Cross-protection Tests Research Articles

Immunogenicity of Haemophilus paragallinarum Serovar B Strains

Immunogenicity of three Haemophilus paragallinarum serovar B strains was investigated in cross-protection tests using monovalent vaccines prepared from the B strains, as well as one strain each of serovars A and C. A bivalent vaccine composed of the serovar A and C strains also was used. In the studies with the monovalent vaccines, the immunogenicity of serovar B strains was different from that of serovar A and C strains, although only partial serovar B-specific protection with the three strains was observed. Chickens vaccinated with the bivalent vaccine protected against challenge with one serovar B strain, as well as serovar A and C strains, but not against the other two serovar B strains.

Effectiveness of Cross Protection by a Mild Strain of Zucchini Yellow Mosaic Virus in Cucumber, Melon, and Squash

A mild variant of zucchini yellow mosaic virus (ZYMV-WK) that had been selected from a severe strain of ZYMV in France was used for cross-protection tests in cucurbit crops in Taiwan. Under greenhouse conditions, ZYMV-WK provided protection in cucumber, melon, and zucchini squash against four severe strains originally from Connecticut, Florida, France, and Taiwan. Cross protection was more effective against the French strain, from which the mild strain was derived. Two field trials with zucchini squash under moderate and high disease pressures showed that ZYMV-WK provided excellent cross protection against the Taiwan strain of ZYMV (.)

Hemagglutinating Activity and Immunological Properties of Haemophilus paragallinarum Field Isolates in Japan

Four field isolates (S4, S10, S15, and S17) of Haemophilus paragallinarum were recovered from chickens affected with infectious coryza in widely separated regions of Japan. Their hemagglutinating (HA) activity and immunological properties were compared with those of strain 221 of serovar A/1 and strains Modesto and S1 of serovar C/2. When treated with potassium thiocyanate or hyaluronidase, all the isolates showed HA activity against formaldehyde-fixed chicken erythrocytes but not against fresh chicken erythrocytes. In the hemagglutination-inhibition (HI) test, the isolates cross-reacted with strains Modesto and S1 but not with strain 221. The immunological properties of these isolates, as determined by cross-protection tests, were similar to those of strain S1 and, to a lesser degree, strain Modesto, but not to strain 221. Our results indicated that the four field isolates belong to serovar C/2 and that the HI test is a suitable method for serotyping H. paragallinarum.

Genetics of resistance to the African trypanosomes. VII. Trypanosome virulence is not linked to variable surface glycoprotein expression.

The question of linkage of virulence traits to variable surface glycoprotein (VSG) expression in African trypanosomiasis was addressed. Previously we demonstrated that daughter cells arising in mice infected with a genetically homogeneous trypanosome population of Trypanosoma brucei rhodesiense were more virulent than the infecting population (J. A. Inverso and J. M. Mansfield, J. Immunol. 130:412, 1983). These virulent trypanosomes expressed differences in surface phenotype compared with the infecting variant types, and we proposed that virulence may be "linked" to VSG expression. In the present study, however, we have shown that expression of virulence is independent of the VSG phenotype displayed by trypanosome populations. A VSG-identical but highly virulent subpopulation of T. b. rhodesiense LouTat 1 was derived by rapid subpassage and subcloning in immunosuppressed mice. The virulent LouTat 1A subclone derived in this manner killed B10.BR/SgSnJ mice in 3 to 4 days postinfection compared with approximately 60 days for the parent clone, LouTat 1. The virulent subclone LouTat 1A appears to express the same VSG as the less virulent LouTat 1 population, as determined by polyspecific and monoclonal antibody-binding assays, cross-protection tests, and amino acid sequence analyses of the N-terminal portion of the VSG molecules. When LouTat 1 and subclone LouTat 1A were injected into a heterologous host species, multiple variant antigenic types (VATs) arising from each inoculum were isolated and characterized. VATs derived from the virulent subclone were as uniformly virulent for B10.BR mice as LouTat 1A. In summary, these results demonstrate that trypanosome virulence, once expressed, is a stable phenotype that does not seem to be associated with a particular VSG phenotype, nor does virulence change with the expression of different VSG genes.

Characterisation of a monoclonal antibody capable of neutralising the haemorrhagic activity of West African Echis carinatus (carpet viper) venom

D. Iddon, M. Hommel and R.D.G. Theakston. Characterisation of a monoclonal antibody capable of neutralising the haemorrhagic activity of West African Echis carinatus (carpet viper) venom. Toxicon 26, 167 – 179, 1988. — A murine monoclonal antibody (SV-1/F10) was highly specific immunologically for West African E.carinatus venom both by ELISA and immunoblotting. In cross-protection tests in vivo, it possessed strong antihaemorrhagic activity. This IgGl monoclonal antibody recognised an epitope present in a protein band of 124,000 mol. wt using immunoblotting of non-reduced Nigerian and Ghanaian E.carinatus venoms, as well as in a second protein band of 105,000 mol. wt in Ghanaian E.carinatus venom. The SV-1/F10 monoclonal antibody is of potential use for the isolation of West African E.carinatus venom haemorrhagin from whole venom, allowing the possibility of elucidation of the mechanism of its actions as well as its interactions with antibody.

