STABILIZED VACCINE COMPOSITIONS

Abstract: Vaccine compositions which contain a virus and, as stabilizer, a compound containing at least two amino groups. The stabilizers include diamines such as the amino acid lysine or ethylenediamine and polyamines such as poly(ethylenimine).

Description: STABILIZED VACCINE COMPOSITIONS Description Background of the Invention The trivalent oral polio vaccine (Sabin) is a live-attenuated virus vaccine. It is heat-labile and hence must be stored frozen and used soon after thawing to insure effective immunization against poliomyelitis. Although 1 molar magnesium chloride is an effective stabilizer for the Sabin vaccine, inactivation will still occur if the vaccine thaws during transport or storage. Because of the short¬ age of adequate refrigeration facilities in under¬ developed and tropical regions, where poliovirus is endemic, the vaccine often cannot be stored frozen and as a consequence the vaccine becomes inacti¬ vated. This leads to under-immunization of the populations which are most at risk. Thus, eradi¬ cation of poliomyelitis depends on the ability to assure cold storage and rapid distribution of poliovirus vaccine. Vaccine formulations with improved stability would circumvent this problem. Summary of the Invention This invention pertains to stabilized viral vaccines, particularly live viral vaccines for poliomyelitis, comprising an aqueous solution of a live virus and a stabilizing amount of a compound containing at least two amino groups, such as basic amino acids (e.g. lysine) . These compounds are safe, relatively inexpensive and can be easily added to viral vaccine preparations. The polyamino compound improves the heat stability of the virus in standard tests for viral stability over that of the currently available stabilizer magnesium chloride. This provides more stable live viral vaccine com¬ positions for worldwide distribution and use. Brief Description of the Figures Figure 1 shows stabilization of poliovirus (serotype 1, Mahoney strain) against heat inactiva¬ tion by 1 M amino acids or MgCl,. Poliovirus 4 X 10 8 plaque forming units (PFU, approximately 80 viral particles) was added to l ml of 5 mM phosphate buffer, pH 7.0, containing 1 M each of L-lysine (■) , L-arginine (x) , glycine ( ) , L-alanine (+) or MgCl (•) . The resultant solution was placed in 1.4 ml Eppendorf tubes, sealed and submerged in a water bath at 50 °C. Aliquots were removed periodically, diluted- ith with 5 mM phosphate buffer containing 150 mM NaCl, pH 7.0 (PBS), and the titer of infec¬ tious poliovirus was followed by plaque assay on HeLa cells. Figure 2 shows stabilization of poliovirus (serotype 1, Mahoney strain) against heat inactiva- tion by 1 or 2 M L-Lysine or MgCl . Poliovirus (8 X 10 8 PFU) was added to 1 ml of 5 mM phosphate buffer, pH 7.5, alone (A) or containing 1 M L-lysine (•) , 2 M L-lysine (n), 1 M MgCl (•) or 2 M MgCl 2 (o) . The resulting solution was placed in 1.4 ml Eppendorf tubes, sealed and submerged in a water bath at 50 °C. Aliquots were removed periodically, diluted with PBS, and the titer of infectious poliovirus was followed by plaque assay on HeLa cells. Detailed Description of the Invention The vaccine compositions of this invention comprise a virus and a compound, containing at least two amino groups, in an amount sufficient to stabil¬ ize the virus. The amino compound enhances the sta- bility of the virus against heat inactivation. For example, in standard tests for virus stability at 50°C, the stability of the virus is enhanced at least 10-20 fold by the amino acid lysine. The vaccine compositions are produced by adding the virus and a stabilizing amount of the amino compound into physiologically acceptable aqueous solution. The amino compound can be any non-toxic com¬ pound containing at least two amino groups. Pre¬ ferably, the compounds comprise at least two primary or secondary amino groups separated by a spacer moiety. The size or constituency of the spacer moiet does not appear to be critical. Typically, the spacer moiety will consist of a substituted or unsubstituted, linear chain of carbon atoms (heteroatoms such as nitrogen may be included in the chain) ranging from 1 to about 10, preferably from 1 to about 6 atoms. Preferred compounds are the amino acids lysine and arginine or salts (e.g., chloride or acetate) thereof. Some examples of other useful compounds include dia inoethane, 1,3-diaminopropane, 1,4-diaminobutane, and 1,5-diaminopentane. Other stabilizers include compounds which have a nitrogen carrying spacer moiety such as spermidine. In addition, polyamines such as poly(ethylenimine) can be used. Mixtures of amino containing compounds can also be used. The amino compound is used in an amount effec¬ tive to stabilize the virus. Generally, the concen¬ tration of the amino compound is 1-2 