Biomedical subjects

M Brugh

Publications and source records attributed to M Brugh.

44 records · Page 3Linked to original sources

PubMedDate not supplied

A simple method for recording and analyzing serological data.

Titration endpoints from any 2-fold dilution series represent either true or modified base-2 logarithms and can be recorded conveniently by tube or dilution number. The simple arithmetic mean of titers thus expressed can be easily converted to geometric mean titer (GMT) by use of a table of antilogarithms, which is presented. This approach not only facilitates the handling of large volumes of data but also simplifies GMT calculation.

Animals↗

PubMedDate not supplied

Comparison of three experimental inactivated oil-emulsion Newcastle disease vaccines.

White Leghorn pullets vaccinated previously with live Newcastle disease virus (NDV) were revaccinated at point-of-lay with 3 experimental oil-emulsion (OE) Newcastle disease vaccines to determine whether immunogenicity of OE vaccines is influenced by emulsion composition differences. The vaccines used were formulated differently but contained equal amounts of inactivated NDV in stable, low-viscosity, water-in-oil emulsions. Serological responses to the vaccines differed (P less than 0.01), but 55 of 56 OE vaccinates remained clinically normal following challenge exposure with viscerotropic velogenic NDV 28 or 44 weeks after revaccination; 4 of 21 nonrevaccinated controls and all of 20 nonvaccinated challenge controls were clinically affected or died.

Animals↗

PubMedDate not supplied

Embryonated eggs compared with fragments of chorioallantois attached to egg shell for isolation of Newcastle disease virus.

The feasibility of using fragments of chorioallantois attached to egg shell (C-S) as an alternative to embryonated eggs for isolating Newcastle disease virus (NDV) was assessed. In paired titrations of 6 strains of virus, embryonated eggs detected an average of 6-to-7-fold greater amounts of virus than did C-S fragments. The efficiency of isolation of viscerotropic velogenic NDV from 240 swab samples was 97% in embryonated eggs and 84% in C-S fragments. Sensitivity differences between the 2 host systems were revealed only in tests of samples expected to contain small amounts of virus. These results suggest that C-S fragments can be reliably used in some but not all instances, thereby relieving logistic constraints sometimes associated with the use of embryonated eggs.

Allantois↗

PubMedDate not supplied

Assessment of the ability of ratite-origin influenza viruses to infect and produce disease in rheas and chickens.

Pathobiologic characteristics were determined for three mildly pathogenic (MP) ratite-origin avian influenza viruses (AIVs). Ratite-origin AIVs produced respiratory disease in rheas, and virus was reisolated from oropharyngeal and cloacal swabs on days 2-6 postinoculation. Inoculation of two ratite-origin AIVs in the upper respiratory tract of chickens resulted in viral infections, but the mean chicken infectious dose (CID50) for A/emu/Texas/39924/93 (H5N2) (Emu/Texas) virus was 500-fold lower than the CID50 for the A/rhea/North Carolina/39482/93 (H7N1) virus. In ovo and in vivo passage of the MP parent Emu/Texas isolate resulted in emergence of a highly pathogenic (HP) variant that had high plaquing efficiency in chicken embryo fibroblast cultures and was highly lethal in chicken pathotyping tests. This variant virus produced gross lesions in chickens similar to those reported for other HP AIVs. These findings demonstrated that ratite-origin AIVs can produce significant clinical disease in rheas and have a realistic potential for interspecies transmission to domestic poultry. Furthermore, HP variants can emerge from MP H5 ratite-origin AIVs if introduced and allowed to circulate in chicken populations.

Animals↗

PubMedDate not supplied

Pathogenicity of three avian influenza viruses for Leghorn hens of different ages.

Pronounced host effects on clinical responses to influenza virus infection were not observed in any of seven trials in which young (26-43 weeks) and olf (65-94 weeks) leghorn hens were inoculated with low pathogenic subtype H5N2, H4N8, or H3N2 virus. In two of seven trials, where hens were infected with H4N8 or H3N2 virus, morbidity rates were slightly higher for old hens than for young hens. These observations indicate that host age effects of the severity of uncomplicated influenza virus infections are likely to be minimal in sexually mature chickens.

Aging↗

PubMedDate not supplied

Comparative pathology of chickens experimentally inoculated with avian influenza viruses of low and high pathogenicity.

