SK Strain Research Articles

Organic acid produced by lactic acid bacteria from bekasam as food biopreservatives

Bekasam is one of the Indonesian fish fermented products that contain lactic acid bacteria (LAB). Previous research has obtained four LAB strains which are considered as bacteriocin producers, have antibacterial activity against pathogenic bacteria from food. In addition to a bacteriocins, LAB produce another compounds, such as organic acids. This study aimed to determine the produced organic acids and their antibacterial activity during LAB growth against of Lactobacillus monocytogenes, Staphylococcus typhimurium, Escherichia coli, Bacillus cereus and Staphylococcus aureus, to determine the organic acid contents using HPLC and to identify LAB isolates using molecular method based on 16S rDNA sequences. The four LAB strains (BP (3), BP (20), BI (3) and SK (5)) were grown in MRS broth medium, then incubated at 37 °C for 48 hours and every 4 hours incubation was tested of titratable acid total (TAT), pH, LAB growth and antibacterial activity. The result showed that the exponential phase of bacteria growth occurred at 16-20 hours incubation and at the end of the exponential phase produced the highest antibacterial activity in the four LAB strains. The highest growth, TAT and antibacterial activity produced by the SK (5) strain. The highest organic acids content were lactic acid in the SK(5) strain and acetic acid in the BI(3) strain. Identification result indicated that BI(3), BP(3), and BP(20) strains were Pediococcus pentosaceus IE 3 with similarity of 98%, 97%, and 98%, respectively. While SK(5) strain showed 93% similarity to Lactobacillus plantarum subsp. plantarum NC 8. The four LAB strains produced organic acids and had antibacterial activity, so they can be developed as food biopreservatives.

Identification of critical residues for the activity and thermostability of Streptomyces sp. SK glucose isomerase

The role of residue 219 in the physicochemical properties of D-glucose isomerase from Streptomyces sp. SK strain (SKGI) was investigated by site-directed mutagenesis and structural studies. Mutants G219A, G219N, and G219F were generated and characterized. Comparative studies of their physicochemical properties with those of the wild-type enzyme highlighted that mutant G219A displayed increased specific activity and thermal stability compared to that of the wild-type enzyme, while for G219N and G219F, these properties were considerably decreased. A double mutant, SKGI F53L/G219A, displayed a higher optimal temperature and a higher catalytic efficiency than both the G219A mutant and the wild-type enzyme and showed a half-life time of about 150min at 85°C as compared to 50min for wild-type SKGI. Crystal structures of SKGI wild-type and G219A enzymes were solved to 1.73 and 2.15Å, respectively, and showed that the polypeptide chain folds into two structural domains. The larger domain consists of a (β/α)8 unit, and the smaller domain forms a loop of α helices. Detailed analyses of the three-dimensional structures highlighted minor but important changes in the active site region as compared to that of the wild-type enzyme leading to a displacement of both metal ions, and in particular that in site M2. The structural analyses moreover revealed how the substitution of G219 by an alanine plays a crucial role in improving the thermostability of the mutant enzyme.

Integrative Gene Cloning and Expression System for Streptomyces sp. US 24 and Streptomyces sp. TN 58 Bioactive Molecule Producing Strains

Streptomyces sp. US 24 and Streptomyces sp. TN 58, two strains producing interesting bioactive molecules, were successfully transformed using E. coli ET12567 (pUZ8002), as a conjugal donor, carrying the integrative plasmid pSET152. For the Streptomyces sp. US 24 strain, two copies of this plasmid were tandemly integrated in the chromosome, whereas for Streptomyces sp. TN 58, the integration was in single copy at the attB site. Plasmid pSET152 was inherited every time for all analysed Streptomyces sp. US 24 and Streptomyces sp. TN 58 exconjugants under nonselective conditions. The growth, morphological differentiation, and active molecules production of all studied pSET152 integrated exconjugants were identical to those of wild type strains. Consequently, conjugal transfer using pSET152 integration system is a suitable means of genes transfer and expression for both studied strains. To validate the above gene transfer system, the glucose isomerase gene (xylA) from Streptomyces sp. SK was expressed in strain Streptomyces sp. TN 58. Obtained results indicated that heterologous glucose isomerase could be expressed and folded effectively. Glucose isomerase activity of the constructed TN 58 recombinant strain is of about eighteenfold higher than that of the Streptomyces sp. SK strain. Such results are certainly of importance due to the potential use of improved strains in biotechnological process for the production of high-fructose syrup from starch.