molar. The virus can be any virus or mixture of vi¬ ruses. Examples of such viruses include picorna- viruses, such as polio virus; rotavirus; respiratory syncytial virus; measles virus; and rubella. Gener¬ ally, the virus will be attenuated. For vaccines against poliomyelitis, the vaccine compositions can contain any or all of the various types of polio¬ virus. The preferred vaccines are the trivalent Sabin vaccines which contain types I, II and III of poliovirus. The vaccine compositions will typically be formulated at a pH ranging from about 6 to 8. Magnesium chloride, preferably 1 molar, can also be added to the compositions. Other immunogens such as diphtheria toxoid, tetanus toxoid and inactivated pertussis cells can combine with the viral components of the compo¬ sitions. In addition, the compositions can contain adjuvants which do not interfere with the activity of the stabilizing amino compound. The invention is illustrated further by the following exemplification. Although the stabilizing effects of the present invention are exemplified by a picornavirus, the present invention is useful to stabilize other viruses as well, including, but not limited to, those referred to above. Exemplification Methods and Materials Poliovirus (serotype 1, Mahoney strain) (PV1M) was grown in HeLa cells, purified on cesium chloride gradients and dialyzed against PBS, pH 7.2. Viral stocks contained approximately 4 x 10 11 PFU/ml and were stored at 4 °C. o Approximately 4 x 10 PFU were added to 1 ml of 5 mM phosphate buffer, pH 7.0, alone or containing 1 M L-lysine, D-lysine, L-arginine, glycine, L- alanine, N-a-acetyl-L-lysine, N-e-acetyl-L-lysine, L-lysine methyl ester, ethylenediamine, 1,5- diaminopentane, ethylamine, poly(ethylenimine) , spermidine or MgCl . The pH of each solution was adjusted to 7.0 with HC1 prior to the addition of poliovirus. The resulting solutions were placed in 1.4 ml Eppendorf tubes, sealed and submerged in a water bath at 50 °C. Aliquots (10-100 ul) were removed periodically, diluted with PBS and the titer of infectious poliovirus was followed by plaque assay on HeLa cells. Results In the first experiment the ability of 1 M concentrations of L-amino acids and MgCl_, pH 7.0, to stabilize PVIM against heat inactivation at 50 °C was tested. Figure 1 demonstrates that lysine and arginine stabilize PVIM 2 to 4 times better than MgCl- at all time points, whereas, L-alanine and glycine provide 10 to 10,000 times less stabiliza¬ tion than MgCl_ during the same period. In con¬ trols, which contained 5 mM phosphate buffer alone at pH 7.0, more than eight orders of magnitude of viral infectivity were lost after 3 hours. Lysine concentrations fo 0.1 to 2 M were used to optimize PVIM stability. These data show that 0.3 M L-lysine or below provide little extra stabil¬ ity and that at 2 M lysine poliovirus stability is maximal. Figure 2 compares stabilization of PVIM by 1 and 2M L-lysine and MgCl_ at pH 7.0. These data show that L-lysine is 10 and 20 times better than MgCl- at stabilizing PVIM after 24 and 48 hours, respectively, at 50"C. Whether stabilization of PVIM by lysine is stereospecific was also assessed. To do this, L- and D-lysine were tested at 1M concentrations. These data demonstrate that both L- and D-lysine are equally effective in stabilizing PVIM against heat inactivation at 50°C (Table 1). TABLE 1 TABLE 1. The effect of 1 M L- and D-lysine stereo- so ers on the stabilization of poliovirus (serotype •a 1, Mahoney strain) against heat inactivation . Time hours Pla ue Formin Units Remainin a Poliovirus (approximately 4 X 108 PFU) was added to 1 ml of 5 mM phosphate buffer, pH 7.0 containing 1 M of the above compounds. The resulting solutions were placed in 1.4 ml Eppendorf tubes, sealed and submerged in a water bath at 50 °C. Aliquots were removed periodically, diluted with PBS and the titer of infectious poliovirus was followed by plaque assay on HeLa cells. b Values should be multiplied by 108 Since lysine has an a- and e-amino group which may be involved simultaneously in binding opposite charges on the capsid surface, the effect of a- or e-acetylated derivatives of L-lysine which lack the corresponding a- or e- NH_ group was tested. In addition, the effect of the carboxyl group of L- lysine was tested by using L-lysine methyl ester. These data demonstrate that L-lysine or its methyl ester were equally protective against heat inactiva- tion, whereas removal of either the a- or e-NH group from L-lysine abbrogated the ability of these compounds to stabilize PVIM (Table 2) . TABLE 2 TABLE 2. The effect of lysine modification on the stabilization of poliovirus (serotype l, Mahoney strain) against heat inactivation . Time (hours Plaque Forming Units Remaining at 50 °C) N-e-acetyl N-a-acetyl L-lysine lysine -L-lysine -L-lysine methyl ester 3.1 a Poliovirus (approximately 4 X 108 PFU) was added to 1 ml of 5 mM phosphate buffer, pH 7.0 containing 1 M of the above compounds. The resulting solutions were placed in 1.4 ml Eppendorf tubes, s- _ed and submerged in a water bath at 50 °C. Aliquots were ' removed periodically, diluted with PBS and the titer of infectious poliovirus was followed by plaque assay on HeLa cells. b Values should be multiplied by 108. c Values are below 100 PFU/ l. These data suggested that compounds other than lysine which contain 2 amino groups might be effec¬ tive stabilizers. Consequently, ethylenediamine, poly- (ethylenimine) , spermidine, 1-5 diaminopentane or ethylamine (a monoamine) were tested at 1 M concen¬ tration. These data show that ethylenediamine, 1-5 diaminopentane, poly(ethylenimine) are as effective, and spermidine is slightly less effective, than lysine at stabilizing PVIM, whereas ethylamine does not stabilize PVIM (Table 3). TABLE 3 TABLE 3. The effect of mono-, di- and polyamines on the stabilization of poliovirus (serotype 1, Mahoney strain) against heat inactivation a . Time Plaque Forming Units Remaining (hours at ethylene- poly(ethylen- eth^l sperm lysine 1,5-diamino- 50 °C) diamine -imine) -aιr,ine -idine pentane a Poliovirus (approximately 4 X 108 PFU) was added to 1 ml of 5 mM phosphate buffer, pH 7.0 containing 1 M of the above compounds. The resulting solutions were placed in 1.4 ml Eppendorf tubes, sealed and submerged in a water bath at 50 °C. Aliquots were removed periodically, diluted with PBS and the titer of infectious poliovirus was followed by plaque assay on HeLa cells. b Values should be multiplied by 108. Values are below 100 PFU/ml.

Claims: CLAIMS 1. A vaccine composition, comprising an aqueous solution containing a virus and a compound containing at least two amino groups in an amount sufficient to stabilize the virus. 2. A vaccine composition of Claim 1, wherein the virus comprises at least one type of attenuated poliovirus. 3. A vaccine composition of Claim 1, wherein the virus comprises attenuated types I, II and III of poliovirus. 4. A vaccine composition of Claim 1, wherein the amino-containing compound comprises two amino groups separated by a spacer group. 5. A vaccine composition of Claim 4, wherein the spacer group comprises a substituted or unsub- stituted alkyl group. 6. A composition of Claim 5, wherein the amino- containing compound is selected from the group consisting of diaminoethane, diaminopropane, diaminobutane, diaminopentane and spermidine. 7. A composition of Claim 1, wherein the amino- containing compound is a basic amino acid or a salt thereof. 8. A composition of Claim 7, wherein the amino acid is lysine or arginine. 9. A composition of Claim 1, wherein the amino containing compound is a polyamine. 10. A composition of Claim 9, wherein the polyamine is poly(ethylenimine) . 11. A composition of Claim 1, wherein the concen¬ tration of amino-containing compound is at least 1-2 molar. 12. A vaccine composition of Claim 1, further comprising magnesium chloride. 13. A vaccine composition for poliomyelitis, com¬ prising an aqueous solution of at least one type of attenuated poliovirus and a compound containing at least two primary amino groups in an amount sufficient to stabilize the polio¬ virus. 14. A vaccine composition of Claim 12, wherein the poliovirus comprises types I, II and III of poliovirus. 15. A vaccine composition of Claim 13, wherein the amino-containing compound is an amino acid or a salt thereof. 16. A composition of Claim 14, wherein the amino acid is lysine or arginine. 17. A vaccine composition for poliomyelitis, com¬ prising an aqueous solution of attenuated types 1 II and III of poliovirus and an amino acid, or salt thereof, containing two amino groups in a concentration of at least 1 molar. 18. A method of preparing a vaccine composition, comprising preparing an aqueous solution of a virus and a compound containing at least two amino groups in an amount sufficient to stabi¬ lize the virus. 19. A method of Claim 17, wherein the amino-con¬ taining compound is an amino acid or a salt thereof. 20. A method of Claim 18, wherein the concentration of amino-containing compound is at least 1 molar. 21. A method of preparing a vaccine composition for poliomyelitis, comprising preparing an aqueous solution of attenuated types I, II and III of poliovirus and an amino acid, or salt thereof, containing two amino groups in a concentration of at least about 1 molar. 22. A method of Claim 20, wherein the amino-con¬ taining compound is an amino acid or a salt thereof.

Inventors: CHOW MARIE, DORVAL BRENT, KLIBANOV ALEXANDER, CHOW, MARIE, DORVAL, BRENT, KLIBANOV, ALEXANDER
Applicants: MASSACHUSETTS INST TECHNOLOGY, MASSACHUSETTS INSTITUTE OF TECHNOLOGY
Application year: 1990
Main classification: A61K39
IPC codes: A61K9, A61K31, A61K39, A61K47