Pathologic changes and distribution of viral antigen as determined by immunohistochemistry were compared among 4-wk-old specific-pathogen-free chickens inoculated intratracheally with avian influenza virus (AIV) isolates of either low or high pathogenicity. Viruses of low pathogenicity, previously characterized as mildly pathogenic (MP), included A/chicken/Pennsylvania/21525/83 (H5N2) (MP-Penn) and A/chicken/Alabama/7395/75 (H4N8) (MP-Alab). Viruses of high pathogenicity included A/chicken/Pennsylvania/1370/83 (H5N2), A/chicken/Victoria/A185/85 (H7N7), and A/turkey/Ontario/7732/66 (H5N9). Extremely variable clinical signs ranging from mild respiratory distress to high mortality were present among chickens inoculated with these viruses. Chickens inoculated with highly pathogenic (HP) virus had histologic lesions of necrosis and inflammation in cloacal bursa, thymus, spleen, heart, pancreas, kidney, brain, trachea, lung, and skeletal muscle, whereas chickens inoculated with MP virus had histologic lesions most frequently in lung and trachea or lacked histologic lesions. Immunospecific staining for avian influenza viral proteins was most common in cells within heart, lung, kidney, brain, and pancreas of chicken inoculated with HP viruses, but immunospecific staining was present only and infrequently in trachea and lung of chickens inoculated with MP-Penn AIV. MP-Alab did not produce lesions nor have viral antigen in inoculated chickens but did produce serologic evidence of infection. The pattern of organ involvement and viral antigen distribution in chickens intratracheally inoculated with HP AIV isolates indicates a common capability to spread beyond the respiratory tract and confirms the pantrophic replicative, pathobiologic, and lethal nature of the viruses. However, variability in severity and lesion distribution exists between different HP AIVs. By contrast, MP viruses had the ability to replicate in respiratory or enteric tracts or both and produce lesions within the respiratory tract. These MP viruses exhibited a restricted ability to replicate or produce lesions or both in nonrespiratory or nonenteric tissues; such effects were associated with only sporadic deaths.

Animals↗

PubMedDate not supplied

Pathogenicity and diagnosis of H5N2 Mexican avian influenza viruses in chickens.

Chickens were inoculated with one of five H5N2 Mexican-origin avian influenza virus (AIV) isolates to determine their pathogenicity for chickens and to determine the ability of routine virologic and serologic tests to detect infections. In laboratory infections, three AIVs, H5/94, M5/94, and J12/94, produced sporadic illness and death and were categorized as mildly pathogenic. Q1/95 produced illness and death in all inoculated chickens and was categorized as highly lethal and highly pathogenic (HP). P11/94B commonly produced clinical illness, but deaths were infrequent. During the presence of clinical signs, oropharyngeal swabs were superior for isolation of AIV, but cloacal swabs were more successful after disappearance of clinical signs. Agar gel precipitin (AGP) serologic test was superior for detecting AIV infection during the clinical phase, but AGP and hemagglutinin inhibition tests were equally effective in detecting infections after recovery from clinical illness. Passage of P11/94B parent stock and selected 14-day-embryo-passed AIVs in adult hens resulted in emergence of some HP AIV derivatives. The hemagglutinin of Q1/95 and P11/ 94B parent stock and derivative AIVs had an identical proteolytic cleavage site of.... Pro-Gln-Arg-Lys-Arg-Lys-Thr-Arg-Gly, consistent with AIVs of high pathogenicity. However, no consistent differences were identified in the sequence of the hemagglutinin gene to explain the discrepancy in lethality patterns of the P11/94B AIVs. This suggests that genes other than the hemagglutinin impact the full expression of high lethality of Mexican-origin AIV infections in chickens.

Animals↗

PubMedDate not supplied

In ovo vaccination of chicken embryos with experimental Newcastle disease and avian influenza oil-emulsion vaccines.

Inactivated oil-emulsion (OE) Newcastle disease (ND) and avian influenza (AI) vaccines were injected into 18-day-old white rock (WR) and white leghorn (WL) chicken embryos to evaluate their immunologic efficacy and their effects on hatchability. Embryonating eggs were inoculated at 1.5 inches depth with various vaccine volumes and antigen concentrations. Serum hemagglutination-inhibition (HI) titers were first detected in chickens at 2 wk posthatch. Protection against morbidity and mortality was demonstrated in all of 10 chickens vaccinated as embryos and challenged with viscerotropic velogenic ND virus at 53 days of age and also in all of eight in ovo- vaccinated chickens challenged with highly pathogenic AI virus at 34 days of age. All of five unvaccinated control chickens for each respective ND- and AI-vaccinated group died. In pooled groups from successive hatches, the hatchability of WR or WL embryos injected with 100 microliters of vaccine was not significantly different (P > 0.05) from unvaccinated hatchmate controls when needle gauges of 22, 20, and 18 were used. Seroconversion rates of chickens vaccinated as embryos ranged from 27% to 100% with ND vaccination and 85% to 100% for AI vaccination. For ND, geometric mean HI titers of chickens per vaccine group ranged from 11 to 733, and in pooled groups, the range was 49 to 531. Titers for AI vaccine groups ranged from 156 to 1178. This study demonstrated that acceptable hatchability, seroconversion rates, and protective immunity can be attained with in ovo inoculation of ND or AI OE vaccines if the vaccines are prepared with sufficient antigen and administered properly.

Animals↗