Activation of the human complement cascade by bacterial cell walls, peptidoglycans, water-soluble peptidoglycan components, and synthetic muramylpeptides--studies on active components and structural requirements

Cell walls isolated from 29 strains of 24 gram-positive bacterial species, whose peptidoglycans belong to the group A type of Schleifer and Kandler's classification, with one exception (Arthrobacter sp.), were shown to activate the complement cascade in pooled fresh human serum mainly through the alternative pathway and partly through the classical one. The complement-activating effect of cell walls (5 species) possessing group B type peptidoglycan, except those of Corynebacterium insidiosum, was weaker than that of the walls with group A type peptidoglycan. Preparations of peptidoglycan isolated from cell walls of Staphylococcus aureus, Streptococcus pyogenes, and Lactobacillus plantarum also activated the alternative pathway of the complement cascade, but less effectively than the respective parent cell walls. A water-soluble "polymer" of peptidoglycan subunits (SEPS), which was prepared from Staphylococcus epidermidis peptidoglycans by treatment with a cross-bridge degrading endopeptidase, retained most of the complement-activating ability of the parent cell walls. A peptidoglycan "monomer," SEPS-M, which was obtained by hydrolysis of the glycan chain of SEPS with endo-N-acetylmuramidase to disaccharide units did not activate complement. In conformity with this finding, neither synthetic N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) nor MDP-L-Lys-D-Ala activated the complement cascade. Among several lipophilic derivatives of MDP, 6-O-(3-hydroxy-3-docosylhexacosanoyl)-MDP-L-Lys-D-Ala (BH48-MDP-L-Lys-D-Ala) and 6-O-(2-tetradecylhexadecanoyl)-MDP (B30-MDP) were shown to activate complement through the alternative as well as the classical pathway and exclusively through the classical pathway, respectively. The finding that a D-isoasparagine analog of B30-MDP caused the same effect as the parent molecule strongly suggests that the activation of complement by B30-MDP is different from that caused by cell wall peptidoglycans and a water-soluble "polymer" of peptidoglycan subunits.

Mother-to-offspring transmission of human T cell leukemia virus type I in rabbits

We studied the mode of natural transmission of human T-cell leukemia virus type I (HTLV-I) in rabbits. Four virus-infected rabbits (2 males and 2 females) were individually mated with 4 noninfected rabbits. Two virus-infected females mated with noninfected males gave birth to 7 offspring, and 2 noninfected females mated with infected males delivered 5 offspring. Four of the seven offspring born to the virus-infected mothers seroconverted for HTLV-I when aged 6 to 13 weeks with antibody titers of 1:40 to 1:160. None of the five offspring born to the noninfected mothers became seropositive during the observation period of 6 months, however. Peripheral lymphocytes were cultured with T cell growth factor, and HTLV-I-carrying lymphoid cell lines were established from the four seroconverted rabbits. All four cell lines were of T cells positive for Ia antigens. In addition, none of five newborn rabbits killed immediately after birth to a virus-infected rabbit was infected with HTLV-I. These findings provide an experimental support for the milkborne transmission of HTLV-I from mother to child in humans and indicate that the virus is tropic for T cells in rabbits as well.

Chemical composition and immunobiological activities of sodium dodecyl sulphate extracts from the cell envelopes of Actinobacillus actinomycetemcomitans, Bacteroides gingivalis and Fusobacterium nucleatum

