The number of mosquito-borne viruses (‘moboviruses’) occurring in Europe since the twentieth century now stands at ten; they belong to three families—Togaviridae (Sindbis, Chikungunya), Flaviviridae (West Nile, Usutu, Dengue), and Bunyaviridae (Batai, Ťahyňa, Snowshoe hare, Inkoo, Lednice). Several of them play a definite role in human or animal pathology (Sindbis, Chikungunya, Dengue, West Nile, Ťahyňa). Mobovirus outbreaks are strictly determined by the presence and/or import of particular competent vectors of the disease. Ecological variables affect moboviruses considerably; the main factors are population density of mosquito vectors and their vertebrate hosts, intense summer precipitations or floods, summer temperatures and drought, and presence of appropriate habitats, e.g., wetlands, small water pools, or intravillan sewage systems. A surveillance for moboviruses and the diseases they cause in Europe is recommendable, because the cases may often pass unnoticed or misdiagnosed not only in free-living vertebrates but also in domestic animals and even in humans.

Mosquito-borne viruses in Europe

Human bocavirus (HBoV), a newly cloned human virus of the genus Bocavirus, was detected by PCR from nasopharyngeal swab samples (8 of 318; 5.7%) collected from children with lower respiratory tract infections. HBoV may be one of the causative agents of lower respiratory tract infections in young children.

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Detection of Human Bocavirus in Japanese Children with Lower Respiratory Tract Infections

Canine parvovirus (CPV) is a host range variant of a feline virus that acquired the ability to infect dogs through changes in its capsid protein. Canine and feline viruses both use the feline transferrin receptor (TfR) to infect feline cells, and here we show that CPV infects canine cells through its ability to specifically bind the canine TfR. Receptor binding on host cells at 37°C only partially correlated with the host ranges of the viruses, and an intermediate virus strain (CPV type 2) bound to higher levels on cells than did either the feline panleukopenia virus or a later strain of CPV. During the process of adaptation to dogs the later variant strain of CPV gained the ability to more efficiently use the canine TfR for infection and also showed reduced binding to feline and canine cells compared to CPV type 2. Differences on the top and the side of the threefold spike of the capsid surface controlled specific TfR binding and the efficiency of binding to feline and canine cells, and these differences also determined the cell infection properties of the viruses.

The Natural Host Range Shift and Subsequent Evolution of Canine Parvovirus Resulted from Virus-Specific Binding to the Canine Transferrin Receptor

Some characteristics of a newly recognized porcine enteric virus are described. Tentatively, the virus was referred to as porcine pararotavirus (PaRV) because it resembled rotaviruses in respect to size, morphology, and tropism for villous enterocytes of the small intestine. However, it was antigenically distinct from porcine, human, and bovine rotaviruses and reoviruses 1, 2, and 3, and the electrophoretic migration pattern of PaRV double-stranded RNA was distinct from the electrophoretic migration patterns of the rotaviral and reoviral genomes. By passage in gnotobiotic pigs, PaRV was isolated from two suckling diarrheic pigs originating from two herds. After oral exposure of gnotobiotic pigs, villous enterocytes of the small intestines became infected as judged by immunofluorescence, resulting in villous atrophy and diarrhea. Mortality was high when gnotobiotic pigs less than 5 days old were infected. The C strain of this virus was serially passed 10 times in gnotobiotic pigs, and electron microscopy, immunofluorescence, and serological tests indicated no extraneous agents. The virus was serially passed five times in cell cultures which contained pancreatin in the medium, but replication was negligible or absent, as the number of immunofluorescent cells decreased with each passage. Since rotaviral infections are frequently diagnosed by direct electron microscopy of fecal specimens, the presence of other morphologically similar viruses, such as PaRV, should be considered. The use of immune electron microscopy is suggested as a means of helping recognize this situation.

https://jcm.asm.org/content/jcm/15/2/312.full.pdf

Porcine pararotavirus: detection, differentiation from rotavirus, and pathogenesis in gnotobiotic pigs.