Construction of new stable strain over-expressing the glucose isomerase of the Streptomyces sp. SK strain

In order to over express the xylA gene of Streptomyces sp. SK strain, it was cloned under the control of the constitutive ermE-up promoter. This construct was integrated through site-specific recombination process into the chromosome of a Streptomyces violaceoniger glucose isomerase deficient strain using the non-replicative vector pTS55. The resulting CBS4 strain shows a perfect stability in the absence of selection pressure. Its glucose isomerase activity was about four and nine-fold greater, than that obtained from Streptomyces sp. SK, respectively fully induced or not by xylose.

Glucose isomerase of the Streptomyces sp. SK strain: purification, sequence analysis and implication of alanine 103 residue in the enzyme thermostability and acidotolerance

The glucose isomerase gene (xylA) from the Streptomyces sp. SK strain encodes a 386-amino-acid protein (42.7 kDa) showing extensive identities with many other bacterial glucose isomerases. We have shown by gel filtration chromatography and SDS-PAGE analysis that the purified recombinant glucose isomerase (SKGI) is a 180 kDa tetramer of four 43 kDa subunits. Sequence inspection revealed that this protein, present some special characteristics like the abundance of hydrophobic residues and some original amino-acid substitutions, which distinguish SKGI from the other GIs previously reported. The presence of an Ala residue at position 103 in SKGI is especially remarkable, since the same amino-acid was found at the equivalent position in the extremely thermostable GIs from Thermus thermophilus and Thermotoga neapolitana; whereas a Gly was found in the majority of less thermostable GIs from Streptomyces. The Ala103Gly mutation, introduced in SKGI, significantly decreases the half-life time at 90 °C from 80 to 50 min and also shifts the optimum pH from 6.5 to 7.5. This confirms the implication of the Ala103 residue on SKGI thermostability and activity at low pH. A homology model of SKGI based on the SOGI (that of Streptomyces olivochromogenes) crystal structure has been constructed in order to understand the mutational effects on a molecular scale. Hence, the Ala103Gly mutation, affecting enzyme properties, is presumed to increase molecular flexibility and to destabilize, in particular at elevated temperature, the 91–109 loop that includes the important catalytic residue, Phe94.

A thermostable glucose isomerase having a relatively low optimum pH: study of activity and molecular cloning of the corresponding gene

A thermostable glucose isomerase from a newly isolated thermophilic Streptomyces sp. SK strain, had a wide pH range with an optimum of 6 at 60°C and 6.4 at 90°C. It was optimally active at 95°C and completely stable at 80°C for at least 5.5 h with a half-life of 5 h at 90°C. Using E.coli as a host strain and an internal fragment of xylA of S. olivochromogenes as a probe, a 6.5 kb DNA fragment from Streptomyces sp. SK was cloned. This fragment carries the entire xylA gene since the recombinant plasmid complements the E.coli xyl-5 mutant strain HB101. © Rapid Science Ltd. 1998

Multiplication of attenuated and virulent porcine parvoviruses in colostrum-deprived, neonatal pigs.

Colostrum-deprived, neonatal, 2 days old pigs were inoculated with the attenuated HT-/SK or the virulent 90HS strain of porcine parvovirus (PPV) by the oral or subcutaneous route and sacrificed 2, 4 or 6 days after inoculation. Then, comparison was made on viral multiplication in pigs between the two strains. Pigs inoculated with the HT-/SK strain showed no detectable viremia or HI antibody responses against PPV within 6 days after inoculation. Only in pigs inoculated by the subcutaneous route, a small amount of virus was recovered from the spleen, liver, or mesenteric lymph nodes. These viruses were distinguished from the parental virulent 90HS strain, as examined for rct maker in vitro. When pigs were inoculated with the virulent 90HS strain, viremia appeared in all of them 1 day after inoculation and continued for up to the sacrificed day. Moreover, a considerable amount of virus was also detected from all tissues, including brain, lung, liver, spleen, pancreas, small intestine, and lymph node tissues, in all pigs tested. HI antibodies were first detected 6 days after inoculation.

