Evaluation of a commercial quail pox vaccine (Bio-Pox Q) for the control of "variant" fowl poxvirus infections.

Groups of 3-week-old specific pathogen-free chickens immunized with a commercial live-virus quail pox vaccine (Bio-Pox Q) were not protected against challenge with "variant" poxviruses isolated from chickens that were previously vaccinated with commercial fowl pox vaccine. The percentages of vaccinated chickens resistant to challenge with each of the five variant field isolates were 0%, 20%, 0%, 20%, and 10%, respectively. However, when immunity engendered by the variant field isolates was challenged with the commercial quail pox vaccine virus, 80%, 70%, 80%, 50%, and 60% of the vaccinates, respectively, were protected. Results from cross-immunity studies indicate that the commercial quail pox vaccine does share some immunologic relationship with these variant poxvirus field isolates, but not enough to be used in the control of some outbreaks of pox caused by variant poxviruses.

Evaluation of a commercial modified live virus fowl pox vaccine for the control of "variant" fowl poxvirus infections.

Three-week-old specific-pathogen-free chickens were vaccinated with either a commercial modified live virus fowl pox vaccine or five "variant" poxvirus field isolates. Immunity engendered by the commercial modified vaccine or field isolates was challenged with either the variant isolates or commercial modified vaccine virus. The commercial modified vaccine did not adequately protect vaccinates against challenge with the variant isolates. The percentages of vaccinated chickens protected following challenge with each of the variant isolates were 70%, 20%, 30%, 20%, and 25%. However, when the isolates were applied as vaccines, 100% of the vaccinates were protected against challenge from the modified vaccine virus. Furthermore, the variant poxvirus isolates offered excellent protection from challenge with homologous variant isolates. The modified live virus vaccine was expected to offer significant protection against challenge from the variant pox isolates, but in this experiment it did not. The variant isolates tested may be good vaccine candidates to prevent the vaccine breaks currently encountered in previously pox-vaccinated flocks.

Dual infection of chickens with pox and infectious laryngotracheitis (ILT) confirmed with specific pox and ILT DNA dot-blot hybridization assays.

Dual infection with fowl pox (FP) and infectious laryngotracheitis (ILT) was diagnosed as the cause of acute mortality in a flock of three age groups of Hy-Line leghorn layers. The affected chickens had not been previously vaccinated against either FP or ILT. The diagnosis was confirmed by virus isolation, histopathology, and the use of specific pox and ILT genomic DNA probes in a dot-blot hybridization assay. FP and ILT vaccinations were recommended to control mortality. The use of FP- and ILT-specific DNA dot-blot hybridization may be used as a routine diagnostic tool to differentiate between the two diseases, especially in atypical cases of either infection or to confirm the existence of the two diseases as a mixed infection in a flock of chickens.

Effect of temperature on the stability of avian influenza virus antigens under different storage conditions.

The combined effect of time and temperature on the stability of two avian influenza virus (AIV) isolates concentrated with polyethylene glycol (PEG), stored at different temperatures, and used in the preparation of avian influenza vaccine was evaluated in turkeys at 24 hr and at 12, 24, 30, 36, and 42 months of storage. The differences detected between antibodies raised in turkeys by vaccines made from isolates under different storage conditions, times, and temperatures were not significant (P > 0.05), especially with vaccines prepared from one isolate. Virus recovery rates following challenge studies of vaccinated birds were similar. However, birds that were vaccinated twice had lower rates of virus recovery from the trachea, lungs, pancreas, and fecal samples following challenge infection. The results suggest that if stable isolates of AIV can be identified, such isolates can be rapidly concentrated with PEG and stored at -20 C or -196 C for at least 42 months without any loss of potency in the vaccine prepared from these isolates. This would reduce the costs associated with vaccine storage and subsequent expiration dates.

Pathogenicity and immunological relationship of quail and mynah poxviruses to fowl and pigeon poxviruses.

Specified-pathogen-free chickens inoculated with either quail or mynah poxvirus developed severe cutaneous lesions. The reaction was microscopically characterized as severe proliferative dermatitis with formation of cytoplasmic inclusion bodies in epithelial cells. In cross-protection studies in chickens, quail and mynah poxviruses proved immunologically different from pigeon and fowl poxviruses. Quail pox and mynah poxviruses also proved unrelated. Protection against infection from quail or mynah poxvirus infection was attained only when the homologous virus was used as a vaccine.

Enhancement of antibody response of turkeys to trivalent avian influenza vaccine by positively charged liposomal avridine adjuvant.

Trivalent avian influenza (AIV) antigens (H4N8, H5N2 and H7N3), mixed with positively charged, negatively charged and neutral avridine-containing liposomes, and oil-emulsion were subcutaneously administered to 6-week-old turkeys. Charged liposomal avridine adjuvant, either positive or negative, produced a better antibody response than uncharged liposomal avridine or oil-emulsion adjuvants when used in a trivalent avian influenza vaccine. The antibody response to the different antigens was generally greater to the positively charged adjuvanted vaccine compared with the negatively or neutral charged or oil-emulsion adjuvanted vaccines and these differences were significant (P less than 0.05) with the three antigens. The results suggest that the positively charged liposomal avridine plays a significant role as adjuvant to the AIV antigens.

Efficacy of avridine and liposomes as adjuvants for avian influenza virus antigens in turkeys.

Four-week-old turkeys were vaccinated with H4N8, H5N2 and H7N3 inactivated avian influenza viruses (AIV) in one of the following adjuvants: avridine, positively charged liposomal avridine, liposomal avridine with covalent attachment to the AIV antigens and oil-emulsion; and without any adjuvant. Two vaccinations were given at a 4-week interval. Antibody concentrations in sera and in respiratory lavages were measured over a period of 8 weeks. The turkeys responded with high cumulative geometric mean HI titres to the H4N8, H5N2 and H7N3 components of the vaccines, while the cumulative geometric mean HI titres for the antigens without adjuvant were significantly (P < 0.05) lower. The most efficacious adjuvant, positively charged liposomal avridine, gave the highest local immune response as measured by total antibody specific to AIV in respiratory lavages. The difference in weight gains between vaccinated and non-vaccinated turkeys was significant (P<0.05). Virus isolations 2 weeks post-challenge decreased in vaccinated turkeys.

A broad-spectrum avian influenza subtype antigen for indirect enzyme-linked immunosorbent assay.

A broad-spectrum viral antigen for the detection of avian-influenza-virus-specific antibodies, using the indirect enzyme-linked immunosorbent assay (ELISA), was identified. Purified and disrupted antigens were used, which helped to increase the sensitivity of the assay. All of the antigens tested were able to detect antibodies to homologous and heterologous viruses to varying degrees. The H9N2 antigen was the best single antigen to use in the ELISA to screen for avian influenza virus antibodies. It detected antibodies against six viruses as early as day 4 postinfection.

Infectious sinusitis in turkeys at Ibadan, Nigeria.

Thirty out of 70 imported broad-breasted white turkeys with severe sinusitis were both culturally and serologically positive for Mycoplasma gallisepticum. Infectious sinusitis due to M. gallisepticum was therefore diagnosed. A low mortality of 5.7% of the total flock was recorded. This appears to be the first published report on M. gallisepticum isolation in turkeys in Nigeria.