Evidence of possible evasion of protective immunity by NAD-independent isolates of <i>Haemophilus paragallinarum<i/> in poultry

An indication of the ability of NAD-independent variants of Haemophilus paragallinarum to evade the immune system has been obtained from data obtained from several experiments. Firstly, it was noted that there was a difference in the serovar distribution between the NAD-dependent isolates in the 1990s and the NAD-independent isolates, as there was a significant decrease in the incidence of serogroup A NAD-dependent isolates. This can possibly be attributed to the extensive use of vaccines. On the other hand, most of the earlier NAD-independent isolates were serovar A. This is a possible indication of evasion of the protective immunity by the NAD-independent isolates. Further evidence of possible evasion of the protective immunity was obtained from results obtained when different isolates, both NAD dependent and NAD independent, were tested with a panel of monoclonal antibodies (Mabs). The V1 Mab reaction pattern was only seen in the reference strain 0083 among all of the NAD-dependent isolates tested in South Africa. This Mab was, however, found to react with some of the NAD-independent isolates. Furthermore, the isolation of NAD-dependent isolates in Australia which react with the V1 Mab also suggest possible evasion of the protective immunity by the NAD-independent isolates as no vaccines containing strain 0083 are used in Australia. In order to investigate the hypothesis of immune-evasion by NAD-independent H. paragallinarum, vaccinated and unvaccinated chickens were challenged with a NAD-independent serogroup C isolate. As a control, chickens were also challenged with NAD-dependent H. paragallinarum of the same serogroup. The results obtained indicate that there is no significant difference in the disease profiles obtained in vaccinated and unvaccinated chickens challenged with the NAD-independent isolate, thus providing further evidence of evasion of the productivity immunity by the NAD-independent isolates. The ability of the NAD-independent isolates to evade the immune system suggests that a different vaccination strategy, or alternative control methods may be needed for the control of IC caused by these isolates

On the Bragg, Leibfried, and Modified Leibfried Numbers

The Bragg, Leibfried, and modified Leibfried numbers are defined in the context of a theory of dislocation-mediated melting, and their values are determined from the properties of the dislocation ensemble at the melting temperature. The approximate numerical coincidence of the Bragg and modified Leibfried numbers is explained. The parameter K in the definition of the modified Leibfried number is shown to be the natural logarithm of the effective coordination number. Our analysis reveals that the Bragg number can be considered an elemental constant, in contrast to the Leibfried and modified Leibfried numbers.Comment: 5 pages, LaTe

Virulence of South African isolates of Haemophilus paragallinarum. Part 1: NAD-dependent field isolates

The virulence of four South African field isolates of NAD-dependent Haemophilus paragallinarum, representing the four serovars known to occur in that country, was investigated. During this study an alternative challenge model for infectious coryza was used, in which the infectivity as well the virulence of different isolates could be evaluated. The challenge model consisted of the direct challenge, via intrasinus injection of one chicken in a row of interconnected layer cages, containing 10 chickens, which are subsequently infected by natural routes. A scoring system of the clinical signs was established in which a score is given to the ability of the isolate to produce clinical signs in the challenge birds. The mean daily disease score for the flock can be calculated and plotted on a graph to give a graphic representation of the disease profile. A mean disease score, calculated over a 20-day examination period can be calculated. Isolates can then be compared to each other, either graphically or by a comparison of the mean disease scores. It has been demonstrated using this scoring system that the South African serogroup C isolates appear to be more virulent than the South African serogroup A or B isolates. It was further established that the serovar C-3 isolate appeared to be the most virulent.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.ICA Laboratories. ImmunoVet services. NRF.mn201

Virulence of South African isolates of Haemophilus paragallinarum. Part 2: Naturally occurring NAD-independent field isolates

Naturally occurring NAD-independent variants of Haemophilus paragallinarum, which have been isolates from poultry showing clinical signs of infectious coryza, were used to determine their virulence using a newly developed challenge model for infectious coryza. It was established that the NAD-independent isolates belonging to a particular serogroup, were less virulent when compared to the virulence of the NAD-dependent isolates from the same serogroup. It was shown that the virulence of the NAD-independent isolates belonging to serogroup C and serogroup A were very similar to each other. This differs to the results obtained with NAD-dependent isolates reported on previously, in which the serogroup C isolates were found to be more virulent then the serogroup A isolates.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.NRF. ImmunoVet Services.mn201