Establishment of the attenuated strain of porcine parvovirus for the live vaccine and its biological-immunological characteristics.

When the 90HS strain of procine parvovirus (PPV) was subjected to passages in embryonic swine kidney cell line (ESK cells), the low virulent HT- strain was obtained. When it was subjected continually to passages in primary swine kidney cultured (SK) cells at low temperature, attenuated HT-/SK strain as live virus vaccine was established. The ability of the HT-/SK strain to multiply in vitro was the highest at 32°C. The strain which multiplied at this temperature showed more than 3000 times as high an infective titer as that which multiplied at incubation of 37°C or 40°C. To examine the safety of the HT-/SK strain, 4-months-old piglets and pregnant sows negative for antibody were inoculated with this strain. No piglets or sows presented any abnormal clinical sign, viremia, or discharge of virus, or involved in contact infection. These swines showed complete ability of defense against challenge by intranasal inoculation with PPV of field strain. The pregnant sows immunized with the HT-/SK strain were challenged with PPV field strain to examine an effect of preventing fetal infection. They gave birth, however, to normal piglets, which were negative for serum antibody against PPV before sucking of colostrum. Therefore, no fetal infection was induced by high virulent field virus. On the other hand, abnormal young were born from a nonimmunized control sow. Virus was recovered from stillborn fetuses from this sow. Thus, it was considered that this strain could be used as attenuated live vaccine for prevention of PPV.

Trianthema portulacastrum — Local lesion host for brinjal mosaic and tobacco mosaic viruses

This paper deals with the first record of virus infections (brinjal mosaic virus and tobacco mosaic virus) on Trianthema portulacastrum L., a common weed in India. Trianthema portulacastrwn L., locally known as “Bishkhapra”, is a common weed with medicinal properties, and grows extensively in summer everywhere. It is a succulent, prostrate, glabrous or slightly pubescent herb with many branched, angular stems, leaves broader towards the tip, fruits small like flowers, concealed in the base of the leaf stalk. Experiments were carried out to determine the utility of T. portulacastrum as a local lesion host. The culture of mosaic disease of brinjal (Seth et al. 1967) and SK strain of tobacco mosaic virus (Verma et al. 1972) were maintained on Nicotiana glutinosa L. and N. tabacum cv. White Burley, respectively. The test plants of T. portulacastrum were raised in 4 inch pots, filled with sterilized soil, and kept inside the insect-proof glasshouse. For inoculations, the conventional method of macerating the infected leaf material in a mortar and pestle and rubbing the test seedlings by means of a cotton wool swab was employed. The plants were maintained on glasshouse benches at a temperature of 29 to 30°C. Within 6”7 days of inoculation, distinct countable chlorotic local lesions appeared which turned necrotic with a yellow halo over a period of 10”12 days. The lesions produced by both these viruses on T. portulacastrum were slightly different in their size and necrotic reaction on this host. Leaves of T. portulacastrum developed at first a few local lesions, followed by mosaic mottling of the newly emerging leaves in case of brinjal mosaic virus. Systemic infection, however, does not occur by tobacco mosaic virus in this host. A perusal of literature suggested that this constitutes the only record of a virus infection on Φ in India and is the first record as a local lesion host for brinjal mosaic virus and tobacco mosaic virus SK strain. Kristensen (1955) reported T. portulacastrum a systemic host of Beet yellows virus from Denmark. Die Mitteilung berichtet über Virusinfektionen (brinjal mosaic virus und Tabakmosaik-Virus) bei Trianthema portulacastrum , einem weitverbreiteten Unkraut in Indien.

