Risk factors for rectal lymphogranuloma venereum in gay men: results of a multicentre case-control study in the U.K.

OBJECTIVE: To identify risk factors for rectal lymphogranuloma venereum (rLGV) in men who have sex with men (MSM). DESIGN: A case-control study at 6 U.K. hospitals compared MSM with rLGV (cases) with rLGV-negative controls: MSM without potential rLGV symptoms (CGa) and separately, MSM with such symptoms (CGs). METHODS: Between 2008 and 2010, there were 90 rLGV cases, 74 CGa and 69 CGs recruited. Lifestyles and sexual behaviours in the previous 3 months were reported using internet-based computer-assisted self-interviews. Logistic regression was used to investigate factors associated with rLGV. RESULTS: Cases were significantly more likely to be HIV-positive (89%) compared with CGa (46%) and CGs (64%). Independent behavioural risks for rLGV were: unprotected receptive anal intercourse (adjusted OR (AOR)10.7, 95% CI 3.5 to 32.8), fisting another (AOR=6.7, CI 1.8 to 25.3), sex under the influence of gamma-hydroxybutyrate (AOR=3.1, CI 1.3 to 7.4) and anonymous sexual contacts (AOR=2.7, CI 1.2 to 6.3), compared with CGa; unprotected insertive anal intercourse (AOR=4.7, CI 2.0 to 10.9) and rectal douching (AOR=2.9 CI 1.3 to 6.6), compared with CGs. An incubation period from exposure to symptoms of 30 days was indicated. CONCLUSIONS: Unprotected receptive anal intercourse is a key risk factor for rectal LGV with the likelihood that rectal-to-rectal transmission is facilitated where insertive anal sex also occurs. The association between HIV and rLGV appears linked to HIV-positive men seeking unprotected sex with others with the same HIV status, sexual and drug interests. Such men should be targeted for frequent STI screening and interventions to minimise associated risks.

Clinical predictors of rectal lymphogranuloma venereum infection: results from a multicentre case-control study in the U.K.

OBJECTIVE: Since 2003, over 2000 cases of lymphogranuloma venereum (LGV) have been diagnosed in the U.K. in men who have sex with men (MSM). Most cases present with proctitis, but there are limited data on how to differentiate clinically between LGV and other pathology. We analysed the clinical presentations of rectal LGV in MSM to identify clinical characteristics predictive of LGV proctitis and produced a clinical prediction model. DESIGN: A prospective multicentre case-control study was conducted at six U.K. hospitals from 2008 to 2010. Cases of rectal LGV were compared with controls with rectal symptoms but without LGV. METHODS: Data from 98 LGV cases and 81 controls were collected from patients and clinicians using computer-assisted self-interviews and clinical report forms. Univariate and multivariate logistic regression was used to compare symptoms and signs. Clinical prediction models for LGV were compared using receiver operating curves. RESULTS: Tenesmus, constipation, anal discharge and weight loss were significantly more common in cases than controls. In multivariate analysis, tenesmus and constipation alone were suggestive of LGV (OR 2.98, 95% CI 0.99 to 8.98 and 2.87, 95% CI 1.01 to 8.15, respectively) and that tenesmus alone or in combination with constipation was a significant predictor of LGV (OR 6.97, 95% CI 2.71 to 17.92). The best clinical prediction was having one or more of tenesmus, constipation and exudate on proctoscopy, with a sensitivity of 77% and specificity of 65%. CONCLUSIONS: This study indicates that tenesmus alone or in combination with constipation makes a diagnosis of LGV in MSM presenting with rectal symptoms more likely.

Optimal number of samples to test for institutional respiratory infection outbreaks in Ontario.

