Age and long-term protective immunity in dogs and cats.

Vaccination can provide an immune response that is similar in duration to that following a natural infection. In general, adaptive immunity to viruses develops earliest and is highly effective. Such anti-viral immune responses often result in the development of sterile immunity and the duration of immunity (DOI) is often lifelong. In contrast, adaptive immunity to bacteria, fungi or parasites develops more slowly and the DOI is generally short compared with most systemic viral infections. Sterile immunity to these infectious agents is less commonly engendered. Old dogs and cats rarely die from vaccine-preventable infectious disease, especially when they have been vaccinated and immunized as young adults (i.e. between 16 weeks and 1 year of age). However, young animals do die, often because vaccines were either not given or not given at an appropriate age (e.g. too early in life in the presence of maternally derived antibody [MDA]). More animals need to be vaccinated to increase herd (population) immunity. The present study examines the DOI for core viral vaccines in dogs that had not been revaccinated for as long as 9 years. These animals had serum antibody to canine distemper virus (CDV), canine parvovirus type 2 (CPV-2) and canine adenovirus type-1 (CAV-1) at levels considered protective and when challenged with these viruses, the dogs resisted infection and/or disease. Thus, even a single dose of modified live virus (MLV) canine core vaccines (against CDV, cav-2 and cpv-2) or MLV feline core vaccines (against feline parvovirus [FPV], feline calicivirus [FCV] and feline herpesvirus [FHV]), when administered at 16 weeks or older, could provide long-term immunity in a very high percentage of animals, while also increasing herd immunity.

Three-year duration of immunity in dogs vaccinated with a canarypox-vectored recombinant canine distemper virus vaccine.

Two studies evaluated the duration of serologic response to the recombinant, canarypox-vectored canine distemper virus vaccine (Recombitek, Merial). Serologic duration of immunity was shown to be at least 36 months. Thus, Recombitek provides protection when administered less frequently than the manufacturer's label. After the initial vaccination protocol of two or more doses administered approximately 4 weeks apart, with the last dose given at 12 to 16 weeks of age or older, and re-vaccination at 1 year of age, Recombitek can confidently be readministered every 3 years with assurance of protection in immunocompetent dogs. This allows the vaccine to be administered in accordance with the recommendations of the American Animal Hospital Association Canine Vaccine Task Force and others.

Three-year serologic immunity against canine parvovirus type 2 and canine adenovirus type 2 in dogs vaccinated with a canine combination vaccine.

A group of client-owned dogs and a group of dogs at a commercial kennel were evaluated for duration of antibody responses against canine parvovirus type 2 (CPV-2) and canine adenovirus type 1 (CAV-1) after receiving a combination vaccine containing recombinant canarypox-vectored canine distemper virus (CDV) and modified-live CPV-2, CAV-2, and canine parainfluenza virus, with (C6) or without (C4) two serovars of Leptospira (Recombitek C4 or C6, Merial). Duration of antibody, which correlates with protective immunity, was found to be at least 36 months in both groups. Recombitek combination vaccines can confidently be given every 3 years with assurance of protection in immunocompetent dogs against CPV-2 and CAV-1 as well as CDV. This allows this combination vaccine, like other, similar modified- live virus combination products containing CDV, CAV-2, and CPV-2, to be administered in accordance with the recommendations of the American Animal Hospital Association Canine Vaccine Task Force.

Effect of recombinant canine distemper vaccine on antibody titers in previously vaccinated dogs.

Two canine distemper virus (CDV) vaccine types are currently commercially available: modified-live virus (MLV) vaccines and a canarypox recombinant CDV (rCDV) vaccine (Recombitek, Merial). This study compared the ability of the rCDV vaccine and MLV vaccines to significantly enhance (boost) the antibody response of previously immunized adult and juvenile dogs. A significant (fourfold or greater) increase in titer occurred in significantly more dogs revaccinated with Recombitek C-4 or Recombitek C-6 than with the MLV-CDV vaccines. This study demonstrates that Recombitek, the only vaccine for dogs containing rCDV, is more likely to significantly boost the CDV antibody response in previously vaccinated dogs than are the MLV-CDV vaccines. Because rCDV vaccine can boost the antibody titer of dogs previously vaccinated with an MLV vaccine, it can and should be used when core vaccines are readministered.

