Characterization of the RDC1 gene which encodes the canine homolog of a proposed human VIP receptor. Expression does not correlate with an increase in VIP binding sites

Matrix and backstage: cellular substrates for viral vaccines

Vaccines are complex products that are manufactured in highly dynamic processes. Cellular substrates are one critical component that can have an enormous impact on reactogenicity of the final preparation, level of attenuation of a live virus, yield of infectious units or antigens, and cost per vaccine dose. Such parameters contribute to feasibility and affordability of vaccine programs both in industrialized countries and developing regions. This review summarizes the diversity of cellular substrates for propagation of viral vaccines from primary tissue explants and embryonated chicken eggs to designed continuous cell lines of human and avian origin.

History of polio vaccination

Poliomyelitis is an acute paralytic disease caused by three poliovirus (PV) serotypes. Less than 1% of PV infections result in acute flaccid paralysis. The disease was controlled using the formalin-inactivated Salk polio vaccine (IPV) and the Sabin oral polio vaccine (OPV). Global poliomyelitis eradication was proposed in 1988 by the World Health Organization to its member states. The strategic plan established the activities required for polio eradication, certification for regions, OPV cessation phase and post-OPV phase. OPV is the vaccine of choice for the poliomyelitis eradication program because it induces both a systemic and mucosal immune response. The major risks of OPV vaccination are the appearance of Vaccine-Associated Paralytic Poliomyelitis cases (VAPP) and the emergence of Vaccine Derived Polioviruses strains. The supplementary immunization with monovalent strains of OPV type 1 or type 3 or with a new bivalent oral polio vaccine bOPV (containing type 1 and type 3 PV) has been introduced in those regions where the virus has been difficult to control. Most countries have switched the schedule of vaccination by using IPV instead of OPV because it poses no risk of vaccine-related disease. Until 2008, poliomyelitis was controlled in Romania, an Eastern European country, predominantly using OPV. The alternative vaccination schedule (IPV/OPV) was implemented starting in September 2008, while beginning in 2009, the vaccination was IPV only. The risk of VAPP will disappear worldwide with the cessation of use of OPV. The immunization for polio must be maintained for at least 5 to 10 years using IPV.

Immunity status of adults and children against poliomyelitis virus type 1 strains CHAT and Sabin (LSc-2ab) in Germany

BACKGROUND

In October 2007, the working group CEN/TC 216 of the European Committee for standardisation suggested that the Sabin oral poliovirus vaccine type 1 strain (LSc-2ab) presently used for virucidal tests should be replaced by another attenuated vaccine poliovirus type 1 strain, CHAT. Both strains were historically used as oral vaccines, but the Sabin type 1 strain was acknowledged to be more attenuated. In Germany, vaccination against poliomyelitis was introduced in 1962 using the oral polio vaccine (OPV) containing Sabin strain LSc-2ab. The vaccination schedule was changed from OPV to an inactivated polio vaccine (IPV) containing wild polio virus type 1 strain Mahoney in 1998. In the present study, we assessed potential differences in neutralising antibody titres to Sabin and CHAT in persons with a history of either OPV, IPV, or OPV with IPV booster.

METHODS

Neutralisation poliovirus antibodies against CHAT and Sabin 1 were measured in sera of 41 adults vaccinated with OPV. Additionally, sera from 28 children less than 10 years of age and immunised with IPV only were analysed. The neutralisation assay against poliovirus was performed according to WHO guidelines.

RESULTS

The neutralisation activity against CHAT in adults with OPV vaccination history was significantly lower than against Sabin poliovirus type 1 strains (Wilcoxon signed-rank test P < 0.025). In eight sera, the antibody titres measured against CHAT were less than 8, although the titre against Sabin 1 varied between 8 and 64. Following IPV booster, anti-CHAT antibodies increased rapidly in sera of CHAT-negative adults with OPV history. Sera from children with IPV history neutralised CHAT and Sabin 1 strains equally.

CONCLUSION

The lack of neutralising antibodies against the CHAT strain in persons vaccinated with OPV might be associated with an increased risk of reinfection with the CHAT polio virus type 1, and this implies a putative risk of transmission of the virus to polio-free communities. We strongly suggest that laboratory workers who were immunised with OPV receive a booster vaccination with IPV before handling CHAT in the laboratory.