The objective of this study was to determine the optimal number of respiratory samples per outbreak to be tested for institutional respiratory outbreaks in Ontario. We reviewed respiratory samples tested for respiratory viruses by multiplex PCR as part of outbreak investigations. We documented outbreaks that were positive for any respiratory viruses and for influenza alone. At least one virus was detected in 1454 (85∙2%) outbreaks. The ability to detect influenza or any respiratory virus increased as the number of samples tested increased. When analysed by chronological order of when samples were received at the laboratory, percent positivity of outbreaks testing positive for any respiratory virus including influenza increased with the number of samples tested up to the ninth sample, with minimal benefit beyond the fourth sample tested. Testing up to four respiratory samples per outbreak was sufficient to detect viral organisms and resulted in significant savings for outbreak investigations.

To what extent does Neisseria gonorrhoeae multiantigen sequence typing of gonococcal isolates support information derived from patient interviews?

Gonococcal isolates from genitourinary (GU) medicine clinic attendees in Glasgow, Scotland were typed using Neisseria gonorrhoeae multiantigen sequence typing (NG-MAST). Correlation between named partners (contacts) and NG-MAST type was sought and associations between specific NG-MAST types, and the social, epidemiological and geographical data were explored. We found NG-MAST typing to be a supportive and confirmatory tool for contact tracing. Specific NG-MAST types were found to be associated with distinct characteristics such as sexuality or chlamydial co-infection. An increased number of gonococcal infections were reported from those resident in deprived areas of Glasgow than from those resident in more affluent areas. However, there was no clear geographic clustering of specific NG-MAST types found within the city. Routinely observing the spread of common strains of gonorrhoea is likely best done from a larger geographical perspective unless a specific outbreak occurs.

A new Nigerian hunter snail species related to Enneaserrata d'Ailly, 1896 (Gastropoda, Pulmonata, Streptaxidae) with notes on the West African species attributed to Parennea Pilsbry, 1919.

Enneanigeriensis sp. n. is described from southeastern Nigeria on the basis of external and internal shell morphology. Following Pilsbry's formal criteria of a single palatal fold and corresponding external furrow, the new species may be assigned to Parennea. Enneanigeriensis sp. n. exhibits substantial similarity with E.serrata, a species from Cameroon, in the cylindrical shell shape, crenulate suture, and internal shell morphology, indicating that the two species are closely related. CT scanning confirmed the presence of only a single palatal fold in E.nigeriensis sp. n. and two in E.serrata. In spite of this, the Nigerian species is provisionally assigned to Ennea rather than Parennea, suggesting that the characters used to define Ennea and Parennea are insufficient to delimit natural groups of species. The holotype of E.serrata is examined for the first time since its description in 1896 and a redescription of the species is provided based on the two shells hitherto known. Study of the original specimens recorded as Ptychotrema (Parennea) sulciferum by Degner from Liberia reveals these to belong to Enneacf.thompsonae. The Nigerian shell recorded by van Bruggen as Ptychotrema (Parennea) aequatoriale proved to be a specimen of Enneacf.perforata. As a result, no species attributable to Parennea now appear to be known in West Africa; in contrast, numerous species are known from central and eastern Africa.

Boundaries of telomere conversion in Trypanosoma brucei.

Active genes for variant-specific surface glycoproteins (VSGs) reside in telomeric expression sites and may be replaced by other VSG genes via telomere conversions. The availability of a complete map of expression site 221 in variant 221a made it possible to determine the boundaries of such conversions and the sequences that are involved. We have analysed five trypanosome populations that arose from variant 221a through replacement of the 221 gene by another VSG gene. In each of these relapsed populations the telomere conversion ends at a different position in the expression site. In the relapsed population, 221aR3, the boundary was found in the coding region of an expression-site-associated gene (ESAG). This ESAG-2 codes for a potential 368-aa protein of unknown function; it contains a N-terminal signal peptide for mediating transfer to the endoplasmic reticulum and six potential N-glycosylation sites. It shares these structural features with the ESAG-1 protein encoded in the same expression site. ESAG-2 is a member of a large gene family which includes non-functional genes. In 221aR3, the partial conversion of ESAG-2 by an ESAG-2-like sequence has disrupted the open reading frame. The two ESAG-2 sequences are similar (92% identity) suggesting that sequence homology between telomeres provides the opportunity for gene conversion.

