing effect of D 2O was tested here on OPV strains. By diluting the viral suspension with D 2O-based salt and buffer solutions, in a manner similar to that involved in OPV production, an 87% concentration of D 2O in the final viral preparation was achieved. In severe conditions of testing (incubation for 3 days at 45°C), the Sabin 3 virus lost an average of 2.7 log 10 potency in the presence of 87% D 2O as compared to 3.0 log 10 in H 2O-based 1 M MgCl 2, and to 5.7 log 10 in the H 2O-based control solutions. When tested in a combined 87% D 2O and 1 M MgCl 2 treatment, the Sabin 3 virus lost only 1.3 log 10 potency after 3 days at 45°C. Similar thermostabilizing effects were obtained for Sabin 1 and Sabin 2 strains, but the level of stabilization was slightly lower. Tested in standard conditions at 37°C for 7 days, the infectivity of the three D 2O MgCl 2-treated OPV strains remained in the limit of requirements (≤0.5 log 10). The stabilizing effect of D 2O was also demonstrated on yellow fever 17D vaccine virus strain. D 2O, alone or in combination with other stabilizers such as MgCl 2, could thus be considered as a candidate for the improvement of live virus vaccine thermostability.

The thermostability of vaccines. Technologies for improving the thermostability of the oral poliovirus vaccine.

Technologies that promise to enhance the stability of vaccines are likely to be determined by the product-specific physical structure and biological functions of the specific vaccine immunogens. Research may define the extent to which the stability of oral poliovirus vaccine may be improved by the addition of certain antiviral components that bind to the poliovirus capsid or by the application of novel drying technologies.

The use of thermostable Vero cell-adapted rinderpest vaccine as a heterologous vaccine against peste des petits ruminants

The thermostable Vero cell-adapted rinderpest vaccine was evaluated in terms of immunogenicity as a heterologous vaccine against peste des petits ruminants. A titration to establish the minimum immunising dose was performed in American mixed breed goats by vaccinating test subjects with dilutions of Vero cell-adapted rinderpest vaccine and then challenging 26 days later with virulent peste des petits ruminants virus. All animals were followed for virus neutralising antibodies against both rinderpest and peste des petits ruminants virus after vaccination and challenge. The antibody response to vaccination was primarily against rinderpest virus with very low levels of cross-reactivity to peste des petits ruminants virus. Following challenge, animals which possessed anti-rinderpest neutralising antibodies remained clinically normal but mounted strong anti-peste des petits ruminants virus neutralising antibody responses indicating that replication of challenge virus took place without the induction of illness. The 50 per cent minimum goat immunising dose was 3 tissue culture infectious doses 50 per cent (TCID50) as established by serological response and protection against challenge. The thermostable Vero cell-adapted rinderpest vaccine is a suitable immunogen for the protection of goats against peste des petits ruminants.

Production of a thermostable vero cell-adapted rinderpest vaccine

The method of vaccine virus production, chemical stabilization, and lyophilization of a thermostable Vero cell-adapted rinderpest vaccine is presented. The production method results in a vaccine which can be used in the field without refrigeration for up to 30 d.

The thermal stability of yellow fever vaccines

The assessment of yellow fever vaccine thermostability both in lyophilized form and after reconstitution were analyzed. Two commercial yellow fever vaccines were assayed for their thermal stability. Vaccines were exposed to test temperatures in the range of 8 degrees C to 45 degrees C. Residual infectivity was measured by a plaque assay using Vero cells. The titre values were used in an accelerated degradation test that follows the Arrhenius equation and the minimum immunizing dose was assumed to be 10(3) particles forming unit (pfu)/dose. Some of the most relevant results include that (i) regular culture medium show the same degradation pattern of a reconstituted 17D-204 vaccine; (ii) reconstituted YF-17D-204 showed a predictable half life of more than six days if kept at 0 degrees C; (iii) there are differences in thermostability between different products that are probably due to both presence of stabilizers in the preparation and the modernization in the vaccine production; (iv) it is important to establish a proper correlation between the mouse infectivity test and the plaque assay since the last appears to be more simple, economical, and practical for small laboratories to assess the potency of the vaccine, and (v) the accelerated degradation test appears to be the best procedure to quantify the thermostability of biological products.