The chemical composition and immunobiological activities in vivo and in vitro of sodium dodecyl sulphate extracts (SDS-SE) derived from periodontopathic bacteria (three strains of Actinobacillus actinomycetemcomitans, two strains of Bacteroides gingivalis, and one strain of Fusobacterium nucleatum) were investigated. The main components of SDS-SE were protein and lipid, with negligible amounts of peptidoglycan and lipopolysaccharide. Immunopotentiating activity was detected in both delayed-type hypersensitivity and antibody formation against the elicitation of a protein antigen with the SDS-SE preparations of A. actinomycetemcomitans ATCC 29524 and B. gingivalis 381 and 1021. On the other hand the SDS-SE of A. actinomycetemcomitans ATCC 29522 enhanced only the induction of a delayed-type hypersensitivity response. All the SDS-SE preparations had mitogenic activity to splenocytes from BALB/c nu/nu, C3H/HeN and C3H/HeJ mice. Migration-stimulating activity for human peripheral blood monocytes was detected especially in the SDS-SE preparations of A. actinomycetemcomitans ATCC 29524 and Y4. All of the SDS-SE samples inhibited [3H]thymidine uptake in human gingival fibroblasts and caused degradation of the cells. The results suggest that the cell membrane components extractable with sodium dodecyl sulphate from periodontopathic bacteria are involved in the pathogenesis of periodontal disease.

Possible existence of a novel amphipathic immunostimulator in the phenol-water extracts of Mycobacteriaceae

The extracts having diverse immunostimulating activities were obtained as a water-phase fraction from four bacterial species representing the 4 genera (Mycobacterium, Nocardia, Gordona, and Rhodococcus) of Mycobacteriaceae by the phenol-water method, which is commonly used for extraction of endotoxic lipopolysaccharides (LPS) from gram-negative bacteria and amphipathic substances from gram-positives. These fractions, especially those of G. aurantiaca and R. terrae, showed strong stimulatory effects on murine splenocytes, macrophages of mice and guinea pigs, the immunoadjuvant activities in guinea pigs and mice, and the distinct activities inducing a tumor necrosis factor and interferons alpha/beta and gamma in primed mice. The fractions from G. aurantiaca and R. terrae exhibited potent pyrogenicity and the ability to activate the clotting enzyme cascade of the horseshoe crab (Tachypleus tridentatus). Some of these biological activities were not very different from the potency of the reference endotoxic LPS derived from Escherichia coli or Fusobacterium nucleatum. But the test fractions neither showed the activity to prepare rabbit skin to the local Shwartzman reaction, nor reacted with anti-lipid A conventional and monoclonal antibodies. Furthermore, unlike LPS, these fractions stimulated the splenocytes of C3H/HeJ mice (LPS-Nonresponder). Although the fractions showing the above biological activities have not yet been adequately purified, they contained polysaccharides, whose main constituent sugar is mannose with a smaller amount of arabinose, fatty acids consisting primarily of palmitic, stearic, and tuberculostearic acids, and small amounts of peptides and amino sugars. Since components characteristic of known immunomodulators of bacterial origin, namely endotoxins (lipid A's), cell wall peptidoglycans, lipoteichoic acids, cord factors (trehalose dimycolates), or deoxyribonucleic acids, were practically not detected in these fractions, the agent responsible for the above bioactivities is considered to be a novel substance different from the known, bacterial immunomodulators.

Limited chymotryptic digestion of bovine adrenal 190,000-Mr microtubule-associated protein and preparation of a 27,000-Mr fragment which stimulates microtubule assembly

A heat stable microtubule-associated protein of Mr 190,000 (190-kDa MAP) has been purified from bovine adrenal cortex (Murofushi, H., Kotani, S., Aizawa, H., Hisanaga, S., Hirokawa, N., and Sakai, H. (1986) J. Cell Biol. 103, 1911-1919). Limited chymotryptic digestion of 190-kDa MAP produced a fragment of Mr 27,000 (27-kDa fragment), which bound to microtubules reconstituted in the presence of taxol. This fragment was purified with the aid of cosedimentation with microtubules. The purified 27-kDa fragment showed an ability to stimulate tubulin polymerization in the absence of taxol. Electron microscopic observation of microtubules reconstituted from purified 27-kDa fragment and tubulin revealed that the microtubules were in the form of thick bundles and that lateral projections which can be seen in microtubules reconstituted from intact 190-kDa MAP and tubulin were not observed. These results indicate that 27-kDa fragment includes or is a part of microtubule-binding domain of 190-kDa MAP and that this fragment is active in stimulating microtubule assembly. Amino acid analysis revealed that the 27-kDa fragment was rich in lysine, proline, and alanine, the sum of these three being about 45% of the total amino acids and that the contents of methionine, tyrosine, phenylalanine, and histidine were very low. These data suggest that the microtubule binding domain of the 190-kDa MAP comprises an unique structure.