Comparative study of two strains of Bovid herpesvirus-4

Two strains of Bovid herepesvirus-4 (BHV-4), i.e. the prototype strain DN-599, obtained from a steer suffering of a respiratory disease, and the strain 85/BH 16TV, originated from a cow with vulvovaginitis, were compared in studies which included restriction endonuclease analysis, experimental infection and reciprocal cross protection tests. The restriction endonuclease analysis revealed that the resultant DNA patterns of the isolates were generally similar with only a difference in one fragment. The two strains were capable of causing respiratory tract infection in calves, even if they displayed a different level of virulence: the strain 85/BH 16TV being the most virulent while the strain DN-599 the least. The two viral strains were mutually protective in that the calves were generally found to be refractory to challenge inoculation with either the homologous or the heterologous virus. Finally, both viral strains failed to evoke the production of neutralizing antibody in the experimental calves.

Enteric redmouth disease: outbreak in rainbow trout in Switzerland

Enteric redmouth disease: outbreak in rainbow trout in Switzerland

Cross protection of mice against different rabies virus isolates

In an attempt to identify “atypical” strains which could account for vaccination failures, 10 street, one intermediate (DR19) and 4 fixed rabies virus isolates from men, cattle, dogs, cats, mongoose and vampire bats in five countries (Argentina, Brazil, Chile, Cuba, and France) were studied by cross-protection tests in mice. For the purpose of this study, any virus that killed more than 20 % of the vaccinated mice challenged with that virus was considered “atypical”. When the suckling mouse brain rabies vaccine was used, two “atypical” isolates were found: one, from a human case in Chile (91, 125 mouse passages) and the other, from a vampire bat in Brazil (DR19, 22 mouse passages). However, when mice immunized with a cell culture vaccine (PV-BHK) of a higher antigenic value than the brain vaccine, were challenged with those same isolates, mortality was below 20%. The fact that these two isolates killed enough vaccinated mice to be considered “atypical” could be related to antigenic differences between these viruses and those included in the vaccine. However, since this mortality was observed only in the mice immunized with the vaccine with a lower antigenic value, reasons are given why it could be attributed to other biological characteristics of those strains than antigenic differences. Causes for vaccines failures other than immunological differences of rabies virus strains are also analyzed and discussed.

Comparative studies of strains of infectious bovine rhinotracheitis virus isolated from latently infected calves

Three strains (479 C, 778 TL, 982 LE) of infectious bovine rhinotracheitis (IBR) virus isolated from latently infected calves were compared with the prototype strain of IBR virus (LA strain) in studies which included restriction endonuclease analysis, experimental infection, and reciprocal cross protection tests in cattle. From the restriction endonuclease analysis it appeared that the 3 “latent” viruses were derived from the same isolate, and that it differed slightly from the LA strain. However, latency does not seem to have affected the pathogenicity or the immunogenicity of the virus. This is demonstrated by the identical clinical and virologic response of calves subjected to experimental infection with the various strains under study, and by the finding that when the LA strain and a “latent” strain (982 LE) were tested in cross protection tests in cattle, they proved to be mutually protective.

Comparative study of rotavirus strains of bovine and rabbit origin

Newborn calves were susceptible to infection with a rotavirus strain isolated from rabbits and, conversely, rabbits 4–5 weeks of age became ill and some died when inoculated with the rotavirus strain of bovine origin. However, the latter isolate appeared to be more virulent than the rabbit isolate in either calves or rabbits. Moreover, in reciprocal cross protection tests, carried out in calves and in rabbits, the rabbit rotavirus antiserum afforded only weak protection to challenge infection with either the homologous or the heterologous virus. By contrast, the protective level of the bovine rotavirus antiserum was relatively high.

Experimental infection and cross protection tests in calves with cytopathic strains of bovine rotavirus

Four cytopathic strains (81/32F, 81/36F, 81/40F, 82/80F) of bovine rotavirus were shown to be pathogenic for conventionally reared newborn calves. Calves were infected orally, using 3 calves for each isolate. All became febrile, were depressed and diarrhoeic. Two calves, one of which in the group of those infected with 81/36F isolate, and the other infected with strain 81/40F, were killed when moribund. A 3rd calf from the 81/36F infected group, died. At necropsy localized lesions of the small intestines, which are considered to be typical of rotavirus infection, were found. Virus was consistently isolated from the fecal samples of the inoculated calves up to 13 days post-inoculation. It was speculated that some differences existed in the virulence of the bovine rotaviruses tested. The cross protection tests revealed that 1 strain (81/36F) might be antigenically more complex than the others.