The serological response to a thermostable vero cell-adapted rinderpest vaccine under field conditions in Niger

A lyophilized thermostable Vero cell-adapted rinderpest vaccine, stabilized with lactalbumin hydrolysate and sucrose, was tested for safety, serological response and suitability for use with an abbreviated cold chain under field conditions in Niger. A total of 480 cattle, 90 goats and 55 sheep of unknown serological status were vaccinated on government ranches and observed for at least 22 days. No untoward effects of the vaccine were detected. The serological response to the vaccine stored at environmental temperatures for 30 to 34 days was determined in 144 previously unvaccinated yearling calves. Seroconversion was demonstrated in 98% of the yearling calves using seroneutralization. The un-refrigenated vaccine retained a titer of 3.69 log 10 TCID 10 per dose through day 34.

Multiple abnormalities in a child with partial duplications of 10p and 13q from a 3:1 segregation of a maternal t(10;13) translocation.

Partial duplications of 10p and 13q in association with partial deletions of other chromosome segments have been variously reported. We describe here a female child with multiple congenital abnormalities and combined partial duplications of 10p and 13q resulting from a 3:1 segregation of a maternal t(10;13)(p13;q22). In comparing the phenotypic features of the two chromosome imbalances, the expression of features typical of partial duplication 10p appeared more pronounced.

Determination of Efficacy of Thermostable PPR Live Homologous Vaccine Incubated at Room Temperature for 14 Days

The study was undertaken during the period from July to November 2005, for the first time, to determine the efficacy of thermostable PPR vaccine incubated at -20°C and room temperature (RT) for 14 days which was developed by Bangladesh Livestock Research Institute (BLRI), Savar, Dhaka, in collaboration with and Livestock Research Institute (LRI), Mohakhali, Dhaka. A total of 80 healthy goats of both sexes, aged between 8 to 36 months were divided into three groups as A, B and C. Group A and B comprised of 30 goats each and received thermostable PPR vaccine kept at -20°C and at room temperature (RT) respectively for 14 days, at a dose rate of 1 ml (4 Log10 TCID50 / ml) per goat subcutaneously while group C comprising 20 goats served as non-vaccinated control. At 30 days postvaccination, 3 goats from each vaccinated and non-vaccinated group were challenged with 1 ml (5 GID50) of virulent PPR virus per goat subcutaneously in the mid cervical region. Sera samples were collected from all the groups at pre- and post-vaccination (15 and 30 days postvaccination) and were tested for anti-PPR antibody by competitive enzyme linked immunosorbent assay (C-ELISA). In case of group A, average percent inhibition (PI) values of the sera samples at prevaccination and at 15- and 30 days post vaccination were 11.0 ± 5.7, 62.8 ± 9.9 and 81.5 ±5.9 respectively and in case of group B, were 10.0 ± 4.1, 60.7 ± 9.4 and 79.3 ± 7.2 respectively, which were significantly (p < 0.01) higher than those of non-vaccinated control goats (6.3 ± 3.4, 10.2 ± 3.3 and 13.6 ± 3.7 respectively). The titres of vaccinated goats gradually increased until 30 days postvaccination. The challenge test with virulent PPR virus at 30 days post vaccination showed that the thermostable PPR vaccine with both incubation temperatures at -20°C and RT for 14 days protected all the goats (100%) of groups A and B respectively while all the non-vaccinated control goats were not protected after challenge showing clinical signs of PPR and / or mortality. From the above findings it may be concluded that the thermostable PPR vaccine can be kept at normal environmental temperature (25°-30°C) as long as 14 days without loss of its potency and may be used to prevent PPR in goats in field condition.Key Words: Thermostable PPR vaccine, efficacy, C-ELISAdoi:10.3329/bjvm.v4i1.1524 Bangl. J. Vet. Med. (2006). 4 (1): 43-46