Corneal test as a reliable method for detection of the delayed-type hypersensitivity reaction in mice

Antigen solution could be injected into the cornea of sensitized mice using a fine needle and a stereoscopic dissecting microscope. The resulting corneal reaction was shown to be a reliable method in the detection and estimation of delayed-type hypersensitivity in mice that had been immunized with a water-in-oil emulsion containing an ovalbumin and a cell wall adjuvant. Unlike the delayed skin reaction in the ear lobe, this corneal reaction was not affected by a coexisting Arthus reaction.

Analgesic effects of N-acetylmuramyl-L-alanyl-D-isoglutamine in decreasing the acetic acid-induced abdominal-writhing response

A new pharmacological action of N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP) is described. Pretreatment of male ddY mice with MDP, but not its biologically inactive analogs, significantly decreased the frequency of acetic acid-induced writhing movements more effectively than did acetylsalicylic acid (aspirin). The analgesic effect of MDP, however, was less than that of a narcotic antagonist, pentazocine.

Identification of the 190 kD microtubule-associated protein in cultured fibroblasts and its association with interphase and mitotic microtubules

We previously investigated the biochemical characteristics of microtubule-associated proteins (MAPs) of the adrenal medulla and adrenal cortex and found that they contain a new kind of MAP with a molecular weight of 190,000 (190 kD MAP) as a major species (Kotani, S., H. Murofushi, S. Maekawa, C. Sato, and H. Sakai. Eur. J. Biochem. 156, 23-29, 1986). We now have used an affinity purified anti-(190 kD MAP) antibody and show by indirect immunofluorescent microscopy the association of this MAP with microtubules in situ in TIG-3 cells (human embryonic lung fibroblasts). The 190 kD MAP was present along the interphase and mitotic microtubules, and there was no marked difference between the staining pattern with anti-tubulin and that with anti-(190 kD MAP) antibodies, evidence that the localization of 190 kD MAP is not restricted to the subset of microtubules. We also isolated MAPs from TIG-3 cells and identified their 190 kD MAP as a major heat-stable component. Several other unidentified polypeptides were recovered in the MAP fraction specifically.

Requirement of a properly acylated beta(1-6)-D-glucosamine disaccharide bisphosphate structure for efficient manifestation of full endotoxic and associated bioactivities of lipid A

Several synthetic acylated glucosamine monophosphates, with structures corresponding to the nonreducing or reducing moiety of the lipid A of the Escherichia coli or Salmonella minnesota type, and a synthetic compound corresponding to a biosynthetic disaccharide lipid A precursor (designated Ia or IVA) were examined for their endotoxic and related bioactivities in comparison with those of the synthetic and bacterial parent molecules, i.e., acylated beta(1-6)-D-glucosamine disaccharide bisphosphates. Some of the test monosaccharide compounds were definitely active in most of the in vitro assays. Their activities, except for complement activation, however, were weaker than those of the reference compounds, synthetic and bacterial acylated disaccharide bisphosphates. The differences between the test monosaccharide and disaccharide compounds were much more apparent in in vivo assays, in which the test acylated glucosamine monophosphates were scarcely active, though some test compounds exhibited weak lethal toxicity in galactosamine-loaded mice and were weakly active in pyrogenicity, immunoadjuvant activity, and possible tumor necrosis factor and alpha and beta interferon-inducing ability in Mycobacterium bovis BCG- and Propionibacterium acnes-primed mice, respectively. Mixture at an equimolar ratio of acyl glucosamine monophosphates, each of which has the structure of the reducing or nonreducing moiety of the reference disaccharide compound, did not restore the endotoxic or associated bioactivities of the corresponding parent molecules. No essential differences in bioactivity were noted between synthetic and bacterial monosaccharide compounds, i.e., lipid X, whose structure corresponds to the reducing moiety of E. coli-type lipid A.