Health status of salmonids in river systems in Natal. I. Collection of fish and parasitological examination

A detailed microbiological and parasitological survey of salmonids and indigenous fish in the upper reaches of selected river systems in Natal was undertaken. Fish were collected from the rivers by electro-fishing, from dams by gill netting and from hatcheries along the rivers. A total of 678 fish from 26 different sites along 8 river systems were collected. No parasites could be detected on fish from four of the rivers tested. Parasites were, however, detected on fish from large production sites in Natal and in the rivers feeding these sites. Parasites which were detected were Ichthyopthirius multifiliis, various Trichodina spp., Apiosoma sp. and Gyrodactylus sp. The heads of all fish estimated to be less than one year of age were collected and examined for the spores of Myxosoma cerebralis. All of the samples were found to be free of this parasite.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

Health status of salmonids in river systems in Natal. II. Isolation and identification of viruses

A total of 678 fish from 26 different sites along 8 river systems was examined for the presence of trout viruses. No isolations of any viruses were made from any fish collected from these systems in Natal during this study. No antibodies against any of the trout viruses were detected in the serum collected from these fish. It would appear from this study that the river systems in Natal are free of any of the known viruses of trout. Infectious pancreatic necrosis virus was, however, isolated from trout from the Natal Parks Board Hatchery at Kamberg Nature Reserve on the Mooi River during June and July of 1988. Neutralising antibodies against the VR 299 serotype of lPN virus were detected in the serum collected from trout at Kamberg in September 1988.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.Directorate of Animal Health.mn201

The indirect fluorescent antibody technique for the rapid identification of streptococcosis of rainbow trout (Salmo gairdneri)

The indirect fluorescent antibody technique has been used successfully for the rapid serological identification of the Streptococcus sp. responsible for streptococcosis of rainbow trout. This technique has been used to identify the Streptococcus sp. in pure cultures and smears made from experimentally infected and diseased fish.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.lmchunu2014mn201

Health status of salmonids in river systems in Natal. III. Isolation and identification of bacteria

Both pathogenic and non-pathogenic bacteria were isolated from fish, both salmonid and non-salmonid, from selected river systems in Natal. Pasteurella pisicida was isolated for the first time from fish in South Africa. The isolation of Yersinia ruckeri, Aeromonas salmonicida, and Edwardsiella tarda were recorded for the first time from fish in Natal. A. hydrophila and Flexibacter columnaris were found to be widespread throughout the river systems in Natal. The Streptococcus species which caused serious disease problems in trout in the Cape Province and Transvaal was not isolated from any of the fish examined in Natal.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

Isolation of serovar C-3 Haemophilus paragallinarum from Zimbabwe: a further indication of the need for the production of vaccines against infectious coryza containing local isolates of H. paragallinarum

Various isolates of Haemophilus paragallinarum, collected from a severe outbreak of infectious coryza in poultry from Zimbabwe, were serotyped and were found to belong to serovar C-3. Previously, isolates were serotyped using polyclonal antiserum produced against serogroup reference strains (0083 for serogroup A, 0222 for serogroup B and Modesto, or H-18 for serogroup C) of H. paragallinarum. In this case, polyclonal antiserum produced against these reference isolates were used, as well as polyclonal antiserum that has been raised specifically against the serovar C-3 isolate 46 C-3. When using the latter serum at a 1 in 50 dilution, no cross-reaction with other members of serogroup C were found. The severity of the disease outbreak in Zimbabwe, the vaccination history of the infected flocks on the sites and the isolation of the uniquely southern African serovar C-3, further highlights the need for vaccines composed of local isolates to control infectious coryza in regions where vaccination failures occur.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat v.9 was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

The use of the GENETRAK Escherichia coli probe kit for the detection of three atypical E. coli isolates

A commercially available E. coli probe kit was used to test 1 lactose negative E. coli isolate and 2 hydrogen sulphide-producing E. coli isolates. The isolates were confirmed as E. coli by means of the API system. The GENETRAK E. coli DNA probe kit reacted positively with the lactose negative isolate, but negatively with the hydrogen sulphide-producing isolate.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201