BALB/c mice infected with Brucella abortus express protracted polyclonal responses of both IgG2a and IgG3 isotypes.

A polyclonal IgG2a response dependent on the secretion of endogenous IFN-gamma has been demonstrated in BALB/c mice injected with killed whole cells of Brucella abortus [1]. Here we report intense and protracted polyclonal responses of IgG2a and also of IgG3 isotypes in BALB/c mice undergoing primary infections with B. abortus attenuated vaccine strain 19 or virulent strain 2308. Ratios of total serum Ig levels between infected mice and age matched controls were greater than 38 for IgG3 and greater than 12 for IgG2a between weeks 4 and 8 post-infection. Polyclonal increases of IgM and IgG1 that were proportionally much lower (ratios < 2 and < or = 3, respectively) also occurred in infected mice during this time. It is hypothesized that both IgG3 and IgG2a polyclonal responses required IFN-gamma, which was induced by B. abortus primarily in a T cell-independent fashion during the first weeks of infection, and from T cells thereafter.

Effect of pregnancy on the immune response of cattle to a Brucella vaccine.

An experiment was performed to determine whether humoral- or cell-mediated immune responses of cattle to a Brucella abortus vaccine were influenced by the stage of gestation. Heifers were vaccinated 2 mth before and 2 mth after breeding with cell envelopes of B. abortus in an oil adjuvant containing trehalose dimycolate and muramyl dipeptide. Control groups received adjuvant alone or no vaccine. Following breeding, vaccinated animals were divided into pregnant and nonpregnant subgroups. Immune responses to two outer membrane proteins were measured at monthly intervals by ELISA and lymphocyte blastogenesis tests. Skin tests were performed during the ninth month of gestation. Vaccination induced sustained immune responses, but few differences were detected between pregnant and non-pregnant animals. The relative increase in IgA antibodies to group 3 protein in nonpregnant heifers exceeded that in pregnant heifers during months 4 and 6 of gestation (P less than 0.05). Dermal hypersensitivity, measured by changes in double skin thickness, was significantly greater in nonpregnant heifers to porin (P less than 0.01) and group 3 (P less than 0.05) antigens at 24 h post-injection, but no significant differences in skin thicknesses or in the nature of the lesions were observed at 48 h. Animals which received adjuvant alone demonstrated negligible responses. Pregnancy had no significant effect on the responses of lymphocytes to phytohemagglutinin (PHA) or Concanavalin A (Con A). However, plasmas from nonvaccinated pregnant heifers taken during the sixth and seventh (but not eight or ninth) months of pregnancy decreased responses of normal donor cells to PHA and Con A when compared with those in autologous plasma (P less than 0.05).

Ototoxicity resulting from intracochlear perfusion of Streptococcus pneumoniae in the guinea pig is modified by cefotaxime or amoxycillin pretreatment.

Acute changes in the electrophysiology and ultrastructure of the organ of Corti were studied after microperfusion of c. 5 x 10(6) CFU of serotype 2 Streptococcus pneumoniae D39 or Escherichia coli K-12 directly into the scala tympani of guinea pigs. Hearing loss was assessed by recording the auditory nerve compound action potential response to a 10 kHz tone pip. Mean hearing loss 3 h after pneumococcal perfusion (n = 4) was 44 dB, compared to 6 dB after E. coli perfusion (n = 4) (P<0.001). After pneumococcal perfusion, scanning electron microscopy revealed damage to hair cell stereocilia and cratering of the apical surface of supporting cells. Intraperitoneal injection of 100 mg/kg cefotaxime (n = 4) or 100 mg/kg amoxycillin (n = 4) 30 min before perfusion of pneumococci significantly reduced mean hearing loss to 23 dB (P=0.01) or 20 dB (P=0.01), respectively, and diminished ultrastructural damage. The data suggest that if pneumococci invade the inner ear during meningitis, cochlear deafness may rapidly ensue.