Some factors influencing thermal stability of Mengo virus.

THERMAL inactivation of the Col SK strain of encephalomyocarditis virus has been studied by Bourdillon1. The rapid deterioration of several strains of encephalomyocarditis virus at high dilution in isotonic sodium chloride2–4 but stability in distilled water3,4 or concentrated sodium chloride4 has led to re-investigation of the thermal stability of the Mengo strain of encephalomyocarditis virus in several such ‘unphysiological’ diluents, using procedures described in a previous report4.

A MUTANT OF HERPES SIMPLEX VIRUS POSSESSING AN ATTENUATED PATHOGENICITY FOR BABY MICE OBTAINED BY EGG PASSAGE OF A NEWLY ISOLATED STRAIN

It has been attempted in this laboratory for the past years to isolate and passage herpes simplex virus by the chorioallantoic inoculation of embryonated eggs and pursue the changes in pathogenicities for various host animals occurring during the course of the passage. Among the pathogenicities examined were included those for baby mice intracerebrally or intraperitoneally inoculated, since Kilbourne and Horsfall (1951) stated that one-day old mice were equally susceptible to herpes virus inoculated by these two routes. A strain designated SK was studied most extensively.A fact came to light thereby that the SK strain after passaged through eggs about 50 times was hardly lethal to baby mice when given by the intraperitoneal route, whereas the classical HF strain experiencing more than 450 egg passages still possessed a high infectivity to baby mice even by the peripheral inoculation. This paradoxical result stimulated a quantitative analysis of the infectivities to baby mice of SK strain in comparison with HF strain, and it was eventually disclosed that a mutant had appeared incidentally in an early egg passage of SK strain, which subsequently had replaced the parent type virus after several more passages. Details of those experiments are reported in the present communication.

Investigations on neutralization and inhibition of hemagglutination by the parapoliomyelitis virus (Col SK strain) with sera from cases of encephalitis, aseptic meningitis and poliomyelitis

Es wird berichtet uber die Untersuchung einer Anzahl von Patienten mit der klinischen Diagnose Encephalitis, aseptischer Meningitis oder Poliomyelitis, sowie deren Kontaktpersonen, auf die Gegenwart neutralisierender und hamagglutinationshemmender Antikorper gegen Parapoliomyelitisvirus (Col SK-Stamm). Einwandfrei positive Ergebnisse mit beiden Untersuchungsmethoden betrugen bei einer Gruppe von insgesamt 23 Patienten 8,7% fur Neutralisation und 17,3% fur Hamagglutinationshemmung; bei einer Gruppe von insgesamt 30 klinisch gesunden Kontaktpersonen 16,7 fur Neutralisation und 0% fur Hamagglutinationshemmung. Die atiologische Bedeutung der serologischen Reaktionen fur die verschiedenen Krankheitsbilder wird diskutiert.

Myocarditis in poliomyelitis and related viral infections.

