Discrepancy Between In-clinic and Haemagglutination-Inhibition Tests in Detecting Maternally-Derived Antibodies Against Canine Parvovirus in Puppies

Molecular epidemiology of canine parvovirus type 2 in Sicily, southern Italy: A geographical island, an epidemiological continuum

Since it emerged as a major dog pathogen, canine parvovirus type 2 (CPV-2) has featured a remarkable genetic and phenotypic heterogeneity, whose biological, epidemiological, and clinical impact is still debated. The continuous monitoring of this pathogen is thus of pivotal importance. In the present study, the molecular epidemiology of CPV-2 in Sicily, southern Italy, has been updated by analysing 215 nearly complete sequences of the capsid protein VP2, obtained from rectal swabs/faeces or tissue samples collected between 2019 and 2022 from 346 dogs with suspected infectious gastrointestinal disease. The presence of the original CPV-2 type (4%) and CPV-2a (9%), CPV-2b (18%), or CPV-2c (69%) variants was documented. Over the years, we observed a decrease in the frequency of CPV-2a/-2b and a rapid increase of CPV-2c frequency, with a progressive replacement of the European lineage of CPV-2c by the Asian lineage. The observed scenario, besides confirming epidemiological relevance of CPV-2, highlights the occurrence of antigenic variant shifts over time, with a trend toward the replacement of CPV-2a, CPV-2b, and the European lineage of CPV-2c by the emerging Asian CPV-2c lineage. The comparison with other Italian and international sequences suggests the occurrence of viral exchange with other Italian regions and different countries, although the directionality of such viral flows could not be often established with confidence. In several instances, potential CPV-2 introductions led to epidemiological dead ends. However, major, long-lasting clades were also identified, supporting successful infection establishment, local spreading, and evolution. These results, besides demonstrating the need for implementing more effective control measures to prevent viral introductions and minimize circulation, stress the relevance of routine monitoring activities as the only tool to effectively understand CPV-2 epidemiology and evolution, and develop adequate countermeasures.

A novel lateral flow immunochromatographic assay using a recombinant VP2 antigen for total antibody detection of canine parvovirus-2

Canine parvovirus-2 (CPV-2) is a viral disease of dogs causing acute hemorrhagic gastroenteritis and myocarditis with high morbidity and mortality rates. The infection is still widespread all over the world. Vaccines developed against infection have great importance in preventing infection. However, it is difficult to recommend a practical vaccination program without knowing the antibody level of a puppy. Despite widespread vaccination, difficulties in detecting the maternal antibodies in puppies remain the main cause of vaccination failure. The hemagglutination inhibition (HAI) test is the gold standard to determine the immune status of dogs for canine parvovirus 2, but the HAI test has several disadvantages such as the need for fresh porcine blood, well-equipped laboratory, and long incubation periods. In this study, for the first time we developed a colloidal gold-based competitive lateral flow assay (cLFA) system for the rapid detection of total antibodies in canine serum using CPV-2b-VP2 derived from field isolates. The recombinantly expressed capsid protein of CPV-2 in the prokaryotic expression system was used as a labeled molecule in cLFA. We carried out studies on our cLFA system using the standard antibody solution and the clinical samples from vaccinated puppy serum. We compared the results of the LFAs with the HAI test. Competitive lateral flow assay results showed good correlation with the gold standard method, the HAI test. In the developed platform, the limit of detection of the standard antibody was determined to be 375 ng mL-1, while the cut-off level of antibodies was observed to be 1 : 40 HAI titer in clinical samples. Our reported system will be a strong alternative for CPV-2 antibody-based detection applications.

Prevalence of Serum Antibody Titers against Core Vaccine Antigens in Italian Cats

Feline core vaccines strongly recommended for all cats are against Feline panleukopenia virus (FPV), Felid herpesvirus type 1 (FeHV-1), and Feline calicivirus (FCV), but cats can be classified as low- and high-risk based on their lifestyle. The aim of this study was to determine the actual seroprotection against FPV, FeHV-1, and FCV in a large cohort of Italian cats by using the VacciCheck test. A total of 740 cats (567 owned and 173 stray cats; 435 vaccinated and 305 unvaccinated) were analyzed for Protective Antibody Titers (PATs). Differences related to origin, sex, age, breed, FIV/FeLV status, health status, and time elapsed since last vaccination were evaluated. Less than half of the entire cohort (36.4%) had PATs for all three diseases simultaneously, increasing to 48.6% if weak positive values were also considered and 50.3% when considering only the 435 vaccinated cats. Particularly, antibodies were detected against FCV, FPV, and FeHV-1 at protective titers (PATs) in 78.6%, 68.1, and 49.1% of the cats, respectively. In general, owned, neutered, and adult FIV- and/or FeLV-negative cats were the most protected categories, even if not always for the three viruses. Most cats maintained high PATs for 3 years or longer after vaccination against FPV and FCV but not FeHV-1. Long-lasting protective immunity persisted for many years after the last vaccination (more than 18 years in the oldest cats). Nevertheless, since not all cats were protected after so many years and for all pathogens, checking protection via antibody titration could be the best choice to prevent immunity breakdowns. The discussion also focuses on the reliability of antibody titration for the two URTD (upper respiratory tract disease) viruses which, unlike for FPV, is not widely accepted as a valid index of protection.