Comparative immune responses to native cell envelope antigens and the hot sodium dodecyl sulfate insoluble fraction (PG) of Brucella abortus in cattle and mice.

Brucella abortus vaccines composed of native cell envelopes or outer membrane proteins of smooth strain 2308 were compared with a vaccine (PG) composed of the insoluble residue of strain 2308 cell envelopes which had been extracted with hot sodium dodecyl sulfate. Vaccines were given by injection in an oil base adjuvant containing trehalose dimycolate and muramyl dipeptide or without adjuvant. Mice vaccinated with 30 micrograms native cell envelopes or PG and challenged 4 weeks later with virulent B. abortus strain 2308 displayed equivalent levels of protective immunity at 1 and 4 weeks post-infection. Heifers were vaccinated with 5 mg of antigens in adjuvant; PG was also administered without adjuvant. Humoral and cell mediated immune (CMI) responses were tested at monthly intervals. PG without adjuvant induced negligible immune responses. Native cell envelope antigens induced significantly higher titers of whole cell agglutinins over a 3-month period than did PG, although revaccination with PG in adjuvant enhanced the production of agglutinins and both vaccines induced antibodies to the O polysaccharide. Lymphocyte blastogenesis responses and delayed hypersensitivity reactions to porin and group 3 proteins were stimulated by both native and PG vaccines, and the magnitude of the responses did not differ significantly between the treatment groups. These vaccines were therefore comparable in their capacity to induce protective immunity in mice and CMI responses in cattle, whereas antibody responses induced by PG in cattle were generally lower. These findings provide a basis for evaluation of nonliving B. abortus vaccines in cattle.

Cell titration assay for measuring blastogenesis of bovine lymphocytes.

The blastogenic response of bovine peripheral blood lymphocytes to phytohemagglutinin (PHA) and to microbial antigens was measured using a lymphocyte titration assay. Culture conditions, including lymphocyte concentrations, incubation periods and medium formulation, were established which produced linear or nearly linear responses over a range of cell concentrations. These conditions were established by testing lymphocytes from unimmunized cattle and from heifers infected with Brucella abortus with PHA and a B. abortus extract. Four cell concentrations in 2-fold increments were selected for measuring responses to PHA (3.125 X 10(3) to 2.5 X 10(4) cells/well) and to antigens (5.0 X 10(4) to 4.0 X 10(5) cells/well). The strength of response varied among animals and also over time for individual animals, but the titration assay allowed exponential proliferation to be distinguished from decline, which may have been due to overcrowding of microtiter wells, exhaustion of nutrients or induction of regulatory events. This assay provided a more reliable and discriminating method of evaluating lymphocyte proliferation responses than that achieved by single point assays. The displacement of the titration curves could be used to estimate the relative frequency of lymphocytes responding to antigens or mitogens.

Immune response of cattle to Brucella abortus outer membrane proteins measured by lymphocyte blastogenesis.

Lymphocytes from cattle were tested in a blastogenesis test with outer membrane proteins isolated from smooth strain 2308 and rough strain 45/20 of Brucella abortus. The titration assay developed for measuring blastogenesis to microbial antigens (Baldwin, Antczak and Winter, this issue, pp. 319-333) was used to assess the response to both group 2 (porins) (Douglas et al., 1984) and group 3 proteins (Verstreate et al., 1982). Blastogenesis was evaluated for distinguishing cattle infected with virulent B. abortus strain 2308 from unimmunized cattle, cattle vaccinated with attenuated strain 19, or inoculated with Escherichia coli 0116:H31, known to cause serological cross-reactions with B. abortus (Nielsen et al., 1980). Strain 45/20 porin was the most effective for this purpose and data analyses utilizing the titration assay were better than those relying on a single point assay. When compared with BASA, an antigen preparation used in other studies (Kaneene et al., 1978a), responses to porin provided a more specific index of infection with B. abortus. Reactions to 45/20 porin occurred, however, in some heifers vaccinated as adults with strain 19 or inoculated with E. coli 0116:H31. Furthermore, nonpregnant heifers had negligible or only transient blastogenesis responses to the porin during the first 14 weeks after infection even though they developed strong 0 antibody responses. We do not recommend the blastogenesis test in its present form as a useful adjunct to serological tests, and could allow measurement of cell mediated immune responses relevant to protective immunity.