Background A new human-pathogenic parvovirus, human bocavirus (HBoV), has recently been discovered and associated with respiratory disease in small children. However, many patients have presented with low viral DNA loads, suggesting HBoV persistence and rendering polymerase chain reaction-based diagnosis problematic. Moreover, nothing is known of HBoV immunity. We examined HBoV-specific systemic B cell responses and assessed their diagnostic use in young children with respiratory disease. Patients and methods Paired serum samples from 117 children with acute wheezing, previously studied for 16 respiratory viruses, were tested by immunoblot assays using 2 recombinant HBoV capsid antigens: the unique part of virus protein 1 and virus protein 2. Results Virus protein 2 was superior to the unique part of virus protein 1 with respect to immunoreactivity. According to the virus protein 2 assay, 24 (49%) of 49 children who were positive for HBoV according to polymerase chain reaction had immunoglobulin (Ig) M antibodies, 36 (73%) had IgG antibodies, and 29 (59%) exhibited IgM antibodies and/or an increase in IgG antibody level. Of 22 patients with an increase in antibody levels, 20 (91%) had a high load of HBoV DNA in the nasopharynx, supporting the hypothesis that a high HBoV DNA load indicates acute primary infection, whereas a low load seems to be of less clinical significance. In a subgroup of patients who were previously determined to have acute HBoV infection (defined as a high virus load in the nasopharynx, viremia, and absence of other viral infections), 9 (100%) of 9 patients had serological evidence of primary infection. In the control group of 68 children with wheezing who had polymerase chain reaction results negative for HBoV in the nasopharynx, 9 (13%) had IgM antibodies, including 5 who displayed an increase in IgG antibody levels and were viremic. No cross-reactivity with human parvovirus B19 was detected. Conclusions Respiratory infections due to HBoV are systemic, elicit B cell immune responses, and can be diagnosed serologically. Serological diagnoses correlate with high virus loads in the nasopharynx and with viremia. Serological testing is an accurate tool for disclosing the association of HBoV infection with disease.

/pdf/serodiagnosis-of-human-bocavirus-infection-4j654195xx.pdf

Serodiagnosis of Human Bocavirus Infection

Thirteen cases of a previously undescribed parvoviral infection affecting puppies ranging in age from 5 to 21 days is described. The cases were originally thought to represent an unusual pathologic manifestation of canine parvovirus-2 (CPV-2) infection. However, failure to confirm CPV-2 infection in any of the cases suggested a different parvovirus was involved. Minute virus of canines (MVC) was subsequently isolated from a case by using the Walter Reed Canine Cell Line, the only cell line which will support the growth of MVC. The pathologic and virologic findings for these 13 cases are described in this report.

https://journals.sagepub.com/doi/pdf/10.1177/104063879200400105

Fatal Disease in Nursing Puppies Associated with Minute Virus of Canines

Acetone fixation and fluorescent-antibody staining of virus-infected cell cultures were performed in plastic plates. Proper addition of acetone as a fixative did not alter the plastic.

Procedure for Fluorescent-Antibody Staining of Virus-Infected Cell Cultures in Plastic Plates

Arboviral encephalitis in domestic animals in the United States is rare with the exception of equine encephalomyelitis in horses This report describes 2 cases in which La Crosse virus (LACV) was isolated from canine littermates with acute clinical encephalitis or sudden death Both cases occurred in the southern region of the state of Georgia and were submitted as cadavers for necropsy to the Veterinary Diagnostic and Investigational Laboratory (VDIL) in Tifton, Georgia On May 9, 1988, 4 2-week-old mixed-breed littermate puppies exhibited acute signs of central nervous system disease and were taken to a veterinarian Three of the puppies had repeated seizures during the clinical examination Because the clinical signs were compatible with a diagnosis of canine distemper virus encephalitis, the veterinarian issued a poor prognosis; the 3 puppies were euthanized and submitted to the VDIL for necropsy The fourth puppy was mildly affected and was sent home without follow-up On May 28, 1991, illness and deaths occurred in a litter of 7 8-day-old Brittany spaniel puppies Two puppies were found dead and were taken to a veterinarian, who submitted the cadavers to the VDIL for necropsy A third puppy was moribund and experienced breathing difficulty and died within the following hour The veterinarian examined the 4 remaining puppies later that day and found them to be healthy The same veterinarian had examined the entire litter 5 days previously At that time, the animals appeared healthy, and tail docking was performed A necropsy was performed on each of the 3 mixed-breed and 2 Brittany spaniel puppies submitted to the VDIL Macroscopically, the brain of each puppy was severely and diffusely malacic Other tissues appeared normal Representative sections of lung, heart, liver, kidney, urinary bladder,

/pdf/necrotizing-panencephalitis-in-puppies-infected-with-la-50ti6ouyye.pdf

Alfred R. Pursell

Papers

Fatal Disease in Nursing Puppies Associated with Minute Virus of Canines

Procedure for Fluorescent-Antibody Staining of Virus-Infected Cell Cultures in Plastic Plates

Necrotizing panencephalitis in puppies infected with La Crosse virus

Antibody titers to pseudorabies virus in piglets immunized with gIII deleted pseudorabies vaccine in a pseudorabies infected herd.