Immunobiological activities of synthetic lipid A analogs with low endotoxicity

Synthetic lipid A analogs, beta(1-6)glucosamine disaccharide 1,4'-bisphosphates, which possesses four tetradecanoyl groups at the 2- and 2'-amino, and 3- and 3'-hydroxyl groups (LA-17-PP), and each two of the (R)-3-hydroxytetradecanoyl and tetradecanoyl groups at the 2- and 2'-amino and 3- and 3'-hydroxyl groups, respectively (LA-18-PP), were far less endotoxic than synthetic (506, LA-15-PP) and bacterial Escherichia coli type lipid A's; neither compound showed any detectable lethal toxicity in chicken embryos or preparatory activity for the local Shwartzman reaction in rabbits. Also both compounds were only weakly pyrogenic and comparably less lethally toxic in galactosamine-loaded mice than the reference synthetic and bacterial lipid A's and a synthetic counterpart to biosynthetic lipid A precursor Ia (406, LA-14-PP). Nevertheless, LA-17-PP and LA-18-PP exhibited definite in vivo immunoadjuvant activity in mice, and the ability to induce a possible tumor necrosis factor and alpha/beta interferon in Mycobacterium bovis BCG and Propionibacterium acnes-primed mice, respectively, although these activities were weaker than those of the reference lipid A's. 4'-Monophosphate analogs of the above two test compounds exhibited neither endotoxic nor beneficial activities, but they showed remarkable in vitro bioactivities comparable to those of the corresponding bisphosphate compounds; the ability to activate the human complement system and the clotting enzyme cascade of horseshoe crab amoebocyte lysate, stimulatory effects on guinea pig and murine peritoneal macrophages, and murine splenocytes.

Purification and characterization of a 190-kD microtubule-associated protein from bovine adrenal cortex

A heat-stable microtubule-associated protein (MAP) with molecular weight of 190,000, termed 190-kD MAP, was purified from bovine adrenal cortex. This MAP showed the same level of ability to promote tubulin polymerization as did MAP2 and tau from mammalian brains. Relatively high amounts of 190-kD MAP could bind to microtubules reconstituted in the presence of taxol. At maximum 1 mol of 190-kD MAP could bind to 2.3 mol of tubulin. 190-kD MAP was phosphorylated by a cAMP-dependent protein kinase prepared from sea urchin spermatozoa and by protein kinase(s) present in the microtubule protein fraction prepared from mammalian brains. The maximal numbers of incorporated phosphate were approximately 0.2 and approximately 0.4 mol per mole of 190-kD MAP, respectively. These values were lower than that of MAP2, which could be heavily phosphorylated by the endogenous protein kinase(s) up to 5 mol per mole of MAP2 under the same assay condition. 190-kD MAP had no effects on the low-shear viscosity of actin and did not induce an increase in turbidity of the actin solution. It was also revealed that 190-kD MAP does not cosediment with actin filaments. These data clearly show that, distinct from MAP2 and tau, this MAP does not interact with actin. Electron microscopic observation of the rotary-shadowed images of 190-kD MAP showed the molecular shape to be a long, thin, flexible rod with a contour length of approximately 100 nm. Quick-freeze, deep-etch replicas of the microtubules reconstituted from 190-kD MAP and brain tubulin revealed many cross-bridges connecting microtubules with each other.