Comparative histopathology in BALB/c mice infected with virulent and attenuated strains of Brucella abortus.

The course of infection in BALB/c mice of virulent Brucella abortus strain 2308 (S-2308) and attenuated strain 19 (S-19) varies markedly. Whereas S-19 is eliminated at an exponential rate beginning at 2 weeks post infection (p.i.), strain 2308 assumes a steady state or plateau during the first 6 weeks p.i. and thereafter is eliminated very slowly over a period exceeding 6 months. Here we compared the initiation and maintenance of inflammatory reactions in spleens and livers of mice infected with either of the two strains of B. abortus for the first 6 weeks p.i. Histological changes in the liver were similar in response to either strain and were characterized by the development of small granulomas and an influx of polymorphonuclear leukocytes (PMN) and monocytes. Tissue reactions in the spleen were similar at weeks 1 and 2 p.i. At 3 weeks p.i. and thereafter, focal granulomatous responses in S-2308-infected mice exceeded those in mice infected with S-19. Numbers of nonspecific esterase (NSE) positive mononuclear leukocytes in S-19-infected spleens had increased by 3 weeks p.i. and remained elevated. No comparable increase in NSE positive cells occurred in mice infected with S-2308, and numbers were significantly lower. At 4 weeks p.i. the influx of mature neutrophils and the intensity of extramedullary hematopoiesis were significantly greater in S-19-infected spleens. A profound depletion of periarteriolar lymphoid tissue was noted in both infections for the first 3 weeks p.i. However, repopulation of lymphoid sheaths in S-19-infected spleens became significantly greater by 4 weeks p.i. and continued to increase at significantly higher levels during the next 2 weeks. This study demonstrates quantitative differences in splenic inflammatory responses which are temporally related to the more rapid elimination of S-19. Based upon the lower susceptibility of strain 2308 to the protective effects of immune serum it is hypothesized that the different patterns of infection and inflammation displayed by the 2 strains may related to the differential capacities of antibody opsonized S-19 and S-2308 to survive in activated macrophages.

Evaluation of whole cell and subcellular vaccines against Brucella ovis in rams.

Five antigen preparations from Brucella ovis strain REO 198 were incorporated with the pluronic polymer L-121 and muramyl dipeptide and tested as vaccines against B. ovis infection of rams. The antigenic preparations were: (1) a fraction enriched in outer membrane proteins and rough lipopolysaccharide (hot saline extract, HS); (2) the proteins from HS substantially free of lipopolysaccharide; (3) outer membrane blebs; (4) outer membrane-peptidoglycan complexes extracted with detergent; (5) killed whole cells. The experimental vaccines were compared with two standard vaccines, rough Brucella abortus 45/20 whole killed cells in an oil based adjuvant, and live Brucella melitensis Rev 1. Immunizations with non-living vaccines were performed on two occasions, 18 weeks apart. The rams were challenged with a virulent strain of B. ovis 31 weeks after the second vaccination and slaughtered 15 weeks thereafter. Rates of infection in groups vaccinated with Rev 1 (33%), and HS (40%) were significantly lower (P < 0.005 and P < 0.025, respectively) than that in the non-vaccinated control group (87%). Strain 45/20 was the only other vaccine that conferred a significant level of protection (50%) (P < 0.05). The organ distribution of the infection and the level of colonization of infected organs did not differ significantly between infected animals in the various vaccine groups and those in the unvaccinated control group. No statistically significant relationship was detected between the magnitude of the antibody responses to the HS extract, to outer membrane proteins, or to the rough lipopolysaccharide, and freedom from infection. The results indicate that the HS extract of B. ovis may represent a useful alternative to B. melitensis Rev 1 or B. abortus 45/20 as a vaccine against B. ovis.