Poliomyelitis Immunization: Mass use of oral vaccine in the United States might prevent definitive evaluation of either vaccine

I would summarize the foregoing discussion by asserting, first, that the superiority of the live oral attenuated poliovirus vaccines over the inactivated vaccines now in use remains to be demonstrated, except for convenience of administration. Second, the proposal to introduce live oral poliovirus vaccine by means of country-wide mass immunization programs is irresponsible in the sense that such a procedure would eliminate the possibility of a definitive evaluation of either vaccine in this country, and moreover is unlikely to accomplish more than can be accomplished by a more conservative approach. Third, even after licensing, a new vaccine product must be considered to be on trial, since new variables enter the scene when large-scale manufacture and large-scale use begin. In this connection it is of importance that the margin of safety of live-attenuated-poliovirus lots now in production is not large, as measured by the only laboratory test available-neurovirulence in monkeys. In comparison with unacceptable trial strains, about which questions of safety have been raised after field use, the acceptable strains have measurably less neurovirulence, but the differences are not great, and approval of each lot will require careful scrutiny for evidence of even slight degrees of reversion in neurovirulence during production. Finally, there is a place for both types of vaccine in the control of poliomyelitis throughout the world. How and where each type should be used is a scientific problem which can best be resolved with careful assessment of all the available evidence concerning vaccine characteristics in relation to the ecology of poliomyelitis. From the point of view of a scientific evaluation of the results of the present waccination program in this country, it appears that a quip I made in 1960 (13)-we may now have too many poliomyelitis vaccines!-has come home to roost.

Oral delivery of replication-competent adenovirus vectors is well tolerated by SIV- and SHIV-infected rhesus macaques

Although replication-competent adenovirus (Ad) vectors are promising in AIDS vaccine design, their safety in immune compromised hosts is unknown. To initially address this question, enteric-coated tablets containing a replicating Ad vector were orally administered to SHIV- and SIV-infected rhesus macaques with normal, intermediate or low CD4 T cell counts and stable disease. The vector was detected within a week after tablet administration in stools of all animals but not in nasal secretions, indicating no spread of virus to the upper respiratory tract. CD4 T cell counts and viral loads remained stable in all animals and no signs of fever, weight loss, or other clinical symptoms of Ad-induced disease were observed during 10 weeks of follow-up. Oral delivery of the replicating Ad vector was safe and well tolerated by SHIV- and SIV-infected hosts. Oral enteric-coated tablets may prove safe for administering replicating Ad-vectored vaccines in areas with high HIV prevalence.

Sabin monovalent oral polio vaccines: review of past experiences and their potential use after polio eradication

After global eradication of polio is achieved, there will be a need for stockpiles of vaccine to combat potential outbreaks of poliomyelitis caused by (1) unforeseen release of polioviruses, (2) continued circulation of vaccine-derived strains, or (3) prolonged replication of polioviruses in immunodeficient persons. We conducted a review of the literature to document the immunogenicity and safety of monovalent Sabin vaccines, considered ideal candidates for these situations. The National Library of Medicine archives were searched for the keywords "polio," "monovalent," and "vaccine." Seroconversion rates for monovalent Sabin type 1 ranged from 53% to 100% (median, 95%); for type 2, 77%-100% (median, 93%); and for type 3, 52%-100% (median, 85%). The risk of vaccine-associated poliomyelitis per million persons vaccinated ranged from.05 to 0.99 (type 1), 0-0.65 (type 2), and 1.18-8.91 (type 3). Single-dose monovalent Sabin vaccines are highly immunogenic and safe and should be considered for stockpiles of vaccine to provide an effective response to potential outbreaks of poliomyelitis in the post-eradication period.

An aluminum marker for the differentiation and separation of virulent and attenuated polioviruses

A new character, the A marker, for polioviruses is described. In the presence of Al(+++) (1 to 100 mM) attenuated, but not virulent, strains of type 1 and type 2 polioviruses are stabilized so that they resist thermal inactivation at 50 degrees C. Differences between the attenuated and virulent type 3 strains studied were of the opposite character and less marked. By the use of optimal concentrations of Al(+++) (12 mM for type 1 and 1 mM for type 2) attenuated strains can be separated from mixtures containing virulent type 1 or 2 strains. The A marker was found to be correlated with the d but not the rct/40 or T marker. The A marker has been used for following genetic changes of vaccine strains after their multiplication in man.

Current status of poliovirus infections

Two scientists who played leading roles in the conquest of poliomyelitis died recently. In 1954, Jonas Salk provided the first licensed polio vaccine, the formalin (and heat)-inactivated virus. Albert Sabin gave us the attenuated live virus vaccine, which was licensed in 1962. This paper takes the reader through the history of the disease, including its pathogenesis, epidemiology, vaccines, and future directions. The emphasis is on vaccines, for it seems that with proper vaccination the number of new cases is falling dramatically. It is hoped that by the year 2000, we will accomplish the goal of the World Health Organization of "a world without polio." Then, because there is no animal reservoir, we can seriously discuss when and how to eliminate the need for vaccination and ultimately destroy our stocks of poliovirus.

Control of influenza and poliomyelitis with killed virus vaccines

The requirements for inducing immunity against an infectious disease are outlined, and the application of these requirements to the development of effective vaccines (vaccinology) is discussed. Influenza and poliomyelitis are examined from this viewpoint, and data are presented that demonstrate the effectiveness of killed virus vaccines against these diseases. A comparison between live and killed poliovirus vaccines suggests the desirability of returning to the use of a killed virus vaccine for the eradication of polio. The natural history of influenza and experience with vaccination suggest that influenza might be brought under effective control by routine immunization in childhood with a polyvalent killed virus vaccine potentiated by an immunologic adjuvant.