Editorial1 June 1951MYOCARDITIS IN POLIOMYELITIS AND RELATED VIRAL INFECTIONSP. W. C.P. W. C.Search for more papers by this authorAuthor, Article, and Disclosure Informationhttps://doi.org/10.7326/0003-4819-34-6-1502 SectionsAboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareFacebookTwitterLinkedInRedditEmail ExcerptClinical and epidemiological evidence indicates that poliomyelitis is a common, widespread infection which is usually restricted to the peripheral tissues and causes but little injury to the host. There is much indirect evidence that the gastrointestinal tract, including the pharyngeal mucosa, is both the portal of entry and primary locus of infection, and it is certainly the source from which the virus is disseminated. The involvement of the motor areas in the central nervous system, which causes the characteristic paralyses and has given the disease its name, is manifest only in a small proportion of the cases, and it is...1 SaphirWile OSA: Myocarditis in poliomyelitis, Am. J. M. Sc. 203: 781-788, 1942. CrossrefGoogle Scholar2 Saphir O: Visceral lesions in poliomyelitis, Am. J. Path. 21: 99-105, 1945. MedlineGoogle Scholar3 PealeLucchesi ARPF: Cardiac muscle in poliomyelitis, Am. J. Dis. Child. 65: 733-738, 1943. Google Scholar4 DolgopolCragan VBMD: Myocardial changes in poliomyelitis, Arch. Path. 46: 202-211, 1948. Google Scholar5 LuddenEdwards TEJE: Carditis in poliomyelitis. An anatomical study of 35 cases and review of the literature, Am. J. Path. 25: 357-373, 1949. MedlineGoogle Scholar6 Gefter WT: The heart in acute anterior poliomyelitis, Am. Heart J. 33: 228-239, 1947. CrossrefMedlineGoogle Scholar7 JungeblutSanders CWMJ: Studies of a murine strain of poliomyelitis virus in cotton rats and white mice, J. Exper. Med. 72: 407-436, 1940. CrossrefMedlineGoogle Scholar8 Jungeblut CW: Further experiments with Columbia Sk murine poliomyelitis virus, Bull. New York Acad. Med. 26: 571-577, 1950. MedlineGoogle Scholar9 RustigianPappenheimer RAM: Myositis in mice following intramuscular injection of viruses of the mouse encephalitis group and of certain other neurotropic viruses, J. Exper. Med. 89: 69-92, 1949. CrossrefMedlineGoogle Scholar10 Jungeblut CW: Newer knowledge on the pathogenesis of poliomyelitis, J. Pediat. 37: 109-128, 1950. CrossrefMedlineGoogle Scholar11 JungeblutSteenberg CWE: Neurotropic and viscerotropic strains of Columbia SK and encephalomyocarditis virus, Arch. Path. 49: 574-581, 1950. Google Scholar12 Editorial: Coxsackie viruses, Ann. Int. Med. 34: 257-263, 1951. LinkGoogle Scholar13 WarrenSmadelRuss JJESB: The family relationship of encephalomyocarditis, Columbia SK, MM. and Mengo viruses, J. Immunol. 62: 387-398, 1949. MedlineGoogle Scholar14 ToomeyTakacs JAWS: Experiments with the SK strain of poliomyelitis in smaller animals, J. Bact. 43: 87, 1942. Google Scholar15 MelnickWard JLR: Adaptation of poliomyelitis strains to rodents, with a word on nomenclature, Federation Proc. 7: 308, 1948. MedlineGoogle Scholar16 HelwigSchmidt FCEC: A filter-passing agent producing interstitial myocarditis in anthropoid apes and small animals, Science 102: 31-33, 1954. CrossrefGoogle Scholar17 DickSmithburnHaddow GWKCAJ: Mengo encephalomyelitis virus. Isolation and immunological properties, Brit. J. Exper. Path. 29: 547-558, 1948. Google Scholar18 SmadelWarren JEJ: The virus of encephalomyocarditis and its apparent causation of disease in man, J. Clin. Investigation 26: 1197, 1947 (abstract). MedlineGoogle Scholar19 Jungeblut CW: Neutralization of Columbia-SK and Yale-SK virus by polio-convalescent and normal human sera, Arch. Pediat. 67: 519-530, 1950. MedlineGoogle Scholar20 : A proposed provisional diagnosis of poliomyelitis virus, Science 108: 701-705, 1949. Google Scholar21 JungeblutStevens CWMA: Attempts to isolate poliomyelitis virus from the paralyzed muscle of patients during the acute stage of the disease, Am. J. Clin. Path. 20: 701-706, 1950. CrossrefMedlineGoogle Scholar22 Jungeblut CW: A preliminary note on the isolation of human poliomyelitis virus from the heart of fatal cases of the disease, Third European International Poliomyelitis Conference, Amsterdam, May 30-June 2, 1950. Google Scholar23 WardHorstmanMelnick RDMJL: The isolation of poliomyelitis virus from human extraneural sources. IV. Search for virus in the blood of patients, J. Clin. Investigation 25: 284-286, 1946. CrossrefGoogle Scholar24 Koprowski H: Isolation of poliomyelitis virus from human serum by direct inoculation into a laboratory mouse, Pub. Health Rep. 62: 1467-1476, 1947. CrossrefMedlineGoogle Scholar25 Melnick JL: Poliomyelitis virus in the blood stream in the experimental disease, Proc. Soc. Exper. Biol. and Med. 58: 14-16, 1945. CrossrefGoogle Scholar26 SommersWilsonHartman SCJCFW: Lymphoid lesions in poliomyelitis, J. Exper. Med. 93: 505-512, 1951. CrossrefMedlineGoogle Scholar This content is PDF only. To continue reading please click on the PDF icon. Author, Article, and Disclosure InformationAffiliations: PreviousarticleNextarticle Advertisement FiguresReferencesRelatedDetails Metrics Cited byGeneral histopathological aspects of some experimental viral encephalitidesAcute Aseptic Myocarditis and Meningoencephalitis in the Newborn Child Infected with Coxsackie Virus Group B, Type 3Significance of potassium depletion in poliomyelitisCurrent pediatric references 1 June 1951Volume 34, Issue 6Page: 1502-1508KeywordsCentral nervous systemGastrointestinal infectionsGastrointestinal tractMucous membranesMyocarditisParalysisPoliomyelitis ePublished: 1 December 2008 Issue Published: 1 June 1951 PDF downloadLoading ...