Chemical structure and biological activity relationship of bacterial cell walls and muramyl peptides

The biological activities of the cell walls of bacteria having different types of peptidoglycans, and those of stereoisomers and analogs of muramyl dipeptide (MDP), of N-acetylglucosaminyl-beta(1-4)-N-acetylmuramyl tetrapeptides having different L- and D-amino acids at the COOH-terminus, and of 6-O-acyl-MDPs were examined to elucidate the relationship between structure and activity. Replacement of the L-alanine residue of MDP with glycine and replacement of the D-isoglutamine residue with L-isoglutamine, L-glutamic acid, and D-isoasparagine, but not with D-glutamic acid, caused a marked decrease in the biological activities of the MDP molecule. Test disaccharide tetrapeptides, irrespective of the configuration of COOH-terminal amino acid, showed strong immunoadjuvant activity and stimulation of macrophages, whereas those having COOH-terminal L-amino acids exhibited greater pyrogenicity, induction of acute joint inflammation, and hemorrhagic necrosis at a primed site than those having COOH-terminal D-amino acids. Introduction of an alpha-branched higher fatty acid to the muramic acid residue resulted in the disappearance of pyrogenicity after i.v. injection, an increase of adjuvanticity, and a loss of dependence on administration vehicles. The lack of the immunopotentiating activity (adjuvanticity) in cell walls from group B-type bacterial species was explained by the combined inhibitory effects of the replacement of the L-alanine residue by glycine and involvement of the alpha-carboxyl group of the D-glutamic acid residue in linking with neighboring peptide subunits.

Oral transmission of human T-cell leukemia virus type I in the rabbit

Four female rabbits were given twice-weekly oral inoculation of 2-4 X 10(7) cells from a male rabbit lymphoid cell line persistently infected with human T-cell leukemia virus type I (HTLV-I). After 8 weeks, one of them was found to be seroconverted for HTLV-I. Peripheral lymphocytes from the 4 rabbits were cultured in the presence of T-cell growth factor, and a lymphoid cell line with a normal female karyotype was established only from the seroconverted rabbit. This cell line was reactive with a monoclonal antibody to rabbit T-cells and expressed HTLV-I antigens and virus particles.

Effectiveness of liposomes as potential carriers of vaccines: applications to cholera toxin and human malaria sporozoite antigen

Two antigens, cholera toxin (CT) and a synthetic albumin-conjugated 16-residue peptide derived from the circumsporozoite (CS) protein of Plasmodium falciparum sporozoites, were tested as immunogens in rabbits. The malaria peptide-albumin conjugate by itself was completely nonimmunogenic, and although cholera toxin was immunogenic it also expressed considerable native toxicity. After attachment of CT to liposomes containing ganglioside GM1, toxicity of CT was completely eliminated and antigenicity was enhanced. Therefore liposomes may be capable of reducing toxicity of certain potentially dangerous antigens such as toxins. After incorporation of the malaria peptide-albumin conjugate into liposomes a high titre of specific antibodies was induced against the malaria peptide but not against albumin. These antibodies also reacted with native CS protein. Three adjuvants, including lipid A and two types of lipophilic muramyl dipeptide, were compared and found to be effective in liposomes. Based on the conversion of synthetic P. falciparum CS peptide from a nonimmunogenic to an immunogenic form and on the 'toxoiding' effect of liposomes for CT, it is concluded that liposomes should be considered as being a useful carrier for antigens and adjuvants for vaccines for poorly antigenic or toxic substances.

Acute and chronic polyarthritis induced by an aqueous form of 6-O-acyl and N-acyl derivatives of N-acetylmuramyl-L-alanyl-D-isoglutamine in euthymic rats and athymic nude rats