Identificação sorológica intratípica de poliovírus pelo "método da comparação dos índices de neutralização"

O método da comparação dos índices de neutralização (SMIT & WILTERDINK, 1966) foi utilizado na identificação sorológica intratípica de 49 poliovírus, pertencentes aos três tipos imunológicos e isolados de casos clínicos com e sem contato conhecido com a vacina oral de Sabin. O método foi também comparado com o método de Wecker e com o marcador RCT40 no estudo da identificação intratípica das estirpes do tipo 3. Os soros imunes necessários às reações de neutralização foram preparados em cobaias com as estirpes vacinais LSc2ab, P712Ch2ab e Leon 12a1b. As estirpes - dos tipos 1 e 3 - isoladas dos indivíduos sem contato conhecido com a vacina oral, foram todas identificadas como heterólogas às respectivas estirpes vacinais e as provenientes dos indivíduos com contato (recém-vacinados e contatos) foram identificadas como isólogas às respectivas estirpes vacinais, exceto duas, das quais uma (do tipo 1) foi identificada como intermediária e a outra (do tipo 3) como heteróloga. Não foi possível interpretar convenientemente os resultados das provas de identificação das estirpes do tipo 2, porque o índice de neutralização do protótipo Lansing, ao contrário dos índices das estirpes de referência dos tipos 1 e 3, não deu resultados constantes em provas consecutivas na presença do sôro anti-P712Ch2ab. No estudo da identificação intratípica dos poliovírus do tipo 3, o método da comparação dos índices de neutralização forneceu resultados plenamente concordantes com os obtidos pelo método de Wecker, com isto evidenciando ser um método igualmente satisfatório e, devido à relativa simplicidade de sua técnica, melhor indicado para inquéritos epidemiológicos, quando se examina a procedência de numerosas estirpes. Os resultados obtidos com o marcador RCT40 mostraram a importância de utilizar provas de diferenciação sorológica intratípica na identificação dos vírus da poliomielite em áreas de vacinação, devido à instabilidade do caráter RCT40 das estirpes do tipo 3.

Isolamento e identificação intratípica de cêpas de poliovirus associadas com a administração de vacina Sabin

Estudou-se a taxa de excreção de enterovírus em dois grupos de crianças de 1 a 4 anos de idade, que receberam várias doses de vacina Sabin. No primeiro grupo a colheita de fezes foi feita 60 dias após a administração da última dose de vacina e no segundo grupo, passados somente 15 dias. No primeiro grupo as porcentagens de isolamento de poliovírus e outros enterovírus foram, respectivamente, de 12,12% e 13,63%. já no segundo, estas porcentagens foram de 37,61% e 9,17%. Em ambos os grupos foram isolados os três tipos sorológicos de poliovírus. As taxas de isolamentos de poliovírus e outros enterovírus não se mostraram estatìsticamente diferentes, em ambos os grupos, quando relacionadas com o número de doses de vacina recebidas - duas ou menos doses e três ou mais doses. A identificação intratípica das cêpas de poliovirus isoladas foi feita pelos "marcadores" RCT40 e ds. Das 8 cêpas isoladas do primeiro grupo, 6 foram identificadas como intermediárias e 2 como cêpas naturais. Estas 2 cêpas foram isoladas das duas únicas crianças que não tinham sido vacinadas contra a poliomielite. Das 41 cêpas isoladas do segundo grupo, 8 foram caracterizadas como intermediárias e 33 como ceêpas tipicamente vacinais.

Reduction in plaque size and reduction in plaque number as differing indices of influenza virus-antibody reactions

Jahiel, R. I. (Cornell University Medical College, New York, N.Y.), and E. D. Kilbourne. Reduction in plaque size and reduction in plaque number as differing indices of influenza virus-antibody reactions. J. Bacteriol. 92:1521-1534. 1966.-The serological reactivity of an antigenically hybrid influenza virus recombinant (X-7) was studied in a heteroploid cell plaquing system in which antisera to the parental viruses NWS/(A(0)) and RI/5(+) (A(2)) were incorporated in agar overlay media. Two different effects on plaque formation were found. With NWS antiserum, there was close relationship between reduction in plaque size and in plaque number [plaque inhibition (PI) pattern]. With RI/5 antiserum, plaque size reduction (PSR) occurred over a wide zone of serum dilutions without concomitant change in plaque number (PSR pattern). Several different preinoculation neutralization tests showed a strong reactivity of X-7 with NWS antisera and little if any reactivity with RI/5 antisera. We interpret the differing effects of NWS and RI/5 antisera on X-7 as indicative of the possible occurrence of different mechanisms of neutralization or of the possible participation of different surface antigens. The kinetics of PSR are consistent with the hypothesis that it results from the reaction of RI/5 antiserum with the RI/5-like neuraminidase of X-7. Studies with the antiserum-in-overlay technique of PSR and PI patterns comprise a sensitive method for quantitative antigenic analysis of plaque-forming influenza viruses.