Ultrastructural damage to the organ of corti during acute experimental Escherichia coli and pneumococcal meningitis in guinea pigs.

Experimental meningitis was induced in 16 pigmented guinea pigs by subarachnoid inoculation of mid log-phase 1 x 10(9) E. coli K-12 (n = 8) or 5 x 10(7) Streptococcus pneumoniae type 2 (n = 8). Animals were killed at various times between 3 and 12 h after inoculation and the ultrastructure of the organ of Corti (including the basilar membrane) was examined with high resolution scanning electron microscopy. Both E. coli and S. pneumoniae induced meningitis and invaded scala tympani. In both types of meningitis the apical surface of inner supporting cells developed craters. inner hair cell stereocilia were also disrupted. In pneumococcal meningitis both these lesions were more pronounced but in addition there were breaks in the junctions between inner hair cells and their adjacent supporting cells and there was ballooning and rupture of the apical surface of outer hair cells. Damage to the organ of Corti after bacterial invasion of the inner ear may be one of the mechanisms by which bacterial meningitis can cause deafness. The more severe cochlear lesions induced by S.pneumoniae may explain the higher incidence of deafness after pneumococcal meningitis.

Antibody-producing cells in bovine lacteal secretions after local immunization.

The indirect Jerne plaque assay was used to determine the presence of antibody-forming cells in lacteal secretions of 2 cows inoculated in the mammary gland with T4 phage. Two adjacent mammary glands of 2 nonlactating 7-months pregnant cows were inoculated by intramammary injection 4 times at 3- to 5-day intervals. The presence of plaque-forming cells (PFC) was assessed in each quarter beginning on postinoculation day 8 and at 4- to 14-day intervals thereafter. Amounts of antibodies in serum and secretions were measured by an indirect hemagglutination test. The PFC were detected in secretions from all quarters of both cows between postinoculation days 8 and 32. Concentrations of PFC fluctuated within quarters during the course of the experiment but no relationship was evident between numbers of PFC in a quarter and its inoculation status. The use of monospecific antiglobulin sera at 1 sample-collection period revealed that cells synthesizing immunoglobulin (Ig)G and IgA antibodies were predominant in lacteal secretions. Antibody amounts in serum and secretions rose after inoculation, and titers in secretions were markedly higher in most instances. Antibody-forming cells were thus demonstrated to accumulate in the mammary gland after intramammary inoculation. The presence of antibody-forming cells in non-inoculated glands may have been the result of antigen transfer among quarters, but was considered more likely to have resulted from systemic migration of antigen-stimulated cells with migration into all quarters, regardless of inoculation status. Antibodies in lacteal secretions may have accumulated through a combination of local synthesis and selective transport from the bloodstream.

Bovine venereal vibriosis: activity of inflammatory cells in protective immunity.

The capability of bovine polymorphonuclear (PMN) and mononuclear phagocytes to kill Campylobacter (Vibrio) fetus venerealis was tested under various conditions in order to judge their roles in protective immunity. Bovine PMN killed C fetus in the presence of immunoglobulin G (IgG) but not immunoglobulin A (IgA) antibodies. Some phagocytosis occurred in the absence of antibody in glass-adherent cultures, but not in suspension cultures--indicating that surface phagocytosis by the neutrophils normally present during estrus could account for natural protection at this time. Mononuclear phagocytes also killed C fetus in the presence of opsonins, making this a likely factor in protection during the later stages of inflammation when mononuclear cells predominate. The presence of numerous lymphocytes in this mononuclear infiltration and the capability of C fetus antigens to induce delayed hypersensitivity (DH) are consistent with the possibility that cell-mediated immunity (CMI) also may be involved in protective immunity.

Decreased motility of bull spermatozoa caused by Mycoplasma bovigenitalium.