The analogs of N-acetylmuramyl-L-alanyl-D-isoglutamine (MDP), 6-O-stearoyl-MDP (L18-MDP), and N-(N-acetylmuramyl-L-alanyl-D-isoglutaminyl)-N-stearoyl-L-lysine (MDP-Lys-L18) and N-(2-tetradecylhexadecanoyl)-MDP (B30-MDP) induced acute polyarthritis in both euthymic rats and in athymic nude rats after a single or multiple systemic administrations of their aqueous forms; water-in-oil emulsions did not induce acute polyarthritis. MDP and the adjuvant-active analogs MDP-O-nBu (MDP butyl ester), N-(3-hydroxy-2-docosylhexacosanoyl)-MDP (BH48-MDP) and the adjuvant-inactive analogs [L18-MDP (L)] or MDP-Lys-L18 (L), which is 6-O-stearoyl-N-acetylmuramyl-L-alanyl-L-isoglutamine, or N-(N-acetylmuramyl-L-alanyl-L-isoglutaminyl)-N-stearoyl-L-lysine, did not induce disease, at the dosages used. Histological examination of the acute exudative inflammatory reactions around joints revealed hypertrophy of both synovial villi and tendon sheath, infiltration of polymorphonuclear leukocytes (PMN) and fibrin deposition of the affected joint spaces. Most of these lesions rapidly subsided after cessation of the adjuvant injections. During multiple systemic injections of acyl-MDPs, this acute arthritis became chronic in euthymic rats but not in athymic nude rats; the chronic polyarthritis consisted of mononuclear cell infiltration and proliferation of the connective tissue growth and severe new bone formation of the shaft of the bone. It remains uncertain whether chronic polyarthritis results from the repeated flare of acute inflammatory reactions to the continuing stimulation of the adjuvants or whether it may require some immunologic process to such exogenous substances as bacterial fragments or autoantigens modified by exogenous substances such as type II collagen.

Adjuvant activity of 6-O-acyl-muramyldipeptides to enhance primary cellular and humoral immune responses in guinea pigs: adaptability to various vehicles and pyrogenicity

Thirteen 6-O-acyl-N-acetylmuramyl-L-alanyl-D-isoglutamines (6-O-acyl-MDPs), including four inactive D-isoasparagine and L-isoglutamine analogs, were tested for their pyrogenicity and immunopotentiating activity to stimulate primary humoral and cellular immune responses in guinea pigs to a model protein antigen, ovalbumin, when administered in various vehicles. Among them, derivatives whose muramic acid residue was substituted by alpha-branched (and beta-hydroxylated) higher fatty acids at the carbon-6 position, especially 6-O-(2-tetradecylhexadecanoyl)-MDP (B3O-MDP) and, to a lesser extent, 6-O-(3-hydroxy-2-docosylhexacosanoyl)-MDP (BH48-MDP) and its L-serine analog [BH48-MDP(L-Ser)], were found to exert strong adjuvant activity in both the induction of delayed-type hypersensitivity and the stimulation of circulating precipitating antibody levels when combined with nonirritating vehicles (liposomes, squalene-in-water emulsion, and phosphate-buffered saline). These vehicles did not efficiently support the adjuvant activity of MDP, the parent molecule of the above lipophilic derivatives. Pyrogenicity tests showed that introduction of alpha-branched higher fatty acid groups but not of straight, long-chain fatty acids at the 6-position of the muramic acid residue resulted in marked decrease of the pyrogenicity inherent to MDP via intravenous administration.

Adjuvant activity of 6-O-acyl-muramyldipeptides to enhance primary cellular and humoral immune responses in guinea pigs: dose-response and local reactions observed with selected compounds

6-O-(2-Tetradecylhexadecanoyl)-N-acetylmuramyl-L-alanyl-D-isoglutamine (B3O-MDP) and 6-O-(3-hydroxy-2-docosylhexacosanoyl)-MDP (BH48-MDP) were examined for immunopotentiating activity in stimulating the primary immune responses of guinea pigs to ovalbumin and for adverse reactions at the injection site and in the regional lymph nodes when administered in combination with several nonirritating vehicles. B30-MDP was found to potently stimulate both humoral and cellular immune responses, the latter by induction of delayed-type hypersensitivity, irrespective of the administration vehicle examined (liposomes, a squalene in water emulsion, Intralipid, phosphate-buffered saline, and Nikkol HCO-60 glucose solution), although the minimum effective dose was dependent on the vehicle used. Reactions in the footpad receiving the injection were negligible. Noticeable local reaction consisted of swelling of the lymph nodes in the region of the injection, but the swelling was only noted with higher doses and subsided 3 to 4 weeks after immunization, unlike the persistent swelling caused by the administration of water-in-mineral oil emulsions with or without B30-MDP. BH48-MDP and its L-serine analog, BH48-MDP(L-Ser), which has L-serine in place of L-alanine in MDP, in combination with the squalene-in-water emulsion, also intensely stimulated both cellular and humoral antiovalbumin immune responses, but the effects of these compounds seemed to be influenced to a greater degree by the vehicles than by B30-MDP. Thus, B30-MDP was chosen from a series of a 6-O-acyl derivatives of MDP as the most promising candidate for possible application in practical vaccines.

