Effect of multiple cell culture passages on the biological behaviour of chicken anaemia virus

Abstract

The Cux-1 isolate of chicken anaemia virus (CAV) was passaged over 320 times in Marek's disease virus transformed chicken lymphoblastoid (MDCC-MSB1) cells. Comparison of the infectivity titres of virus pools derived from viruses that had received 0 (P0), 49 (P49), 170 (P170) and 320 (P320) passages in our laboratory indicated that the yields of infectious virus increased over 100-fold with passage number from P0 to P170. P320 exhibited unusual cell culture growth characteristics in that, unlike its lower passage counterparts, virus-specific immunofluorescence (IF) and cytopathic effect were detected at very low levels at 2 days post infection, with an additional passage of infected cells into fresh medium being required to produce high levels of infectious virus. Experimental infection of 1-day-old SPF chicks showed that P170 and P320 were substantially attenuated compared to P49 and a pathogenic, low-passage isolate used as control. When assessed by the indirect IF test, infection of 1-day-old chicks with the P49 and P170 isolates elicited similar levels of CAV-specific antibody to those elicited by infection with the pathogenic, low-passage virus and higher than those elicited by infection with the P320 isolate. Experimental infection of 5-week-old chicks indicated that the attenuated P170 and P320 isolates invoked similar CAV-specific antibody levels to those invoked by the pathogenic P49 and control isolates.

Comparative immunological studies on some single and combined live attenuated vaccines in poultry

“…On the other hand, live attenuated CAV vaccine is safe if inoculated simultaneously with FP vaccine and not cause immunosuppression (Hanan et al, 2008). Also, CAV vaccine not reverse to its virulence as mentioned by Todd et al, (1995Todd et al, ( , 1998.so, it could be concluded that FP virus strain not has antagonistic reaction with AE, Reo or CA virus strains. Moreover, FP virus stimulates the Weeks post vaccination ELISA antibody titre GMT in chicken group Group (2) Group (3) Group (8) Weeks post vaccination ELISA antibody GMT of chicken group Group (6) Group (7) Group (8) (2) Group (3) Group ( Weeks Post Vaccination ELISA antibody GMT Group (6) Group (7) Group (8) (5): Chickens simultaneously vaccinated with live attenuated Reo vaccine and FP vaccine which used in subgroup 1B.…”

Investigation of the unstable attenuation exhibited by a chicken anaemia virus isolate

“…Unstable CAV attenuation 379 19.42 (9/7.38) 6)/1'/, 5)/2'/ 4)/1'/, 1)/2'/ 1.83 (0 Á/4) 2 Cloned isolate 10 6.0 11 2 31.36 (9/4.15) 2)/1'/ 1)/1'/ 0.27 (0 Á/1) 2 Cloned Rev 18 6.25 12 0 30.33 (9/1.72) 0 0 0.00 (0 Á/0) a One-day-old SPF chicks were inoculated intramuscularly and assessed at 14 days post-inoculation for anaemia and gross lesions of thymus and bone marrow. b The clinical score was estimated by taking the numbers of birds showing lesions of the bone marrow and thymus, and the severity of lesion (1'/ or 2'/) into consideration, as described by Todd et al . (1998).…”

“…The results indicated that all five isolates were substantially attenuated in comparison with the pool of low passage Cux CAV used as the pathogenic control. This was evident from a comparison of the proportions of birds showing anaemia (haematocrit values of less than 27%), the mean haematocrit values and the clinical scores, which were estimated from the extent and severity of gross lesions in the bone marrow and thymus, as previously described (Todd et al, 1998). With cloned Rev isolates 13 and 18, the levels of attenuation were similar to, or greater than, that of cloned isolate 10.…”

“…Experimental infections of 1-day-old SPF chicks were performed to evaluate the pathogenicities of cloned Rev isolates using the disease model established previously in our laboratory (Todd et al ., 1998).…”

“…A long-term goal of our research is to produce attenuated isolates for evaluation as live vaccines to protect against the clinical and subclinical diseases induced by CAV. Our approach is based on the finding that the pathogenicity of the Cuxhaven-1 (Cux) isolate of CAV is markedly reduced following multiple passages in a Marek's disease virus-transformed chicken lymphoblastoid (MDCC-MSB1) cell line (Todd et al, 1998). Recombinant DNA cloning of the CAV RF molecules and transfection methods have been used to select individual 'cloned virus isolates' from the genetically diverse, highly-passaged virus pools (Todd et al, 1995).…”