Effect of Aging on the Immune Response to Core Vaccines in Senior and Geriatric Dogs

Elderly dogs are steadily increasing worldwide as well as veterinarians' and owners' interest in their health and wellness. Aging is not a disease, but a combination of changes negatively affecting the organism in general and the immune system in particular, resulting in a decline in protection over time. The aim of this study was to measure the specific serum antibody titers against the main dangerous and widespread viral diseases preventable by core vaccinations in senior and geriatric dogs using the in-practice test VacciCheck. A cohort of three hundred fifty elderly dogs was analyzed for Protective Antibody Titers (PATs) against CPV-2, CDV and CAdV-1. The age ranged from 5 to 19 years, with two hundred fifty-eight seniors (73.7%) and ninety-two geriatrics (26.3%), and 97.4% of them were vaccinated at least once in their lives. More than half of the entire study population (52.9%) had PATs simultaneously for all three diseases, with 80.5% seniors and 19.5% geriatrics. Specific PATs were found in 88.6% of aging dogs for CPV-2, 82.3% for CadV-1 and 66.0% for CDV, demonstrating that unprotected aging dogs represent a minority. Unexpectedly, the larger elderly dogs resulted as more protected than smaller ones for CPV-2. Protection then decreases over time, with geriatric dogs less protected than senior ones. Veterinary practitioners should therefore always consider whether to maintain core vaccinations in aging dogs as in adults on a three-year basis or opt instead for closer boosters (every 1 or 2 years). PATs for core vaccines could then represent a good biomarker of protection and their titration could become a standard of care, especially in such a sensitive period of the dogs' life.

Prevalence of Serum Antibody Titers against Core Vaccine Antigens in Italian Dogs

Canine vaccination is the main tool for preventing dangerous and widespread diseases. The strongly recommended (core) dog vaccines are against Canine Parvovirus type 2 (CPV-2), Canine Distemper Virus (CDV), and Canine Adenovirus (CAdV-1), but vaccination protocols should be tailored to dog lifestyles. Vaccination guidelines suggest vaccinating adult dogs no more frequently than every 3 years using modified live (attenuated) vaccines (MLV), thus obtaining a long-lasting (sometimes throughout life) specific protection in many but not all animals. The aim of this study was to determine the actual levels of seroprotection against CPV-2, CDV and CAdV-1 in a cohort of Italian dogs by using the in-practice test VacciCheck. A total of 1,027 dogs (951 vaccinated and 76 unvaccinated) were analyzed for Protective Antibody Titers (PATs) against CPV-2, CDV, and CAdV-1. Differences related to sex, age, breed size, health status, and time elapsed since last vaccination were evaluated. Half of the entire canine cohort (50.6%) had PATs for all three viruses (68.5% considering only vaccinated dogs). In particular, 90.8% of dogs were protected against CPV-2, 68.6% against CDV, and 79.8% against CAdV-1. Most dogs remained protected for 3 years after vaccination or longer. Revaccination on a 3-year basis can then be recommended for core MLV vaccines without altering individual's seroprotection or even herd immunity.

The first evaluation of the effectiveness of canine vaccination schedule by two commercial vaccines in Iran

Background

Canine Parvovirus type 2 (CPV-2) is a member of the Parvoviridae family with a global distribution and causes pathogenicity in puppies aged from 6 weeks to 6 months. It should be noted that Maternally Derived Antibodies (MDA) have protection against CPV-2 in the first weeks of puppies’ life. However, MDA declines with age. The most important influential factor is timely vaccination against CPV-2.

Methods

In this study, 24 healthy 8-week-old terrier puppies were selected and divided into three identical groups based on a randomized, double-blind comparative trial. One of which was called the control group that was injected with the physiological serum. The second group was the group A that was vaccinated by the vaccine provided by Biocan DHPPi+L (Bioveta, Czech). The third group was group B that was vaccinated by the vaccine of Duramune Max 5 + LCI / GP (Fort Dodge Animal Health, USA) from 8 to 16 weeks of their life at every 4 weeks. Then serum samples were analyzed with HI and ELISA tests.

Results

The MDA titer was protective in some puppies until 18 weeks of age. Also, after the first vaccination, all puppies had a protective titer against CPV-2, and Duramune vaccine had seroconverted after the first injection and Biocan had seroconverted after the second injection.

Conclusions

It is recommended that to reduce the risk of vaccine failure: such as the MDA titer should be measured in puppies before designing a vaccination schedule.