Muramyl dipeptide induces acute joint inflammation in the mouse

Acute joint inflammation was produced in BALB/c mice by a single intravenous injection of synthetic muramyl dipeptide (MDP), its stereoisomers and 6-O-acyl derivatives of MDP. Four adjuvant-active, but not five adjuvant-inactive MDP analogs induced acute swelling and erythema of the ankles and wrists which were detected around 6-10 hr, reached the maximum severity by 18-24 hr and subsided by days 3 to 4 after injection. Introduction of the stearoyl group, but not the alpha-branched long chain fatty acid group into the C-9 hydroxyl group of MDP enhanced and prolonged the joint lesions compared with MDP.

Serial transmission of human T-cell leukemia virus type I by blood transfusion in rabbits and its prevention by use of X-irradiated stored blood

Human T-cell leukemia virus type I (HTLV-I) was serially transmitted for 5 passages from rabbit to rabbit by blood transfusion. The virus could be transmitted with 20 ml of whole blood or washed blood cell suspension (fresh or stored for 1-2 weeks at 4 degrees C) but not with cell-free plasma from seroconverted rabbits. Seroconversion occurred 2-4 weeks after blood transfusion and serum anti-HTLV-I titers ranged from 1:20 to 1:640 with the immunofluorescence assay. From transfusion recipients of the 1st to 4th passages, virus-producing cell lines were established by culturing lymphocytes in the presence of T-cell growth factor (TCGF). Three of the 4 cell lines became TCGF-independent after 2-12 months of continuous culture. Blood was transfused between rabbits of opposite sexes and the recipient origin of each cell line was determined by chromosome analysis. We also investigated the effect of X-irradiation (6,000 rad) on blood from seropositive rabbits. Seroconversion likewise occurred in rabbits transfused with blood that had been irradiated immediately before transfusion but not in rabbits transfused with blood that had been irradiated and stored for 1-2 weeks at 4 degrees C. Thus, our rabbit model shows that HTLV-I is serially transmissible by blood transfusion and that this can be prevented by irradiation of blood. The same procedure, therefore, may be useful for the prevention of transfusion-related transmission of HTLV-I in humans.

Prophage type of recombinants produced by cell fusion between various combinations of lysogenic or non-lysogenic substrains from two Staphylococcus aureus L-forms

Streptomycin (SM)- or erythromycin (EM)-resistant lysogenic and non-lysogenic substrains were produced from two Staphylococcus aureus L-form strains lysogenic for different prophages, namely, EMT-L (prophage alpha) and 209P (prophage beta). Cells of these L-form substrains were fused in various combinations using polyethylene glycol (PEG), and the frequency of recombinants selected as double resistance to both SM and EM and the prophage types of these recombinants were examined. In all the combinations, the frequency of recombinants was greater when the cells were treated with PEG than when they were not, and the difference was statistically significant (p less than 0.01) in 13 combinations. Combination between the lysogenic SM-resistant EMT-L substrain [EMT(Smr-alpha)] and lysogenic EM-resistant 209P-L substrain [209P(Emr-beta)] and the reverse combination, between 209P(Smr-beta) and EMT(Emr-alpha), resulted in a majority of recombinants harboring prophage beta. The former combination yielded recombinants that all held both prophage alpha and beta.