Comparison of Ciliary Activity and Virus Recovery from Tracheas of Chickens and Humoral Immunity after Inoculation with Serotypes of Avian Infectious Bronchitis Virus

Cross-protection tests with homologous and heterologous serotypes of infectious bronchitis virus (IBV) were used to compare ciliary activity and virus recovery from tracheas of chickens. Validation of this technique included correlating the neutralization indices of antiserum obtained from some infected birds. Chickens were inoculated intratracheally with either the JMK or Connecticut (Conn) serotype of IBV. Three weeks later, infected and uninfected groups were challenged by the same route with homologous and heterologous virus. The JMK strain provided immunity against homologous challenge and the Conn strain, as indicated by good ciliary activity and lack of challenge virus recovery. The Conn strain provided only homologous protection, as ciliostasis occurred and virus was recovered after challenge with the JMK strain. In each case, antiserum to immunizing virus neutralized only the homologous virus. Controls were uniformly susceptible and lacked neutralizing antibody. A similar experiment with the Ark 99 serotype and a recent isolate (397) of IBV revealed complete cross-protection of the tracheas. Antiserum to each virus neutralized the homologous and heterologous virus in each case in reciprocal tests. The results indicate that these two viruses are closely related. The complete agreement between ciliary activity and virus isolation indicates that ciliary activity is a reliable, objective criterion upon which tracheal immunity can be judged in cross-protection tests.

Antigenic variants of rabies virus

The authors studied nineteen strett virus isolates from different regions of Canada using either anti-nucleocapsid and anti-glycoprotein monoclonal antibodies or cross-protection tests. This study only allowed us to recognize three groups of viruses with different nucleocapsid patterns, and no difference, as far as protection with a Pitmann-Moore vaccine is concerned, between four of these strains.

The ability of Mycoplasma mycoides subspecies mycoides and closely related strains from goats and sheep to immunize mice against subspecies capri.

Small colony (SC) strains of Mycoplasma mycoides subsp. mycoides from contagious bovine pleuropneumonia (CBPP) and from goats were compared with large colony (LC) strains of so-called M. mycoides subsp. mycoides from goats and sheep by means of a cross-protection test in which mice were challenged with M. mycoides subsp. capri. Of 13 LC strains, all gave partial cross-protection, and 11 were shown to be more closely related than four SC strains to subspecies capri. In a further experiment, six SC strains--three from CBPP and three from goats--all gave weak partial cross-protection against subspecies capri.

Further studies on caprine and ovine mycoplasmas related to Mycoplasma mycoides subsp. mycoides.

Nine caprine and ovine mycoplasma strains, said to be indistinguishable serologically from Mycoplasma mycoides subsp. mycoides (the causative organism of contagious bovine pleuropneumonia; CBPP) were examined in mice by (1) a mycoplasmaemia test, and (2) a cross-protection test. Of the nine strains, two from goats belonged to a small colony (SC) type; four caprine and three ovine strains belonged to a large colony (LC) type.The two SC strains - like a single SC strain examined in an earlier study - were indistinguishable from genuine M. mycoides subsp. mycoides as isolated from CBPP. They produced mycoplasmaemia readily. In a cross-protection test, the two SC strains and a CBPP strain immunized completely against each other.Of the seven LC strains, six - like six LC strains examined in an earlier study - were easily distinguished from genuine M. mycoides subsp. mycoides; except for one that was not tested, all were shown to lack the ability to produce mycoplasmaemia readily. In cross-protection tests all six strains immunized partially but not completely against a CBPP strain.The seventh LC strain (Mankefår 2833) was exceptional: it produced mycoplasmaemia readily, resembling the SC strains in this respect. Like other LC strains, in cross-protection tests it protected only partially against a CBPP strain. Strain Mankefår 2833 was isolated in ca. 1965 by Brack from a Barbary sheep (Ammotragus lervia) in a German zoo.The ability of Mankefår 2833 to produce mycoplasmaemia enabled it to be used as a challenge strain in cross-protection tests. For the purpose of such tests the collection of nine mycoplasma strains referred to above was augmented with six LC strains from an earlier study. Partial but not complete protection against Mankefår 2833 was produced by two caprine SC strains, one CBPP strain, and nine LC strains. Three further LC strains gave protection that may have been as strong as that produced by the homologous strain, but confirmatory experiments are needed. A strain of M. mycoides subsp. capri gave no protection against Mankefår 2833.