Influence of Pregnancy in Mice on the Course of Infection with Murine Poliomyelitis Virus

ConclusionsPregnant mice inoculated with the Col. SK strain of murine poliomyelitis virus by the oral route showed a definite increase in susceptibility to infection as compared with non-pregnant female control animals. Beginning with the 4th day of pregnancy, mortality increased progressively and reached, with the last 4 days of gestation, a rate almost twice that of the control group. Immediately after parturition there was a rapid return of resistance to the non-pregnant level. The mechanism responsible for the greater susceptibility of the pregnant mouse does not seem to depend wholly upon alterations in the permeability of the intestinal mucosa during gestation, since a smaller group of mice infected by the intravenous route exhibited a similar increase in susceptibility.

Evaluation of the Effect of Darvisul upon Infection with SK Strain of Virus in Mice.

Darvisul, N-(2-thiazolyl) -phenol sulfona-mide, or phenosulfazole was reported by Sanders, Subba Row, and Alexander1 to be effective against as many as 100 LD50 of a mouse virus, SK, when administration was begun 24 hours after intraperitoneal infection.

Infectivity of Murine SK Strain of Poliomyelitis Virus.

SummaryObservations are reported on the infectivity of the murine SK strain for mice based on certain types of exposure to the virus. Some of the infected mice were embedded in toto, sectioned, and examined histologically for evidence of virus multiplication in non-nervous as well as nervous tissue. Although infections occurred readily under various types of exposures to the virus, no lesions suggestive of virus activity were observed in any tissues or organs apart from the CNS. Infections by the intranasal route could not be prevented by prior intranasal instillations of zinc sulphate solution used to block the olfactory pathway as a portal of entry. Mice could be readily infected with virus-contaminated drinking water. Virus cultivated in developing eggs proved less infectious for mice when supplied to the animals in drinking water or food than mouse brain-cord virus suspensions. Old mice showed themselves less susceptible than young mice to certain types of exposure, but to other types of exposure the ...

Cultivation of the Murine SK Strain of Poliomyelitis Virus in Developing Eggs.

The murine SK strain of poliomyelitis virus was carried through 14 passages on developing eggs without evident diminution of virus content. Its multiplication was associated with a high incidence of deaths in the embryos. The incidence of deaths was influenced by the temperature at which the eggs were incubated after inoculation.