Mycoplasma bovigenitalium mixed with bull semen in egg yolk-citrate buffer and held at 5 C caused a highly significant time- and dose-dependent depression in sperm motility. Mycoplasma adhered to a majority of spermatozoa, principally to the acrosome, but also the the midpiece and tail. This may reflect the basis for a naturally observed condition in young bulls in which genital mycoplasmosis is associated with low sperm motility.

Effects of gamma radiation and azathioprine on Brucella abortus infection in BALB/c mice.

Sublethal irradiation of BALB/c mice 4 hours prior to inoculation with 5 x 10(4) virulent Brucella abortus, caused significant (P less than 0.01) reductions in bacterial numbers in comparison with numbers in unirradiated controls. Numbers of brucellae in the spleen were significantly lower by 5 days after inoculation and decreased thereafter, so that at 2 and 3 weeks after inoculation, there were up to 1,000-fold fewer organisms in the spleen of irradiated mice. The number of brucellae in the spleen increased in irradiated mice thereafter. The course of events in the liver was similar, but developed more slowly, and peak differences in bacterial numbers were about 1 log less. These phenomena were not attributable to differences in implantation of brucellae in the liver or spleen, nor to an abnormal distribution of organisms in other organs of irradiated mice. Irradiation of mice during the plateau phase of infection also resulted in significant (P less than 0.05) reductions in bacterial counts in the spleen during the succeeding 4 weeks. Macrophage activation in the spleen, measured by a Listeria monocytogenes-killing assay, was significantly (P less than 0.01) increased by irradiation alone at 1 week after inoculation and at that time was significantly (P less than 0.01) greater in B abortus-infected, irradiated mice than in B abortus-infected controls. Histologic, cytologic, and immunologic studies revealed that the decrease in numbers of organisms between 1 and 2 weeks after inoculation in irradiated mice occurred at a time when their immune response to B abortus was suppressed and when numbers of neutrophils and monocytes infiltrating the spleen were significantly (P less than 0.01) diminished.(ABSTRACT TRUNCATED AT 250 WORDS)

Protection of BALB/c mice against homologous and heterologous species of Brucella by rough strain vaccines derived from Brucella melitensis and Brucella suis biovar 4.

OBJECTIVE: To evaluate stable rough mutants derived from Brucella melitensis 16M and B suis 2579 (biovar 4) as vaccines against homologous and heterologous Brucella spp in the BALB/c mouse model. DESIGN, ANIMALS, AND PROCEDURE: Rough mutants VTRM1 and VTRS1 were obtained from B melitensis 16M and B suis 2579, respectively, by allelic exchange of rfbU gene encoding mannosyltransferase with a Tn5-disrupted rfbU gene. Mice were vaccinated with VTRM1 or VTRS1 and challenge exposed 8 weeks later. RESULTS: VTRM1 and VTRS1 replicated extensively in the spleen during the first 3 weeks of infection, then decreased rapidly. Antibodies specific for the O polysaccharide were not detected in sera of mice inoculated with either rough strain. Vaccination with VTRM1 or VTRS1 induced protection against virulent strains of B abortus (2308), B melitensis (16M), B suis biovar 1 (750), and B suis biovar 4 (2579). VTRM1 also protected against B ovis (PA) and against 4 field isolates of B abortus from bison or elk. VTRS1 conferred protection against 4 field isolates of B suis biovar 4 from reindeer. Vaccines prepared from live VTRM1 or VTRS1 provided significantly greater protection than that afforded by vaccines of killed cells in QS-21 adjuvant. Vaccination with VTRM1 containing VTRS1 gave minimal protection against the antigenically unrelated Listeria monocytogenes, thus demonstrating the immunologic specificity of protection against Brucella spp. CONCLUSIONS AND CLINICAL RELEVANCE: Results encourage evaluation, in primary host species, of VTRM1 and VTRS1, along with RB51, as alternative vaccines to strain 19, Rev 1, or other smooth phase vaccines.