Effect of vaccination with recombinant canine distemper virus vaccine immediately before exposure under shelter-like conditions.

Vaccination with modified-live virus (MLV) canine distemper virus (CDV) vaccine has historically been recommended for animals in high-risk environments because of the rapid onset of immunity following vaccination. Recombinant CDV (rCDV) vaccine was deemed a suitable alternative to MLV-CDV vaccination in pet dogs, but insufficient data precluded its use where CDV was a serious threat to puppies, such as in shelters, kennels, and pet stores. In this study, dogs experimentally challenged hours after a single dose of rCDV or MLV vaccine became sick but recovered, whereas unvaccinated dogs became sick and died. Dogs vaccinated with a single dose of rCDV or MLV vaccine 1 week before being experimentally challenged remained healthy and showed no clinical signs. Dogs given one dose of rCDV vaccine hours before being placed in a CDV-contaminated environment did not become sick. These findings support the hypothesis that rCDV vaccine has a similar time-to-immunity as MLV-CDV vaccines and can likewise protect dogs in high-risk environments after one dose.

Comparison of selected canine vaccines for their ability to induce protective immunity against canine parvovirus infection.

OBJECTIVE: To compare the ability of 6 commercially available multicomponent canine vaccines to stimulate antibody production in pups with variable amounts of maternally derived canine parvovirus (CPV) antibody and to induce protective immunity against challenge exposure. ANIMALS: Sixty-three 5- to 6-week-old Beagle pups with passively acquired CPV antibody titer between 1: 20 and 1:320. PROCEDURE: 9 pups were assigned to each of 6 vaccine groups and 1 control group. Eight pups in each group were inoculated with vaccine or saline solution twice, with 3 weeks between administrations. The ninth pup served as an uninoculated contact control. Serum samples were obtained weekly and tested for CPV antibody by hemagglutination-inhibition assay. All pups were challenge exposed with virulent CPV-2a and CPV-2b at 14 to 15 weeks of age. RESULTS: 3 of the vaccines failed to provide protective immunity against challenge exposure because all pups in these groups became infected and most died. A fourth vaccine protected against death, but not infection and disease. Two of the 6 vaccines induced an immune response that was protective against infection and disease. CONCLUSION AND CLINICAL RELEVANCE: Substantial differences existed among commercial vaccines available in 1994 in their ability to immunize pups with maternally derived CPV antibody. These differences caused many vaccinated pups to be susceptible to CPV disease for variable periods because some vaccines failed to immunize. Importantly, all 4 of the vaccines that performed poorly have recently been replaced by more effective products so that the 6 vaccines now perform similarly.

Hip instability in myelodysplasia.

Hip stability with reference to the ambulatory capacity of the myelodysplastic child is considered in a retrospective study. In 104 cases followed between 1950 and 1975, the patients were subdivided into 6 groups based on lowest functional neurological level as determined by hip motor power. Ninety-eight major operative procedures were performed about the hip in 50 patients. Over 50% of these operative procedures proved unsuccessful in stabilizing the involved hips. Mustard's transfer of the iliopsoas was used in a small group of patients and hip stability was attained in all cases. Sharrard's transfer was successful in only 2/3 of the cases. In all 6 groups, no difference in ambulatory capacity could be shown whether or not the patient had hip stability.

Identification and isolation of the major core protein from the oncornavirus-like particle in human milk.

Subviral cores have been prepared from the oncornavirus-like particle found in human milks with the use of phospholipase C and ether or Sterox SL. The major protein of these cores has a molecular weight of 27,000 daltons, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This protein is found in the core fractions of reverse transcriptase-positive milks and is absent in negative milks. It is distributed in sucrose gradients only in those fractions containing cores and reverse transcriptase activity. The major core protein of the human milk oncornavirus-like particle is electrophoretically identical to the major core protein of the mouse mammary tumor virus.