The effects of temperature and light on the symptom expression and viroid concentration in tomato of a severe strain of potato spindle tuber viroid

Indexing on tomato of dilution series prepared from young tomato seedlings infected with a severe strain of potato spindle tuber viroid (originally isolated from wild tuber-bearingSolanum and later used for cross-protection tests to detect mild strains) indicated that viroid concentration rose more quickly in tomato at 31°C than at 23°C at various light intensities. At either temperature, low light intensity for 17–18 hours each day did not critically limit synthesis. At 31°C, symptoms which were otherwise severe by 2 weeks were delayed and less obvious under low light. At 23°C, symptoms were delayed at low or higher light intensity and did not appear if the temperature was allowed to fall to 15°C at night. Leaf vein necrosis which was favoured by moderate rather than by high temperature, possibly was similar to necrosis induced by viruses or other infection.

Differentiation ofMycoplasma mycoidessubsp.mycoidesfrom certain closely related caprine mycoplasmas by mycoplasmaemia and cross-protection tests in mice

In recent years, mycoplasma taxonomists have found that numerous mycoplasma strains from goats are serologically indistinguishable from Mycoplasma mycoides subsp. mycoides, the causative agent of contagious bovine pleuropneumonia (CBPP), by routinely used tests, e.g. the metabolism- and growth-inhibition tests. As a result, such organisms are now openly referred to as M. mycoides subsp. mycoides. Seven of these so-called M. mycoides subsp. mycoides strains from goats were compared with two strains of M. mycoides subsp. mycoides from CBPP, and with one strain of M. mycoides subsp. capri, by means of two in-vivo tests, namely, (1) a test of the ability of each strain, injected intraperitoneally into mice, to produce mycoplasmaemia, and (2) a cross-protection test in mice. Of the seven strains, only one ('O goat') was indistinguishable from genuine M. mycoides subsp. mycoides; it also had small colonies resembling those of genuine M. mycoides subsp. mycoides. The other six were easily distinguished from genuine M. mycoides subsp. mycoides, and they produced large colonies. These six strains and others like them should no longer be given a name that fails to distinguish them from the causative agent of CBPP. Cross-protection tests showed that the seven goat strains referred to above differed from M. mycoides subsp. capri.

Cross protection among four viroids

Cross-protection tests were performed on tomato and/or chrysanthemum plants with a severe strain (PS) of potato spindle tuber viroid (PSTV), a mild strain of PSTV (PM), citrus exocortis viroid (CEV), chrysanthemum stunt viroid (CSV), and chrysanthemum chlorotic mottle viroid (ChCMV). The identities of all viroids used, except ChCMV, were confirmed by fingerprinting the purified 125I-labeled RNAs. On tomato plants, PS and CEV caused identical, severe symptoms; PM caused mild symptoms; CSV replicated without causing symptoms; and replication of ChCMV could not be detected. Each viroid produced distinctive symptoms on chrysanthemum plants. On tomato, PM protected against the expression of symptoms by PS and CEV. On chrysanthemum, CSV, PM, and PS protected against CEV, but ChCMV did not protect against PS, CEV, or CSV; and PS failed to protect against ChCMV. In two cases of cross-protection, bioassays indicated that both the protecting and the challenge viroids had replicated. Thus, despite their different fingerprints (and hence RNA sequences), CEV, CSV, and two strains of PSTV affect a common biological process not affected by ChCMV.

Superinfection by strains of tobacco streak virus

Eight selected strains of tobacco streak virus varied in their reactions in cross-protection tests. Of the 28 possible pairs of strains, eight reciprocally protected tobacco against each other, eight unilaterally protected, and with 12 pairs, neither member protected against the other. When infected tobacco was susceptible to superinfection it was less susceptible than healthy tobacco except with two of the strains, which reduced susceptibility very little. Susceptibility to other viruses was retained, however. The capacity of strain WC to superinfect was not increased by selection. Nonsuperinfecting strains added to superinfecting inoculum decreased lesion numbers. Top particles seemed not to function in superinfection. The determinant for superinfection was carried in bottom particles in heterologous mixtures. Recombination of superinfecting capacity and lesion type occurred upon superinfection with heterologous mixtures of middle and bottom particles.

Studies on avian infectious bronchitis virus in New Zealand

SummaryTwelve New Zealand isolates of avian Infectious Bronchitis virus were typed by the serum-neutralization test. Both the constant serum decreasing virus and the constant virus decreasing serum methods were used. Cross-protection tests in specific-pathogen-free chickens were also carried out.Four groups of viruses, designated serotypes A, B, C and D were distinguished by both methods. Immunization with B, C and D gave some protection to challenge with type A.