The Recovery of Poliomyelitis Virus from the Stools of Experimentally Infected Monkeys and Chimpanzees

Summary Following the inoculation of various strains of poliomyelitis virus into monkeys and chimpanzees by various parenteral routes, virus has been detected in the stools of seven primate species. Finding poliomyelitis virus in stools and intestinal contents in the monkey or chimpanzee is not sufficient evidence to point to the mouth as the portal of entry. The experiments do not indicate however whether the virus may be excreted first into the upper part of the alimentary tract and subsequently find its way to the intestines. In each of two chimpanzees a “healthy” carrier state lasting two and four weeks respectively developed following intracutaneous inoculation of the SK strain. A third chimpanzee that became a virus carrier had only slight transitory symptoms in the second week following inoculation. Virus appeared in the stools of some animals before any symptoms of the disease in the central nervous system were apparent.

Serologic Agglutination of Virus-Coated Bacterial Cells

Abstract In previous reports (1, 2) a technic was outlined by which certain neurotropic viruses (St. Louis Encephalitis and murine-adapted strain of Lansing Poliomyelitis) may be adsorbed to the surface of heat-killed bacterial cells (Serratia marcescens) and subsequently agglutinated by specific hyperimmune serum and by the convalescent serum of patients infected with the homologous virus. The test was designated as the Bacterial Agglutination (B.A.) Method for the detection of virus-related specific humoral factors. The validity of this reaction has been confirmed with experimental poliomyelitis (SK strain) in the monkey in which the initial appearance of this agglutinating factor in the blood stream was observed as early as the second day after inoculation (3). Weil (4) has confirmed the observation that viruses may be adsorbed by heat-killed bacterial cells and such cells specifically agglutinated by an antiserum homologous to the adsorbed virus.

STUDIES IN RODENT POLIOMYELITIS

1. Murine SK poliomyelitis virus has been transferred from mouse to guinea pig with the establishment of a fixed strain of cavian passage virus. 2. The disease thus produced in guinea pigs is characterized by the occurrence of flaccid paralysis. Typical poliomyelitic lesions are found in the anterior horn of the spinal cord. 3. Guinea pigs are susceptible to infection with murine virus by the intracerebral, intravenous, intraperitoneal, and subcutaneous route; cavian passage virus produces paralysis only upon intracerebral or intravenous injection. Neither virus paralyzes guinea pigs by feeding or nasal instillation. 4. The potency of the virus (murine or cavian) in guinea pigs is considerably lower than in mice and compares with the titer of the original SK strain in monkeys. In paralyzed guinea pigs the virus is found only in the central nervous system and not in extraneural sites, such as blood or abdominal viscera. 5. Attempts to cultivate cavian passage virus in tissue culture have yielded evidence of some in vitro propagation but no passage virus has as yet been obtained by this method. 6. Cross neutralization tests with cavian passage virus in guinea pigs and with murine virus in mice have established the serological identity of the two viruses. Inactivation of cavian passage virus in guinea pigs by poliomyelitis-convalescent monkey sera is irregular. Complete neutralization has been obtained with a concentrated poliomyelitis horse serum. 7. Resistance to reinfection with potent virus can be demonstrated in convalescent guinea pigs as well as in guinea pigs which have survived a symptomless infection with either murine or cavian virus. This immunity is demonstrable by the power of the serum of such animals to neutralize the virus in vitro and by the ability of nerve tissue to dispose in vivo of the infectious agent. 8. Cavian passage virus has a limited pathogenicity for rhesus monkeys. Of a total of 35 monkeys injected intracerebrally with guinea pig passage virus 26 failed to respond with any manifest symptoms of disease; 8 monkeys showed various signs of definite involvement of the central nervous system consisting of tremor, convulsions, facial palsy, and localized pareses; 1 monkey developed typical flaccid paralysis. 9. Following injection with cavian virus the virus may be recovered from the tissues of normal monkeys but not from the tissues of convalescent monkeys shortly after a paralyzing attack of poliomyelitis due to SK or Aycock virus. 10. Immunization of monkeys with early cavian passage virus by the subcutaneous route has given no clear-cut evidence of protection against intracerebral reinfection with SK poliomyelitis virus. Neither has there been any evidence of effective interference in monkeys injected intravenously with early cavian passage virus and intracerebrally with RMV poliomyelitis virus. 11. The bearing of the experimental data upon the epidemiology of the human disease is discussed.